JP6785964B2 - Solar cells and solar modules - Google Patents

Description

The present invention relates to a solar cell that constitutes a solar cell module by being connected by a lead wire, and a solar cell module that uses the solar cell.

When modularizing solar cells, a lead wire made of flat copper wire is soldered to each solar cell for the purpose of electrically connecting multiple solar cells in series to extract electrical output. Ru. The lead wire usually shrinks when cooled from a high temperature state immediately after soldering to room temperature. Then, the solar cell after the soldering of the lead wire is warped due to the shrinkage of the lead wire. This warp of the solar cell causes damage to the solar cell.

A grid electrode for extracting electricity generated in the solar cell and a bus electrode for collecting electricity from all the grid electrodes are arranged on the light receiving surface and the back surface of the solar cell. Grid electrodes are becoming thinner and more numerous in order to improve the power generation area of solar cells. On the other hand, it is difficult to thin the bus electrode because of the relationship between ensuring the adhesive strength between the solar cell and the lead wire and the placement accuracy. Furthermore, the heat treatment during the formation of the grid electrode and the bus electrode causes damage to the power generation layer and reduces the power generation efficiency of the solar cell, so the area is reduced as much as possible in combination with the use of expensive silver as the electrode material. There is a need.

In Patent Document 1, the electrode paste is screen-printed so that the bus bar portion formed on the main surface of the semiconductor substrate partially has slit portions in which a plurality of slits are arranged along the longitudinal direction of the bus bar portion. Printing by law is disclosed. According to the technique of Patent Document 1, the area of the bus bar electrode can be reduced while maintaining good adhesive strength between the bus bar electrode and the lead wire, but the warp of the solar cell generated after joining the lead wires can be reduced. It has not been resolved.

On the other hand, the back surface of the solar cell requires a bus electrode for joining with the back surface lead wire as well as the light receiving surface, but the linearly arranged bus electrode requires a large amount of electrode material. It is being considered to arrange an island-shaped junction electrode instead of a linear shape.

Japanese Patent No. 4284368

However, in recent years, the thickness of the silicon substrate used for solar cells has been decreasing year by year, and it is considered that the thickness will continue to decrease in the future. In the manufacturing process of the solar cell module, warpage occurs due to the difference in the coefficient of thermal expansion between the lead wire and the solar cell, so it is necessary to reduce the warpage in the module manufacturing process. The occurrence of this warp becomes more remarkable as the thickness of the silicon substrate becomes thinner.

The present invention has been made in view of the above, and an object of the present invention is to obtain a solar cell capable of suppressing warpage of the solar cell due to joining of a lead wire to the solar cell.

In order to solve the above-mentioned problems and achieve the object, the present invention comprises a semiconductor substrate having a pn junction and a light receiving surface bus electrode extending in the first direction on the light receiving surface side of the semiconductor substrate. , A light receiving surface electrode having a plurality of light receiving surface grid electrodes provided parallel to the second direction intersecting the light receiving surface bus electrode and connected to the light receiving surface bus electrode, and facing the side opposite to the light receiving surface in the semiconductor substrate. A plurality of back surface connecting electrodes distributed and arranged along the first direction on the back surface side, and a back surface current collector provided on the entire region other than the back surface connecting electrode on the back surface and connected to the plurality of back surface connecting electrodes. A back electrode having an electrode and a back electrode having the same . The light receiving surface bus electrode is provided with a plurality of through holes penetrating in the thickness direction of the light receiving surface bus electrode along the first direction, and the back surface connection electrode is a region excluding the plurality of through holes in the light receiving surface bus electrode. They are arranged at opposite positions in the thickness direction of the semiconductor substrate. The light receiving surface bus electrode includes a plurality of first regions in which the through holes are not provided in the first direction, and a plurality of second regions in which the through holes are provided in the first direction. The back surface connection electrodes are arranged at positions facing each other in the thickness direction of the semiconductor substrate with the plurality of first regions. In the first direction, the first region of the light receiving surface bus electrode is longer than the back surface connecting electrodes arranged at opposite positions in the thickness direction of the semiconductor substrate. In the first direction, the sum of the lengths of the plurality of first regions of the light receiving surface bus electrodes is longer than the sum of the lengths of the plurality of back surface connecting electrodes. The light receiving surface electrode and the back surface connecting electrode are paste electrodes containing silver and glass. The light receiving surface electrode has a higher ratio of silver in the electrode material than the back surface connecting electrode. The back surface connection electrode has a higher ratio of glass in the electrode material than the light receiving surface electrode.

The solar cell according to the present invention has an effect that the warp of the solar cell due to the joining of the lead wire to the solar cell can be suppressed.

Perspective view of the solar cell module according to the first embodiment of the present invention as viewed from the light receiving surface side. An exploded perspective view of the solar cell module according to the first embodiment of the present invention as viewed from the light receiving surface side. Sectional sectional view of the main part of the solar cell module according to Embodiment 1 of this invention Perspective view of the solar cell array according to the first embodiment of the present invention as viewed from the back surface side. Perspective view of the solar cell string according to the first embodiment of the present invention as viewed from the light receiving surface side. Perspective view of the solar cell string according to the first embodiment of the present invention as viewed from the back surface side. Top view of the solar cell according to the first embodiment of the present invention as viewed from the light receiving surface side. Top view of the solar cell according to the first embodiment of the present invention as viewed from the back surface side facing the side opposite to the light receiving surface side. It is sectional drawing which shows the structure of the solar cell which concerns on Embodiment 1 of this invention, and is the sectional view of the main part in IX-IX line in FIG. It is sectional drawing which shows the structure of the solar cell which concerns on Embodiment 1 of this invention, and is the sectional view of the main part by X-ray in FIG. Top view showing the shape of the light receiving surface bus electrode of the solar cell according to the first embodiment of the present invention. A plan view showing a state in which a lead wire is soldered onto a bus electrode on the light receiving surface of the solar cell according to the first embodiment of the present invention. It is sectional drawing which shows the structure of the solar cell which concerns on Embodiment 1 of this invention, and is the sectional view of the main part in line XIII-XIII in FIG. It is sectional drawing which shows the structure of the solar cell which concerns on Embodiment 1 of this invention, and is the sectional view of the main part in line XIV-XIV in FIG. A flowchart illustrating a procedure of a solar cell manufacturing process according to the first embodiment of the present invention. Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention Sectional drawing of the main part which shows the manufacturing process of the solar cell which concerns on Embodiment 1 of this invention A flowchart showing a procedure of a method for manufacturing a solar cell module according to a first embodiment of the present invention. Top view of the solar cell according to the second embodiment of the present invention as viewed from the light receiving surface side. Top view of the solar cell according to the second embodiment of the present invention as viewed from the back surface side facing the side opposite to the light receiving surface side. Sectional drawing of the main part which shows the structure of the solar cell module which concerns on Embodiment 2 of this invention. The figure which shows the constitutional condition of the light receiving surface electrode of the solar cell which concerns on Embodiment 2 of this invention. The figure which shows the constituent condition of the back surface connection electrode of the solar cell which concerns on Embodiment 2 of this invention. Sectional drawing which shows the structure of the solar cell which concerns on Embodiment 3 of this invention. The figure which shows the constitutional condition of the light receiving surface electrode of the solar cell which concerns on Embodiment 3 of this invention. The figure which shows the constituent condition of the back surface connection electrode of the solar cell which concerns on Embodiment 3 of this invention.

Hereinafter, the solar cell and the solar cell module according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a 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. 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 a main part of the solar cell module 100 according to the first embodiment of the present invention. 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 material 33 and the light receiving surface protection portion 31, and the solar cell 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 portion 32, and the outer peripheral edge portion is surrounded by the reinforcing frame 40.

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 surface side. FIG. 5 is a perspective view 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 the solar cell string 50 according to the first embodiment of the present invention as viewed from the back surface side.

As shown in FIG. 4, the solar cell array 70 is composed of a plurality of solar cell strings 50 electrically and mechanically joined in series or in parallel by horizontal lead wires 25 and output lead wires 26.

Further, as shown in FIGS. 3 to 6, in the solar cell string 50, a plurality of solar cells 10 having a square shape arranged adjacent to each other are electrically and mechanically connected to each other in series by a lead wire 20. It is composed of. As shown in FIGS. 3 to 6, the plurality of solar cell 10s are connected in series by the lead wire 20 in the X direction in the drawing, which is the first direction. The first direction is the connecting direction of the plurality of solar cells 10 connected by the lead wire 20.

In the solar cell string 50, the electrode formed on the light receiving surface side which is the first main surface of one of the two adjacent solar cells 10 and the two adjacent solar cells 10 Electrodes formed on the back surface side, which is the second main surface of the other solar cell 10, are alternately connected by lead wires 20. One end of the lead wire 20 is solder-bonded to the back surface connection electrode 13B formed on the back surface side of the solar cell 10 described later, and the light receiving surface bus electrode 12B formed on the light receiving surface side of the adjacent solar cell 10 is formed. The other end is solder-bonded to. That is, the lead wire 20 connected to the light receiving surface bus electrode 12B formed on the light receiving surface side of the solar cell 10 is connected to the back surface connecting electrode 13B formed on the back surface side of the adjacent solar cell 10. , A plurality of solar cell 10s are connected in series.

FIG. 7 is a plan view of the solar 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 cell 10 according to the first embodiment of the present invention as viewed from the back surface side facing the side opposite to the light receiving surface side. FIG. 9 is a cross-sectional view showing the configuration of the solar cell 10 according to the first embodiment of the present invention, and is a cross-sectional view of a main part of the IX-IX line in FIG. FIG. 10 is a cross-sectional view showing the configuration of the solar cell 10 according to the first embodiment of the present invention, and is a cross-sectional view of a main part in line XX of FIG. In addition, in FIG. 9 and FIG. 10, the lead wire 20 connected to the solar cell 10 is also shown.

The solar cell 10 includes a semiconductor substrate 11 having a quadrangular shape in which an impurity diffusion layer is formed and a pn junction is formed. That is, in the solar cell 10, n is an impurity diffusion layer in which n-type impurities are diffused by phosphorus diffusion on the light receiving surface side which is the surface of the semiconductor substrate 1 made of p-type silicon which is the first conductive type. The type impurity diffusion layer 2 is formed. The n-type impurity diffusion layer 2 is formed on the light receiving surface 11A side of the semiconductor substrate 11. The outer shape of the semiconductor substrate 11 has a square shape, that is, a rectangular shape in the plane direction of the semiconductor substrate 11.

The solar cell 10 has an uneven shape formed on the light receiving surface 11A side of the semiconductor substrate, which is the first main surface of the semiconductor substrate 11, by texture etching in order to increase the light condensing rate. That is, minute irregularities are formed on the surface of the semiconductor substrate 11 as a texture structure. The micro-concavities and convexities increase the area of the light receiving surface 11A that absorbs light from the outside, suppress the reflectance of the light receiving surface 11A, and confine the light. In addition, in FIG. 9 and FIG. 10, the illustration of minute unevenness is omitted for convenience. Further, in the solar cell 10, an antireflection film 3 made of a silicon nitride film is formed on the light receiving surface 11A side of the semiconductor substrate, which is the first main surface of the semiconductor substrate 11.

As the semiconductor substrate 1, a p-type single crystal silicon substrate or a p-type polycrystalline silicon substrate can be used. The semiconductor substrate 1 is not limited to this, and an n-type single crystal silicon substrate, an n-type polycrystalline silicon substrate, or another silicon-based substrate may be used. Further, a silicon oxide film may be used as the antireflection film 3.

Further, in the solar cell 10, a light receiving surface electrode 12 is formed on the light receiving surface 11A side of the semiconductor substrate, and a 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.

The light-receiving surface electrode 12 described above is provided on the light-receiving surface side of the semiconductor substrate 1 by penetrating the antireflection film 3 and electrically connecting to the n-type impurity diffusion layer 2. As the light receiving surface electrode 12, a plurality of long and slender light receiving surface grid electrodes 12G are provided side by side in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11. The light receiving surface grid electrode 12G is an electrode for collecting the photocurrent generated by the solar cell 10 from the light receiving surface 11A side of the semiconductor substrate 11. The light receiving surface grid electrode 12G is electrically connected to the n-type impurity diffusion layer 2 at the bottom surface. The light receiving surface grid electrode 12G is a paste electrode formed by applying a conductive paste having metal particles to a desired range and firing.

Further, the light receiving surface bus electrode 12B conducting with the light receiving surface grid electrode 12G is provided orthogonal to the light receiving surface grid electrode 12G in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11. As shown in FIG. 7, the light receiving surface bus electrodes 12B are provided in four rows in a line over substantially the entire length of the solar cell 10 along the first direction which is the connecting direction of the solar cell 10. .. That is, the longitudinal direction of the light receiving surface bus electrode 12B is the same direction as the first direction described above, and is the connecting direction of the plurality of solar cells 10 connected by the lead wires 20. Further, the arrangement direction of the light receiving surface bus electrodes 12B is the same as the second direction orthogonal to the first direction in the plane of the semiconductor substrate 11. The light receiving surface bus electrode 12B is provided in connection with all the light receiving surface grid electrodes 12G. The light receiving surface bus electrode 12B is electrically connected to the n-type impurity diffusion layer 2 at the bottom surface. For convenience, FIGS. 1, 2, 4 and 5 show a case where the light receiving surface bus electrodes 12B are provided in two rows.

The light receiving surface bus electrode 12B is an electrode provided for collecting the photocurrent collected in the light receiving surface grid electrode 12G and for electrically joining the lead wire 20. The light receiving surface bath electrode 12B is a paste electrode formed by applying a conductive paste having metal particles to a desired range and firing it. A lead wire 20 is soldered to the light receiving surface bus electrode 12B as shown in FIGS. 9 and 10 when the solar cell module 100 is manufactured by using the solar cell 10. Note that, in FIGS. 9 and 10, only the light receiving surface bus electrode 12B of the light receiving surface electrodes 12 is shown.

FIG. 11 is a plan view showing the shape of the light receiving surface bus electrode 12B of the solar cell 10 according to the first embodiment of the present invention. As shown in FIGS. 7 and 11, a plurality of through holes 60 penetrating the light receiving surface bus electrode 12B in the thickness direction are formed inside the light receiving surface bus electrode 12B in the in-plane direction of the solar cell 10, that is, the semiconductor substrate. It is provided in a stepping stone shape along the first direction in the in-plane direction of 11. In FIG. 7, as an example, a case where seven through holes 60 are provided in the light receiving surface bus electrode 12B along the first direction is shown.

That is, the light receiving surface bus electrode 12B includes a plurality of first regions 61 in which the through holes 60 are not provided, and a plurality of second regions 62 in which the through holes 60 are provided, in the first direction. The plurality of first regions 61 and the plurality of second regions 62 are alternately provided in the extension direction of the light receiving surface bus electrode 12B, that is, in the first direction. In the second region 62, the connecting portions 63 provided in the outer edge region of the light receiving surface bus electrode 12B in the width direction connect the adjacent first regions 61 in the extension direction of the light receiving surface bus electrode 12B. Therefore, all the first region 61 and the second region 62 in one light receiving surface bus electrode 12B are electrically connected.

Further, the lead wire 20 is soldered to the light receiving surface bus electrode 12B mainly by soldering the first region 61 and the lead wire 20. Therefore, the soldering area between the light receiving surface bus electrode 12B and the lead wire 20 is approximated to the soldering area between the first region 61 and the lead wire 20.

By providing the light receiving surface bus electrode 12B with a plurality of through holes 60, the amount of the electrode material used for the light receiving surface bus electrode 12B can be reduced, and the manufacturing cost of the solar cell 10 can be reduced.

Further, the dimensions and positions of the through holes 60 may be adjusted to the dimensions and positions of the back surface connection electrode 13B, which will be described later. The dimensions and positions of the back surface connection electrode 13B are determined in consideration of the characteristics of the solar cell 10.

Further, the increase in the electrical resistance of the light receiving surface bus electrode 12B due to the provision of the through hole 60 in the light receiving surface bus electrode 12B can be suppressed by increasing the height of the light receiving surface bus electrode 12B.

Further, as shown in FIG. 11, the light receiving surface bus electrode 12B has the same width in the longitudinal direction, the width in the first region 61 and the width in the second region 62 are equal, and both ends in the second direction. The portion has a linear shape parallel to the first direction. The second direction corresponds to the Y direction in FIG. Then, when the lead wire 20 is connected to the electrode of the solar cell 10 to manufacture the solar cell module 100, the lead wire 20 having the same width as the light receiving surface bus electrode 12B is positioned at the light receiving surface in the second direction. It is soldered to the light receiving surface bus electrode 12B in a state of being overlapped on the light receiving surface bus electrode 12B in accordance with the bus electrode 12B.

FIG. 12 is a plan view showing a state in which the lead wire 20 is soldered onto the light receiving surface bus electrode 12B of the solar cell 10 according to the first embodiment of the present invention. FIG. 13 is a cross-sectional view showing the configuration of the solar cell 10 according to the first embodiment of the present invention, and is a cross-sectional view of a main part of the line XIII-XIII in FIG. FIG. 14 is a cross-sectional view showing the configuration of the solar cell 10 according to the first embodiment of the present invention, and is a cross-sectional view of a main part of the line XIV-XIV in FIG.

As shown in FIGS. 13 and 14, the lead wire 20 is overlapped on the light receiving surface bus electrode 12B at a position parallel to the light receiving surface bus electrode 12B and overlapping the light receiving surface bus electrode 12B in the width direction of the lead wire 20. It is arranged and soldered to the upper surface of the light receiving surface bus electrode 12B. That is, the lead wire 20 is soldered to the light receiving surface bus electrode 12B in a state where the side surface 20b in the width direction of the lead wire overlaps the side surface 12Ba of the light receiving surface bus electrode in the width direction in the second direction. The longitudinal direction of the lead wire 20 soldered to the light receiving surface bus electrode 12B is the same as the longitudinal direction of the light receiving surface bus electrode 12B, and is the same direction as the first direction described above, that is, the X direction. The width direction of the lead wire 20 soldered to the light receiving surface bus electrode 12B is the same direction as the width of the light receiving surface bus electrode 12B, and is the same direction as the second direction described above, that is, the Y direction.

As shown in FIG. 12, the lead wire 20 has the same width in the longitudinal direction, and is configured to have the same width as the width of the light receiving surface bus electrode 12B. Therefore, as shown in FIG. 13, in the plurality of second regions 62 provided with the through holes 60, the width of the lead wire 20 is the width of the second region 62, that is, the two connections facing each other in the second direction. It has the same dimensions as the length between the outer side surfaces 63a of the portion. The outer side surface 63a of the connection portion corresponds to the side surface 12Ba of the light receiving surface bus electrode in the second region 62. As shown in FIG. 14, in the plurality of first regions 61 in which the through holes 60 are not provided, the width of the lead wire 20 is the width of the first region 61, that is, the length of the first region 61 in the second direction. It has the same dimensions.

Soldering of the lead wire 20 to the light receiving surface bus electrode 12B in the plurality of second regions 62 provided with the through holes 60 is performed with the connecting portion 63 provided in the outer edge region of the light receiving surface bus electrode 12B in the width direction. Soldering to the wire 20 is performed at both ends of the lead wire 20 in the width direction.

The width of the light receiving surface bus electrode 12B is 0.6 mm or more and 1.2 mm or less. The width of the light receiving surface grid electrode 12G is 30 μm or more and 80 μm or less. The width of the connecting portion 63 is 60 μm or more and 160 μm or less. The width of the connecting portion 63 is about 1/15 or more and 1/5 or less with respect to the width of the light receiving surface bus electrode 12B. When the width of the light receiving surface bus electrode 12B is within the above range, the amount of electrode material used for the light receiving surface bus electrode 12B is reduced, and the electricity of the light receiving surface bus electrode 12B is caused by providing the through hole 60. Considering the increase in resistance, the width of the connecting portion 63 is most preferably about 1/10 of the width of the light receiving surface bus electrode 12B.

When the width of the light receiving surface grid electrode 12G is within the above range, the width of the connecting portion 63 is about twice the width of the light receiving surface grid electrode 12G. Considering the reduction in the amount of electrode material used for the light-receiving surface bus electrode 12B and the increase in electrical resistance of the light-receiving surface bus electrode 12B due to the provision of the through hole 60, the width of the connection portion 63 is set to receive light. Although it depends on the height of the surface bus electrode 12B, the width of about twice the width of the light receiving surface grid electrode 12G is most preferable.

When the width of the light receiving surface grid electrode 12G is thinned, if the number of light receiving surface grid electrodes 12G is increased by the amount of thinning the width of the light receiving surface grid electrode 12G, the amount of light received and the electrode resistance loss are the same. Since the distance flowing through the n-type impurity diffusion layer 2 before the carrier reaches the light receiving surface grid electrode 12G is shortened, the resistance loss in the n-type impurity diffusion layer 2 is reduced. Therefore, thinning the width of the light receiving surface grid electrode 12G is preferable from the viewpoint of resistance loss. However, the lower limit width of the light receiving surface grid electrode 12G is selected due to manufacturing restrictions. In particular, when the light receiving surface grid electrode 12G is formed by inexpensive screen printing, the lower limit width of the light receiving surface grid electrode 12G that can be formed by thinning is limited to 30 μm or more and 100 μm or less.

The width of the connecting portion 63 is also preferably thinned from the viewpoint of reducing the amount of electrode material used. However, the lower limit width is selected due to manufacturing restrictions and restrictions on the characteristics of the solar cell 10. The light receiving surface grid electrode 12G and the connecting portion 63 are simultaneously printed by screen printing using one printing mask together with the light receiving surface bus electrode 12B. Therefore, the height of the light receiving surface grid electrode 12G, the height of the connecting portion 63, and the height of the light receiving surface bus electrode 12B printed by screen printing are about the same. When the height of the light receiving surface grid electrode 12G and the height of the connecting portion 63 are the same, the amount of current flowing through the connecting portion 63 to several, that is, a few to five or six light receiving surface grid electrodes 12G. The width of the connecting portion 63 is preferably about twice as large as that of the light receiving surface grid electrode 12G.

As described above, both ends of the light receiving surface bus electrode 12B in the second direction are linear in parallel with the first direction. That is, the light receiving surface bus electrode 12B has a linear shape in which the outer side surfaces 63a of the two connecting portions facing each other in the second direction are parallel to the first direction. Then, when the lead wire 20 is connected to the electrode of the solar cell 10 to manufacture the solar cell module 100, the light receiving surface bus electrode 12B has a side surface of the light receiving surface bus electrode in the width direction in the second direction. The lead wire 20 is soldered to 12Ba with the side surface 20b in the width direction of the lead wire overlapping. That is, the position of the side surface 12Ba of the light receiving surface bus electrode and the position of the side surface 20b in the width direction of the lead wire are the same positions in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11.

Therefore, in the state where the lead wire 20 is soldered to the light receiving surface bus electrode 12B, the connecting portion 63 does not protrude outward from the first region 61. That is, with the lead wire 20 soldered to the light receiving surface bus electrode 12B, the connecting portion 63 is included in the lead wire 20 in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11.

Therefore, the solar cell 10 is caused by the presence of the connecting portion 63 in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11 so as to protrude from the lead wire 20 without being soldered to the lower surface of the lead wire 20. Therefore, it is possible to prevent a decrease in the amount of light received by the solar cell 10. That is, it is possible to prevent a decrease in the light receiving area due to the light receiving surface bus electrode 12B protruding from the lead wire 20 forming an unnecessary shadow on the light receiving surface 11A of the semiconductor substrate 11 and prevent a decrease in photoelectric conversion efficiency.

For example, when the connecting portion 63 is provided so as to project outward from the first region 61 in the second direction, the connecting portion 63 has an area protruding from the lead wire 20 connected to the light receiving surface bus electrode 12B. Therefore, the amount of light received by the solar cell 10 decreases, which causes a decrease in photoelectric conversion efficiency.

Further, since both ends of the light receiving surface bus electrode 12B in the second direction are linear in parallel with the first direction, the connecting portion 63 connects the first regions 61 adjacent to each other in the first direction. The semiconductor substrate 11 is connected at the shortest distance in the in-plane direction. Therefore, it is possible to suppress the resistance loss in the second region 62 caused by the photocurrent collected in the light receiving surface bus electrode 12B flowing through the connecting portion 63 having a width narrower than that of the first region 61.

Further, when the light receiving surface grid electrode 12G and the lead wire 20 are soldered, the stress at the time of soldering may be concentrated on the light receiving surface grid electrode 12G and the light receiving surface grid electrode 12G may be disconnected. In the solar cell 10, the connecting portion 63 is soldered to the lead wire 20 in the second region 62, and the light receiving surface grid electrode 12G and the lead wire 20 are not soldered. Therefore, the solar cell 10 can suppress disconnection of the light receiving surface grid electrode 12G due to soldering of the light receiving surface grid electrode 12G and the lead wire 20.

Further, in the solar cell 10, when the lead wire 20 is connected to the electrode of the solar cell 10 to manufacture the solar cell module 100, a general lead wire 20 having the same width in the longitudinal direction can be used. Therefore, the lead wire 20 having a shape dedicated to the solar cell 10 is unnecessary.

The solar cell module 100 uses a general lead wire 20 having the same width in the longitudinal direction. As a result, when the lead wire 20 is soldered to the solar cell 10, the positioning of the solar cell 10 and the lead wire 20 in the longitudinal direction of the light receiving surface bus electrode 12B and the lead wire 20, that is, the light receiving surface bus electrode Positioning of the 12B and the lead wire 20 becomes unnecessary. Therefore, the solar cell module 100 is easy to manufacture because the light receiving surface bus electrode 12B and the lead wire 20 can be soldered at an arbitrary position in the longitudinal direction of the light receiving surface bus electrode 12B and the lead wire 20.

On the other hand, on the back surface 11B side of the semiconductor substrate, as shown in FIGS. 6 and 8, a back surface current collecting electrode 13A containing aluminum (Al) and a plurality of dot-shaped back surface connecting electrodes 13B containing silver (Ag) are formed. , Consists of the back surface electrode 13. Further, around the region in contact with the back surface current collecting electrode 13A on the front surface layer of the back surface of the semiconductor substrate 1, there is a back surface electric field layer for improving the open circuit voltage and the short circuit current, and aluminum is formed from the back surface current collecting electrode 13A on the back surface of the semiconductor substrate 1. A back surface electric field (BSF: Back Surface Field) layer 4, which is a p + region diffused at a high concentration, is formed on the surface layer on the side.

The back surface current collecting electrode 13A is an electrode provided for forming the BSF layer 4 and for collecting the photocurrent generated by the solar cell 10 from the back surface 11B side of the semiconductor substrate 11, and is the back surface of the solar cell 10. Covers almost the entire area of. The back surface current collecting electrode 13A is a paste electrode formed by applying a conductive paste having metal particles of Al, which is an electrode material, to a desired range and firing.

Further, the back surface connection electrode 13B is an electrode provided for taking out the photocurrent collected by the back surface current collector electrode 13A to the outside and making contact with the external electrode. That is, the back surface connection electrode 13B is an electrode provided for joining with the lead wire 20. The back surface connection electrode 13B is provided along the first direction, which is the connection direction of the solar cell 10, like the light receiving surface bus electrode 12B. The back surface connection electrode 13B is a paste electrode formed by applying a conductive paste having metal particles of Ag, which is an electrode material, to a desired range and firing.

The back surface connection electrode 13B is arranged at a position facing the light receiving surface bus electrode 12B with the semiconductor substrate 11 interposed therebetween. Further, as shown in FIG. 8, the back surface connection electrodes 13B are dispersed and arranged in a flying stone shape over substantially the entire length of the solar cell 10 along the first direction which is the connecting direction of the solar cell 10. It is provided in a row. By forming the back surface connection electrode 13B in a stepping stone shape, the amount of silver used can be suppressed and the manufacturing cost can be suppressed.

Then, as shown in FIGS. 9 and 10, the position of the back surface connection electrode 13B is the position of the through hole 60 in the light receiving surface bus electrode 12B in the in-plane direction of the solar cell 10, that is, the in-plane direction of the semiconductor substrate 11. It is said that the position does not match. In other words, the first region 61 of the light receiving surface bus electrode 12B and the back surface connecting electrode 13B are arranged at positions facing each other in the thickness direction of the semiconductor substrate 11 via the semiconductor substrate 11. Therefore, the first region 61 of the light receiving surface bus electrode 12B and the back surface connecting electrode 13B are arranged at corresponding positions in the plane of the semiconductor substrate 11.

Therefore, in one solar cell 10, the lead wire 20 soldered to the light receiving surface bus electrode 12B on the light receiving surface side and the lead wire 20 connected to the back surface connecting electrode 13B on the back surface side are the solar cell 10 Soldered to the solar cell 10 at the same position in the in-plane direction of the semiconductor substrate 11, that is, in the in-plane direction of the semiconductor substrate 11. That is, in one solar cell 10, the lead wire 20 soldered to the light receiving surface side of the solar cell 10 and the lead wire 20 soldered to the back surface side of the solar cell 10 are the semiconductor substrate 11. Soldered at opposite positions in the thickness direction.

Then, by making the area of the first region 61 of the light receiving surface bus electrode 12B and the area of the back surface connecting electrode 13B substantially the same in the in-plane direction of the solar cell 10, the light receiving surface bus electrode 12B and the lead wire 20 are formed. The soldering area of the back surface connection electrode 13B and the soldering area of the lead wire 20 are substantially equal to each other.

As a result, in the solar cell 10 according to the first embodiment, the lead wire 20 and the light receiving surface bus when the lead wire 20 is soldered to the solar cell 10 in order to form the plurality of solar cell 10s. Most of the internal stress generated in the connection portion with the electrode 12B and the connection portion between the lead wire 20 and the back surface connection electrode 13B can be offset.

When the lead wire 20 is connected to the electrode of the solar cell 10 to manufacture the solar cell module 100, the lead wire 20 is soldered to the light receiving surface bus electrode 12B and the back surface connection electrode 13B as shown in FIGS. 9 and 10. Be attached. When the light receiving surface bus electrode 12B does not have the through hole 60 and the back surface connecting electrodes 13B are dispersed in a flying stone shape, the area of the light receiving surface bus electrode 12B in the plane of the semiconductor substrate 11 and the semiconductor The difference from the area of the back surface connection electrode 13B in the plane of the substrate 11 becomes large. Therefore, the internal stress generated at the connection portion between the lead wire 20 and the light receiving surface bus electrode 12B caused by the soldering of the lead wire 20 at the time of manufacturing the solar cell module 100, and the lead wire 20 and the back surface connecting electrode 13B The difference between the internal stress generated at the connection with and the internal stress becomes large. In this case, the internal stress generated at the connection portion between the lead wire 20 and the light receiving surface bus electrode 12B on the light receiving surface side of the solar cell 10 and the connection between the lead wire 20 and the back surface connecting electrode 13B on the back surface side of the solar cell 10. The internal stress generated in the portion is not balanced, and the difference in the internal stress causes the solar cell 10 to warp.

As a result, warpage occurs due to the difference in the coefficient of thermal expansion between the lead wire 20 made of metal and the silicon of the semiconductor substrate 11. Generally, the coefficient of thermal expansion of the metal constituting the lead wire 20 is larger than the coefficient of thermal expansion of silicon. Therefore, when the light receiving surface bus electrode 12B does not have the through hole 60 and the back surface connecting electrodes 13B are dispersed in a flying stone shape, that is, the area of the light receiving surface bus electrode 12B in the plane of the semiconductor substrate 11 is a semiconductor. When the area of the back surface connection electrode 13B in the surface of the substrate 11 is larger than the area of the back surface connection electrode 13B, the solar cell 10 is warped to be convex on the back surface side after soldering.

On the other hand, in the solar cell 10, the first region 61 of the light receiving surface bus electrode 12B and the back surface connecting electrode 13B are arranged at corresponding positions in the surface of the semiconductor substrate 11 and in the in-plane direction of the solar cell 10. In the above, the area of the first region 61 of the light receiving surface bus electrode 12B and the area of the back surface connecting electrode 13B are substantially the same, so that the soldering area between the light receiving surface bus electrode 12B and the lead wire 20 and the back surface connection The soldering area of the electrode 13B and the lead wire 20 becomes substantially equal. As a result, the fixed position of the light receiving surface bus electrode 12B and the lead wire 20 by soldering and the fixed position of the back surface connection electrode 13B and the lead wire 20 by soldering become the same position in the plane of the semiconductor substrate 11. In the solar cell 10, it is possible to balance the above-mentioned internal stresses on the light receiving surface side and the back surface side of the solar cell 10. Therefore, the solar cell 10 can suppress the warp of the solar cell 10 due to the soldering of the lead wire 20 to the solar cell 10 at the time of manufacturing the solar cell module 100. Therefore, the solar cell 10 can reduce the damage rate of the solar cell 10 due to the warp of the solar cell 10 at the time of manufacturing the solar cell module 100.

Then, by making the area of the first region 61 of the light receiving surface bus electrode 12B and the area of the back surface connecting electrode 13B exactly the same in the in-plane direction of the solar cell 10, the light receiving surface of the solar cell 10 is set to exactly the same area. It is possible to accurately balance the above-mentioned internal stresses on the side and the back surface side.

Further, in the solar cell 10, since the warpage of the solar cell 10 at the time of manufacturing the solar cell module 100 can be suppressed as described above, it is possible to cope with the thinning of the semiconductor substrate 11, and the thinner semiconductor. By using the substrate 11, the cost of the semiconductor substrate 11 can be reduced, and it is possible to realize an inexpensive solar cell 10.

The configuration of the solar cell 10 according to the first embodiment described above is an example, and the structure of the bulk type solar cell is not limited to the above description.

Further, in FIGS. 7 and 8, a case where the light receiving surface bus electrode 12B and the back surface connecting electrode 13B are four is shown as a typical example, but the number of the light receiving surface bus electrode 12B and the back surface connecting electrode 13B is as described above. Not limited to the description.

Next, a method for manufacturing the solar cell 10 according to the first embodiment will be described with reference to FIGS. 15 to 22. FIG. 15 is a flowchart illustrating a procedure of a manufacturing process of the solar cell 10 according to the first embodiment of the present invention. 16 to 22 are cross-sectional views of a main part showing a manufacturing process of the solar cell 10 according to the first embodiment of the present invention. It should be noted that FIGS. 20 to 22 show a diagram corresponding to FIG.

First, as the semiconductor substrate 1, as shown in FIG. 16, for example, a square p-type single crystal silicon substrate most often used for consumer solar cells is prepared. Here, the thickness and dimensions of the semiconductor substrate 1 are not particularly limited, but as an example, the thickness of the semiconductor substrate 1 is 200 μm, and the external dimensions of the semiconductor substrate 1 in the plane direction are 156 mm × 156 mm.

Since the semiconductor substrate 1 is manufactured by slicing a silicon ingot formed by cooling and solidifying molten silicon with a wire saw, damage during slicing remains on the surface. Therefore, first, the semiconductor substrate 1 is immersed in an acid solution or a heated alkaline solution and the surface is etched to remove the damaged layer, so that the semiconductor substrate 1 is generated when the semiconductor substrate 1 is cut out and is near the surface of the semiconductor substrate 1. Remove the existing damage area. An example of an alkaline solution is an aqueous sodium hydroxide solution.

Next, in step S10, minute irregularities (not shown) are formed on the surface of the semiconductor substrate 1 on the light receiving surface side as a texture structure. The fine irregularities are formed, for example, by immersing the semiconductor substrate 1 in a mixed solution of sodium hydroxide and isopropyl alcohol, which are an alkaline aqueous solution, and performing wet etching of the semiconductor substrate 1.

Next, in step S20, the semiconductor substrate 1 having fine irregularities formed on the surface as a texture structure is put into a heat diffusion furnace and heated in an atmosphere of phosphorus (P), which is an n-type impurity, to form the semiconductor substrate 1. A pn junction is formed on the entire surface. By this step, phosphorus is diffused from the surface of the semiconductor substrate 1 to the semiconductor substrate 1, and as shown in FIG. 17, an n-type impurity diffusion layer 2 is formed on the surface layer of the semiconductor substrate 1 to form a pn junction. As a result, the semiconductor substrate 11 having the pn junction formed is obtained.

To form the n-type impurity diffusion layer 2, for example, the semiconductor substrate 1 is put into a thermal diffusion furnace, and in a mixed atmosphere of phosphorus oxychloride (POCl ₃ ) gas and oxygen gas, for example, at a temperature of about 750 ° C. to 900 ° C. It is done by heating. The concentration of phosphorus diffused on the surface layer of the semiconductor substrate 1 can be controlled by conditions such as the concentration of phosphorus oxychloride, the ambient temperature, and the heating time. Here, on the surface of the n-type impurity diffusion layer 2 after formation, a phosphorus glass layer (not shown), which is a mixture of a silicon oxide film containing a phosphorus oxide as a main component and a phosphorus oxide, is formed. Therefore, the phosphorus glass layer on the surface of the n-type impurity diffusion layer 2 is removed by using a chemical such as a hydrofluoric acid aqueous solution.

Next, in step S30, a pn separation step of electrically insulating the back surface electrode 13 which is a p-type electrode and the light receiving surface electrode 12 which is an n-type electrode is performed, and as shown in FIG. 18, the semiconductor substrate 11 The n-type impurity diffusion layer 2 at the end is removed. Since the n-type impurity diffusion layer 2 is uniformly formed on the front surface of the semiconductor substrate 1, the light receiving surface 11A and the back surface 11B of the semiconductor substrate 11 are in a state of being electrically connected. Therefore, when the back surface electrode 13 and the light receiving surface electrode 12 are formed on the semiconductor substrate 11, the back surface electrode 13 and the light receiving surface electrode 12 are electrically connected. Pn separation is performed to break this electrical connection. Examples of the pn separation include end face etching using plasma etching and melt separation using laser processing.

Next, in step S40, for example, nitriding as an antireflection film 3 on the light receiving surface side of the semiconductor substrate 11, that is, on the n-type impurity diffusion layer 2 for surface protection and improvement of photoelectric conversion efficiency, as shown in FIG. A silicon (SiN) film is formed. For the formation of the antireflection film 3, for example, a plasma-enhanced chemical vapor deposition (PECVD) method is used, and a silicon nitride film is formed as the antireflection film 3 by using a mixed gas of silane and ammonia. To do. The film thickness and the refractive index of the antireflection film 3 are set to values that most suppress light reflection.

Next, the electrodes are formed. First, in step S50, the light receiving surface electrode 12 is printed on the light receiving surface side of the semiconductor substrate 11 by screen printing. That is, as shown in FIG. 20, the silver electrode paste 12a, which is an electrode material paste containing silver and glass frit, is printed in the shape of the light receiving surface electrode 12 on the antireflection film 3 on the light receiving surface side of the semiconductor substrate 11. To. Here, the silver electrode paste 12a is printed in the shape of the light receiving surface bus electrode 12B having the plurality of first regions 61 and the plurality of second regions 62 shown in FIGS. 7 and 11. Then, the silver electrode paste 12a is dried.

Next, in step S60, the back surface electrode 13 is printed on the back surface of the semiconductor substrate 11 by screen printing. It does not matter which of the backside current collecting electrode 13A and the backside connecting electrode 13B is printed first, but here, the case where the backside connecting electrode 13B is printed is shown.

First, as shown in FIG. 21, silver electrode paste 13b, which is an electrode material paste containing silver and glass frit, is printed on the back surface of the semiconductor substrate 11 in the shape of the back surface connection electrode 13B. The silver electrode paste 13b is a printing mask having an opening pattern at a position corresponding to the position where the first region 61 of the light receiving surface bus electrode 12B on the light receiving surface of the semiconductor substrate 11 is formed in the surface of the back surface of the semiconductor substrate 11. Printed using. Then, the silver electrode paste 13b is dried at a temperature of 200 ° C. for 5 minutes.

Next, as shown in FIG. 21, an aluminum electrode paste 13a, which is an electrode material paste containing aluminum and glass frit, is printed on the back surface of the semiconductor substrate 11 in the shape of the back surface current collecting electrode 13A. The aluminum electrode paste 13a is printed on the back surface of the semiconductor substrate 11 using a printing mask having an opening pattern on the entire back surface excluding a part of the print area and the outer edge region of the back surface connection electrode 13B. The aluminum electrode paste 13a is printed in a state where at least a part thereof is electrically connected to the silver electrode paste 13b. Then, the aluminum electrode paste 13a is dried at a temperature of 200 ° C. for 5 minutes.

Then, in step S70, electrode firing is performed to perform the firing process of the printed paste. By firing the electrode paste printed on the semiconductor substrate 11, as shown in FIG. 22, the light receiving surface grid electrode 12G and the light receiving surface bus electrode 12B as the light receiving surface electrode 12, and the back surface current collecting electrode 13A as the back surface electrode 13 are used. And the back surface connection electrode 13B. Baking is carried out in an air atmosphere at 750 ° C. or higher and 900 ° C. or lower using an infrared heating furnace. The firing temperature is selected in consideration of the structure of the solar cell 10 and the type of electrode paste.

By firing, on the light-receiving surface side of the semiconductor substrate 11, silver of the light-receiving surface electrode 12 fires through the antireflection film 3 which is an insulating film and penetrates therethrough, and the n-type impurity diffusion layer 2 and the light-receiving surface electrode 12 are electrically connected. Connect to. As a result, the n-type impurity diffusion layer 2 can obtain a good resistance bond with the light receiving surface electrode 12.

On the other hand, on the back surface side of the semiconductor substrate 11, the aluminum electrode paste 13a and the silver electrode paste 13b are fired to form the back surface current collecting electrode 13A and the back surface connection electrode 13B, and the illustration is made of aluminum and silver. No alloy part is formed.

When the back surface current collecting electrode 13A is formed, the aluminum electrode paste 13a also reacts with the p-type single crystal silicon on the back surface of the semiconductor substrate 11 and solidifies after the reaction to solidify the BSF layer 4 which is a p + layer containing aluminum. Is formed. That is, the region of the n-type impurity diffusion layer 2 formed on the back surface 11B side of the semiconductor substrate 11 immediately below the back surface current collector electrode 13A is changed to the BSF layer 4 by the diffusion of aluminum. Further, in the n-type impurity diffusion layer 2 formed on the back surface side of the semiconductor substrate 11, the region other than directly below the back surface current collector electrode 13A is a p-type region in which aluminum is diffused.

Next, a method of manufacturing the solar cell module 100 including the solar cell 10 according to the first embodiment will be described. FIG. 23 is a flowchart showing the procedure of the manufacturing method of the solar cell module 100 according to the first embodiment of the present invention.

First, in step S110, a plurality of solar cells are joined by soldering the lead wires 20 to the light receiving surface bus electrode 12B of one solar cell 10 and the back surface connecting electrode 13B of the other solar cell 10. 10 are electrically connected by lead wires 20 to form a solar cell string 50.

Next, in step S120, the sheet of the light receiving surface side sealing material 33, the solar cell string 50, the sheet of the back surface side sealing material 34, and the back surface protecting portion 32 are sequentially laminated on the light receiving surface protection portion 31, and the laminated body. Is formed.

Next, in step S130, the laminate is attached to the laminating apparatus, and heat treatment and laminating treatment are performed for about 30 minutes at a temperature of 140 ° C. or higher and 160 ° C. or lower. As a result, each member of the laminated body is integrated via the light receiving surface side sealing material 33 and the back surface side sealing material 34, and the solar cell module 100 is obtained.

After that, the outer edge portion of the solar cell module 100 is held by the frame 40 over the entire circumference.

As described above, the solar cell 10 according to the first embodiment is provided with a plurality of through holes 60 in the light receiving surface bus electrode 12B. As a result, in the solar cell 10, it is possible to reduce the amount of the electrode material used for the light receiving surface bus electrode 12B, and it is possible to reduce the manufacturing cost of the solar cell 10.

Further, in the solar cell 10 according to the first embodiment, the first region 61 of the light receiving surface bus electrode 12B and the back surface connecting electrode 13B are arranged at corresponding positions in the plane of the semiconductor substrate 11, and the semiconductor substrate 11 They are opposed to each other in the thickness direction of the semiconductor substrate 11. As a result, the solar cell 10 can suppress the warp of the solar cell 10 due to the soldering of the lead wire 20 to the solar cell 10 at the time of manufacturing the solar cell module 100, and the solar cell module 100 can suppress the warp of the solar cell 10. It is possible to reduce the damage rate of the solar cell 10 due to the warp of the solar cell 10 at the time of manufacture.

Further, in the solar cell 10 according to the first embodiment, the light receiving surface bus electrode 12B has the same width in the longitudinal direction, and both ends in the second direction are linear in parallel with the first direction. The width of the light receiving surface bus electrode 12B is the same as the width of the lead wire 20 connected to the width of the light receiving surface bus electrode 12B and having the same width in the longitudinal direction. When the solar cell module 100 is manufactured, the positions of the side surface 12Ba of the light receiving surface bus electrode 12B on both sides of the light receiving surface bus electrode 12B in the second direction and the width direction of the lead wires on both sides of the lead wire 20 in the second direction. Is the same position as the position of the side surface 20b of the semiconductor substrate 11 in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11. The position of the side surface 12Ba of the light receiving surface bus electrode and the position of the side surface 20b in the width direction of the lead wire are the same positions in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11. As a result, the solar cell 10 prevents a decrease in the amount of light received by the solar cell 10 due to the light receiving surface bus electrode 12B protruding from the lead wire 20 in the in-plane direction of the light receiving surface 11A of the semiconductor substrate 11. It is possible to prevent a decrease in photoelectric conversion efficiency.

Further, since the solar cell 10 can suppress the warp of the solar cell 10 at the time of manufacturing the solar cell module 100, the cost of the semiconductor substrate 11 can be reduced by using the thinner semiconductor substrate 11, and the inexpensive solar cell 10 can be used. It is possible to correspond to the realization of.

Therefore, according to the solar cell 10 according to the first embodiment, it is possible to suppress the warp of the solar cell due to the joining of the lead wire to the solar cell.

Embodiment 2.
FIG. 24 is a plan view of the solar cell 110 according to the second embodiment of the present invention as viewed from the light receiving surface side. FIG. 25 is a plan view of the solar cell 110 according to the second embodiment of the present invention as viewed from the back surface side facing the light receiving surface side and the opposite side. FIG. 26 is a cross-sectional view of a main part showing the configuration of the solar cell module according to the second embodiment of the present invention. FIG. 26 is a view corresponding to FIG. 3, and is a cross-sectional view of a main part of the solar cell module according to the second embodiment, which is composed of the solar cell 110. The cross-sectional view of the solar cell 110 in FIG. 26 is a cross-sectional view of a main part in the line XXIII-XXIII in FIG. 24. FIG. 27 is a diagram showing the configuration conditions of the light receiving surface electrode 112 of the solar cell 110 according to the second embodiment of the present invention. FIG. 28 is a diagram showing the configuration conditions of the back surface connection electrode 113B of the solar cell 110 according to the second embodiment of the present invention.

The solar cell 110 according to the second embodiment uses a light receiving surface grid electrode 12G and a light receiving surface bus electrode 112B instead of the light receiving surface electrode 12 composed of the light receiving surface grid electrode 12G and the light receiving surface bus electrode 12B. The light receiving surface electrode 112 is provided. Further, the solar cell 110 includes a back surface electrode 113 composed of the back surface current collecting electrode 13A and the back surface connecting electrode 113B instead of the back surface electrode 13 composed of the back surface current collecting electrode 13A and the back surface connecting electrode 13B. .. The solar cell 110 has the same configuration as the solar cell 10 according to the first embodiment, except that the light receiving surface electrode 112 and the back surface electrode 113 are configured. The same configuration as that of the solar cell 10 according to the first embodiment in the solar cell 110 is designated by the same reference numerals, and detailed description thereof will be omitted.

The light receiving surface bus electrode 112B is arranged differently from the light receiving surface bus electrode 12B. The back surface connection electrode 113B is arranged differently from the back surface connection electrode 13B.

Four light-receiving surface bus electrodes 112B are provided in the solar cell 110. The solar cell 110 has a semiconductor substrate 11 having a rectangular shape, and has a first end edge portion and a second end edge portion which are a pair of parallel end portions. Here, the first end side portion is the side on the one end 101 side, which is one end portion of the solar cell 110 in the first direction. The second end side is the other end of the solar cell 110 in the first direction, parallel to one end 101, and the other end 102 side opposite to the one end 101 in the first direction. Is. In each light receiving surface bus electrode 112B, the first region 611, the first region 612, the first region 613, and the first region 614 are directed from one end 101 side to the other end 102 side of the solar cell 110 in the first direction. , The first region 615, the first region 616, the first region 617, and the first region 618 are arranged.

Here, one end 101 side of the solar cell 110 in the first direction is the end side on the side where the adjacent solar cell 110 to which the light receiving surface bus electrode 112B is connected by the lead wire 20 is arranged. Corresponds to the left side of the solar cell 110 in FIGS. 24 to 26. In the solar cell 110, the end on the side where the adjacent solar cell 110 to which the light receiving surface bus electrode 112B is connected by the lead wire 20 is arranged is the end on the light receiving surface side on the interconnection side.

Further, the other end 102 side of the solar cell 110 in the first direction is the end side on the side where the adjacent solar cell 110 to which the light receiving surface bus electrode 112B is connected by the lead wire 20 is not arranged. Corresponds to the right side of the solar cell 110 in FIG. 26. In the solar cell 110, the end on the side where the adjacent solar cell 110 to which the light receiving surface bus electrode 112B is connected by the lead wire 20 is not arranged is the end on the light receiving surface side on the non-interconnecting side.

Further, the length of the first region in the longitudinal direction of the light receiving surface bus electrode 112B, that is, the length of the first region in the first direction is such that the length of the first region 611 is the length of the first region A1 and the first region. The length of 612 is the length of the first region A2, the length of the first region 613 is the length of the first region A3, the length of the first region 614 is the length of the first region A4, and the length of the first region 615 is The length of the first region A5, the length of the first region 616 is the length of the first region A6, the length of the first region 617 is the length of the first region A7, and the length of the first region 618 is the length of the first region. It is A8.

Further, in the first direction, the distance from one end 101 of the solar cell 110 to the first region 611 is the distance B1, the distance between the first region 611 and the first region 612 is the distance B2, and the first region 612. The distance between the first region 613 is the distance B3, the distance between the first region 613 and the first region 614 is the distance B4, the distance between the first region 614 and the first region 615 is the distance B5, and the first The distance between the 1st region 615 and the 1st region 616 is the distance B6, the distance between the 1st region 616 and the 1st region 617 is the distance B7, and the distance between the 1st region 617 and the 1st region 618 is The distance B8 is the distance from the first region 618 to the other end 102 of the solar cell 110.

Four back surface connection electrodes 113B are provided in the solar cell 110. The same number of back surface connection electrodes 113B as the number of the first region 61 of the light receiving surface bus electrode 112B are provided at positions corresponding to the first region 61 in the surface of the semiconductor substrate 11. In each back surface connection electrode 113B, the back surface connection electrode 1131, the back surface connection electrode 1132, the back surface connection electrode 1133, the back surface connection electrode 1134, from one end 101 side to the other end 102 side of the solar cell 110 in the first direction. The back surface connection electrode 1135, the back surface connection electrode 1136, the back surface connection electrode 1137, and the back surface connection electrode 1138 are arranged.

The back surface connection electrode 113B is arranged at a position corresponding to the first region 61 in the plane of the semiconductor substrate 11. Therefore, in the plane of the semiconductor substrate 11, the back surface connection electrode 1131 is located at a position corresponding to the first region 611, the back surface connection electrode 1132 is located at a position corresponding to the first region 612, and the back surface connection electrode 1133 is located at the first position. The back surface connection electrode 1134 is located at a position corresponding to the region 613, the back surface connection electrode 1134 is located at a position corresponding to the first region 614, the back surface connection electrode 1135 is located at a position corresponding to the first region 615, and the back surface connection electrode 1136 is located at the position corresponding to the first region 616. The back surface connection electrode 1137 is arranged at a position corresponding to the first region 617, and the back surface connection electrode 1138 is arranged at a position corresponding to the first region 618.

Here, one end 101 side of the solar cell 110 in the first direction described above is the end side on the side where the adjacent solar cell 110 to which the back surface connection electrode 113B is connected by the lead wire 20 is not arranged. In the solar cell 110, the end portion on the back surface side where the adjacent solar cell 110 to which the back surface connection electrode 113B is connected by the lead wire 20 is not arranged is the end portion on the back surface side on the non-interconnect side.

Further, the other end 102 side of the solar cell 110 in the first direction is the end side on the side where the adjacent solar cell 110 to which the back surface connection electrode 113B is connected by the lead wire 20 is arranged. In the solar cell 110, the end on the side where the adjacent solar cell 110 to which the back surface connection electrode 113B is connected by the lead wire 20 is arranged is the end on the back surface side on the interconnection side.

The length of the back surface connection electrode 113B in the first direction is such that the length of the back surface connection electrode 1131 is the back surface connection electrode length C1, the length of the back surface connection electrode 1132 is the back surface connection electrode length C2, and the back surface connection electrode 1133. Is the back surface connection electrode length C3, the back surface connection electrode 1134 is the back surface connection electrode length C4, the back surface connection electrode 1135 is the back surface connection electrode length C5, and the back surface connection electrode 1136 is the back surface. The length of the connection electrode is C6, the length of the back surface connection electrode 1137 is the back surface connection electrode length C7, and the length of the back surface connection electrode 1138 is the back surface connection electrode length C8.

Further, in the first direction, the distance from one end 101 of the solar cell 110 to the back surface connection electrode 1131 is the distance D1, the distance between the back surface connection electrode 1131 and the back surface connection electrode 1132 is the distance D2, and the back surface connection electrode 1132. The distance between the back surface connection electrode 1133 is the distance D3, the distance between the back surface connection electrode 1133 and the back surface connection electrode 1134 is the distance D4, the distance between the back surface connection electrode 1134 and the back surface connection electrode 1135 is the distance D5, and the back surface. The distance between the connection electrode 1135 and the back surface connection electrode 1136 is the distance D6, the distance between the back surface connection electrode 1136 and the back surface connection electrode 1137 is the distance D7, and the distance between the back surface connection electrode 1137 and the back surface connection electrode 1138 is. The distance D8 is the distance D9 from the back surface connection electrode 1138 to the other end 102 of the solar cell 110.

The semiconductor substrate 11 has a square shape of, for example, 156 mm square. The first region length A1, the first region length A2, the first region length A3, the first region length A4, the first region length A5, the first region length A6, and the first region length A7 are For example, it is 5 mm. The first region length A8 is longer than the first region length A1 to the first region length A7, for example, 11 mm. The distance B1 and the distance B9 are, for example, 0.5 mm. The distance B2 and the distance B8 are, for example, 7 mm. The distance B3, the distance B4, the distance B5, the distance B6 and the distance B7 are, for example, 19 mm.

Backside connection electrode length C1, backside connection electrode length C2, backside connection electrode length C3, backside connection electrode length C4, backside connection electrode length C5, backside connection electrode length C6, backside connection electrode length C7 and backside The connection electrode length C8 is, for example, 5 mm. The distance D9 is longer than the distance D1, and there is a relationship of distance D1 <distance D9. For example, the distance D1 = 0.5 mm and the distance D9 = 6.5 mm. The distance D2 and the distance D8 are, for example, 7 mm. The distance D3, the distance D4, the distance D5, the distance D6 and the distance D7 are, for example, 19 mm.

On the light receiving surface side of the solar cell 110, it is preferable to provide the light receiving surface bus electrodes 112B to both ends of the solar cell 110 in the first direction. On the other hand, on the back surface side of the solar cell 110, especially on the other end 102 side which is the lead wire connecting side, the distance from the end surface of the solar cell 110 to the back surface connecting electrode 113B can be increased in the first direction. preferable.

The light receiving surface side of the solar cell 110 has a convex curved surface. That is, since the back surface current collecting electrode 13A using the electrode material containing aluminum is formed on the entire back surface of the solar cell 110, warpage occurs in the solar cell 110 due to the difference in the coefficient of thermal expansion between aluminum and silicon. To do. In general, since the coefficient of thermal expansion of aluminum is larger than the coefficient of thermal expansion of silicon, the solar cell 110 is warped so as to be convex toward the light receiving surface side after the heat treatment of firing the electrodes.

When the lead wire 20 is soldered to the solar cell 110, the light receiving surface is convex, so that the light receiving surface of the solar cell 110 is perpendicular to the light receiving surface between the solar cell 110 and the lead wire 20. A stress is generated to peel off the lead wire 20. The peeling stress is greatest at the end of the solar cell 110.

Therefore, on the light receiving surface side of the solar cell 110, the light receiving surface bus electrodes 112B and the lead wires on the end side of the solar cell 110 are provided by providing the light receiving surface bus electrodes 112B to both ends of the semiconductor substrate 11 in the first direction. The bond strength between 20 and 20 can be increased. That is, as described above, the light receiving surface grid electrode 12G is formed up to a position where the distance B1 and the distance B9 are 0.5 mm in the first direction. Then, the light receiving surface bus electrodes 112B are provided up to the light receiving surface grid electrodes 12G at both ends in the first direction, and the light receiving surface bus electrodes 112B are provided up to the positions at both ends of the semiconductor substrate 11 in the first direction. As a result, the solar cell 110 can further strengthen the bonding strength between the light receiving surface bus electrode 112B and the lead wire 20 on the end side. By forming both ends of the light receiving surface bus electrode 112B in the first direction by the first region, it is possible to increase the joint strength between the light receiving surface bus electrode 112B and the lead wire 20 on the end side. .. When both ends of the light receiving surface bus electrode 112B in the first direction are formed by the second region 62, the end portion of the light receiving surface bus electrode 112B is soldered to the lead wire 20 only by the connecting portion 63. Bond strength decreases.

Further, in the solar cell 110, the semiconductor substrate 11 is a solar cell on the side opposite to the first end edge portion which is the end portion of the solar cell 110 in the first direction and the first end edge portion in the first direction. It has a rectangular shape having a second end edge portion which is an end portion of the cell 110. Then, the distance between the back surface connection electrode 113B adjacent to the second end edge portion and the second end edge portion is made longer than the distance between the back surface connection electrode 113B adjacent to the first end edge portion and the first end edge portion. ing.

The solar cell 10 according to the first embodiment described above has a configuration symmetrical with respect to the central position in the first direction in the first direction. Therefore, when the solar cells 10 are connected to each other by the lead wires 20, the lead wires 20 are arranged from the lower left to the upper right in the figure as shown in FIG. 3, and the adjacent solar cells 10 are connected to each other. , The lead wire 20 is arranged from the upper left to the lower right with respect to the adjacent solar cells 10 shown in FIG. 3, and the configuration is equivalent to the configuration in which the adjacent solar cells 10 are connected to each other.

On the other hand, the solar cell 110 according to the second embodiment has a configuration asymmetrical with respect to the central position in the first direction in the first direction. Therefore, when the solar cells 110 are connected to each other by the lead wires 20, the lead wires 20 are arranged from the lower left to the upper right in the figure as shown in FIG. 26, and the adjacent solar cells 110 are connected to each other. The lead wires 20 are arranged from the upper left to the lower right with respect to the adjacent solar cells 110 shown in FIG. 26, and the configuration is not equivalent to the configuration in which the adjacent solar cells 110 are connected to each other.

Here, the lead wire 20 is arranged from the lower left to the upper right, and the solar cells 10 on the left side of the solar cells 10 arranged on the left and right as shown in FIG. 3 are connected to each other. The back surface connection electrode 13B of the cell 10 and the light receiving surface bus electrode 12B of the right solar cell 10 are connected by a lead wire 20. Further, in the configuration in which the lead wires 20 are arranged from the upper left to the lower right and the adjacent solar cells 10 are connected to each other, the light receiving surface bus of the left solar cell 10 among the left and right solar cells 10 is arranged. The electrode 12B and the back surface connection electrode 13B of the right solar cell 10 are connected by a lead wire 20.

On the back surface side of the solar cell 110 having the above configuration, the other end 102 side of the solar cell 110, which is the end portion of the solar cell 110 on the interconnection side on the back surface side, is connected to the back surface from the end surface of the solar cell 110. By increasing the distance to the electrode 113B, that is, the distance D9 from the back surface connection electrode 1138 to the other end 102 of the solar cell 110, the following effects can be obtained.

As shown in FIG. 26, in the solar cell module according to the second embodiment, a plurality of solar cell 110s are connected by lead wires 20 from the back surface side of one solar cell 110a to the other solar cell 110b. The lead wire 20 is connected to the light receiving surface side of the above in a curved shape. That is, the solar cell module according to the second embodiment is the second end side portion of one solar cell 110 arranged on the left side in FIG. 26 and the other solar cell arranged on the right side in FIG. 26. The first end edge portion of the cell 110 is arranged so as to face each other, and one solar cell 110 and the other solar cell 110 are adjacent to each other in the first direction. Further, the solar cell module according to the second embodiment has a lead wire 20 for connecting the back surface connection electrode 113B of one solar cell 110 and the light receiving surface bus electrode 112B of the other solar cell 110. The lead wire 20 connects the back surface connection electrode 113B on the second end side of one solar cell 110 and the light receiving surface bus electrode 112B on the first end side of the other solar cell 110. To do.

The length of the bent portion 20a that bends the lead wire 20 in a curved shape by wiring the lead wire 20 from the back surface side of the solar cell 110a to the light receiving surface side of the adjacent solar cell 110b with the distance D1 <distance D9. Therefore, the bending radius of the bent portion 20a of the lead wire 20 becomes large, and the stress concentration of the lead wire 20 on the bent portion 20a is reduced. In particular, the solar cell module is designed with a life expectancy of 10 years or more, but due to the difference in linear expansion coefficient between the light receiving surface glass serving as the light receiving surface protection portion 31 and the lead wire 20, the day and night temperature Due to the cycle, repeated stress is generated in the bent portion 20a of the lead wire 20 to cause disconnection, which causes a failure. Here, by increasing the bending radius of the bent portion 20a of the lead wire 20, the repetitive stress applied to the bent portion 20a can be reduced, so that a solar cell module having excellent long-term reliability can be realized.

In the solar cell 110, the first region 61 other than the end side on the non-interconnect side on the light receiving surface side, that is, the first region 61 other than the other end 102 side, and the back surface connection electrode 113B are the light receiving surface and the back surface. It is preferable to provide it at the corresponding position. That is, it is preferable that the first region 611 to the first region 617 are provided at positions corresponding to the back surface connection electrodes 1131 to the back surface connection electrode 1137, respectively, in the plane of the solar cell 110. As a result, except for the first region 618 and the back surface connection electrode 1138, the fixed position of the light receiving surface bus electrode 112B and the lead wire 20 and the fixed position of the back surface connection electrode 113B and the lead wire 20 by soldering are semiconductors. The positions are the same in the plane of the substrate 11. As a result, the solar cell 110 suppresses warpage of the solar cell 110 due to soldering of the lead wire 20 to the solar cell 110 at the time of manufacturing the solar cell module, similarly to the above-mentioned solar cell 10. be able to. Therefore, the solar cell 110 can reduce the damage rate of the solar cell 110 due to the warp of the solar cell 110 at the time of manufacturing the solar cell module.

In the light receiving surface bus electrode 112B, the distance between adjacent first regions on the end side in the first direction includes the distance between adjacent first regions in the central portion of the first direction in the first direction. It is preferably shorter than the distance between adjacent first regions on the inner side. That is, in the light receiving surface bus electrode 112B, the length of the second region on the end side in the first direction is preferably shorter than the length of the second region on the inner side in the first direction. Therefore, (distance B2 = distance D2 = distance B8 = distance D8) <(distance B3 = distance D3, distance B4 = distance D4, distance B5 = distance D5, distance B6 = distance D6, distance B7 = distance D7). Is preferable.

As described above, when the lead wire 20 is soldered to the solar cell 110, the light receiving surface side of the solar cell 110 is convex, so that the sun is located between the solar cell 110 and the lead wire 20. The stress of peeling the lead wire 20 in the direction perpendicular to the light receiving surface of the battery cell 110 is greatest on the end side in the first direction. On the other hand, by making the length of the second region on the end side in the first direction shorter than the length of the second region on the inner side in the first direction, the end side in the first direction The bonding strength between the light receiving surface bus electrode 112B and the lead wire 20 can be increased.

As described above, in the solar cell 110 according to the second embodiment, except for the first region 618 and the back surface connection electrode 1138, the fixing positions of the light receiving surface bus electrode 112B and the lead wire 20 and the soldering are used. The fixed positions of the back surface connection electrode 113B and the lead wire 20 are the same in the plane of the semiconductor substrate 11. As a result, the solar cell 110 can reduce the damage rate of the solar cell 110 due to the warp of the solar cell 110 at the time of manufacturing the solar cell module, similarly to the solar cell 10 described above.

Further, in the solar cell 110 according to the second embodiment, the other end 102 side of the solar cell 110, which is the end portion on the back surface side of the solar cell 110 on the interconnection side, is from the end surface of the solar cell 110. Increase the distance to the back surface connection electrode 113B. As a result, the length of the bent portion 20a that bends the lead wire 20 connecting the adjacent solar cell 110s in a curved shape becomes long. As a result, the stress concentration of the lead wire 20 on the bent portion 20a can be reduced, and due to the difference in the coefficient of linear expansion between the light receiving surface glass serving as the light receiving surface protection portion 31 and the lead wire 20, day and night Since the repetitive stress applied to the bent portion 20a can be reduced by the temperature cycle, a solar cell module having excellent long-term reliability can be realized.

Embodiment 3.
FIG. 29 is a cross-sectional view showing the configuration of the solar cell 210 according to the third embodiment of the present invention. FIG. 29 is a cross section of the light receiving surface electrode 212 passing through the through hole 60 along the longitudinal direction, and the back surface current collecting electrode 13A is not shown for easy understanding. FIG. 30 is a diagram showing the configuration conditions of the light receiving surface electrode 212 of the solar cell 210 according to the third embodiment of the present invention. FIG. 31 is a diagram showing the configuration conditions of the back surface connection electrode 213B of the solar cell 210 according to the third embodiment of the present invention.

The solar cell 210 according to the third embodiment includes a light receiving surface electrode 212 having a light receiving surface bus electrode 212B instead of the light receiving surface bus electrode 112B. Further, the solar cell 210 according to the third embodiment includes a back surface electrode 213 having a back surface connection electrode 213B instead of the back surface connection electrode 113B. The solar cell 210 has the same configuration as the solar cell 110 according to the second embodiment except for the configuration of the light receiving surface electrode 212 and the back surface electrode 213. In the solar cell 210, the same components as those of the solar cell 10 according to the first embodiment or the solar cell 110 according to the second embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The light receiving surface bus electrode 212B is arranged differently from the light receiving surface bus electrode 112B. The back surface connection electrode 213B has a different arrangement from the back surface connection electrode 113B.

Similar to the light receiving surface bus electrode 112B, four light receiving surface bus electrodes 212B are provided in the solar cell 210. Further, in each light receiving surface bus electrode 212B, similarly to the light receiving surface bus electrode 112B, the first region 611, the first region 612, the first region 613, the first region 614, the first region 615, and the first region 616 , The first region 617 and the first region 618 are arranged along the first direction. Similar to the back surface connection electrode 113B, the back surface connection electrodes 213B are arranged in four rows along the first direction in a stepping stone shape over substantially the entire length of the solar cell 210. ..

The same number of back surface connection electrodes 213B as the number of the first region 61 of the light receiving surface bus electrode 212B are provided at positions corresponding to the first region 61 in the surface of the semiconductor substrate 11.

The first region 61 located on the light receiving surface bus electrode 212B other than the end side in the first direction, that is, located on the inner side in the first direction, and the back surface connection electrode 213B are the surfaces of the semiconductor substrate 11. When the semiconductor substrate 11 is viewed through from a direction perpendicular to the inward direction, the center position in the first direction is the same position. That is, in the first direction, the center position of the first region 612 is the same as the center position of the back surface connection electrode 1132. The center position of the first region 613 and the back surface connection electrode 1133, the center position of the first region 614 and the back surface connection electrode 1134, the center position of the first region 615 and the center position of the back surface connection electrode 1135. The same applies to the center position of the first region 616 and the back surface connecting electrode 1136, and the center position of the first region 617 and the center position of the back surface connecting electrode 1137.

On the other hand, the first region 611 located on the end side in the first direction of the light receiving surface bus electrode 212B and the back surface connection electrode 1131 see through the semiconductor substrate 11 from a direction perpendicular to the in-plane direction of the semiconductor substrate 11. In some cases, the center positions in the first direction are not the same. That is, in the first direction, the center position of the first region 611 is different from the center position of the back surface connection electrode 1131. Similarly, in the first direction, the center position of the first region 618 is different from the center position of the back surface connection electrode 1138.

The placement pitches of the two adjacent first regions 61 on the inner side in the first direction are all the same placement pitch. Further, the arrangement pitches of the two back surface connection electrodes 213B adjacent to each other on the inner side in the first direction are all the same arrangement pitch. The arrangement pitches of the two first regions 61 adjacent to each other on the inner side in the first direction and the arrangement pitches of the two back surface connection electrodes 213B adjacent to each other on the inner side in the first direction are the same arrangement pitch. .. The arrangement pitch of the first region 61 is the distance between the center positions of the first region 61 in the first direction. The arrangement pitch of the back surface connecting electrodes 213B is the distance between the center positions of the back surface connecting electrodes 213B in the first direction.

That is, the arrangement pitch between the first region 612 and the first region 613, the arrangement pitch between the first region 613 and the first region 614, the arrangement pitch between the first region 614 and the first region 615, and the first region 615 and the first region. Arrangement pitch with one region 616, arrangement pitch between the first region 616 and the first region 617, arrangement pitch between the back surface connection electrode 1132 and the back surface connection electrode 1133, arrangement pitch between the back surface connection electrode 1133 and the back surface connection electrode 1134, The arrangement pitch of the back surface connection electrode 1134 and the back surface connection electrode 1135, the arrangement pitch of the back surface connection electrode 1135 and the back surface connection electrode 1136, and the arrangement pitch of the back surface connection electrode 1136 and the back surface connection electrode 1137 are the same arrangement pitch.

The first region length A2, the first region length A3, the first region length A4, the first region length A5, the first region length A6, and the first region length A7 are the same. The back surface connection electrode length C2, the back surface connection electrode length C3, the back surface connection electrode length C4, the back surface connection electrode length C5, the back surface connection electrode length C6, and the back surface connection electrode length C7 are the same. The first region length A2 is longer than the back surface connection electrode length C2.

The distance B3, the distance B4, the distance B5, the distance B6 and the distance B7 are the same. The distance D3, the distance D4, the distance D5, the distance D6 and the distance D7 are the same. And the distance D3 is longer than the distance B3.

Therefore, (first region length A2 + distance B3) = (first region length A3 + distance B4) = (first region length A4 + distance B5) = (first region length A5 + distance B6) = (first region) Length A6 + Distance B7) = (Backside connection electrode length C2 + Distance D3) = (Backside connection electrode length C3 + Distance D4) = (Backside connection electrode length C4 + Distance D5) = (Backside connection electrode length C5 + Distance D6) = (Backside connection electrode length C6 + distance D7).

In order to match the center position of the first region 612 in the first direction with the center position of the back surface connection electrode 1132 in the first direction, one end 101 of the solar cell 210 to the first region 612 in the first direction. The distance to the center position of the solar cell 210 and the distance from one end 101 of the solar cell 210 to the center position of the back surface connection electrode 1132 are the same distance. That is, (distance B1 + first region length A1 + distance B2 + first region length A2 / 2) = (distance D1 + back surface connection electrode length C1 + distance D2 + back surface connection electrode length C2 / 2).

In order to match the center position of the first region 617 in the first direction with the center position of the back surface connection electrode 1137 in the first direction, the first region from the other end 102 of the solar cell 210 in the first direction. The distance to the center position of 617 and the distance from the other end 102 of the solar cell 210 to the center position of the back surface connection electrode 1137 are the same distance. That is, (distance B9 + first region length A8 + distance B8 + first region length A7 / 2) = (distance D9 + back surface connection electrode length C8 + distance D8 + back surface connection electrode length C7 / 2).

The first region length A1 is longer than the back surface connection electrode length C1. When the semiconductor substrate 11 is viewed through from a direction perpendicular to the in-plane direction of the semiconductor substrate 11, in the first direction, the back surface connection electrode 1131 overlaps the first region 611 inside the first region 611, that is, In the first direction, the back surface connection electrode 1131 is arranged at a position included in the first region 611.

The first region length A8 is longer than the back surface connection electrode length C8. When the semiconductor substrate 11 is viewed through from a direction perpendicular to the in-plane direction of the semiconductor substrate 11, in the first direction, the back surface connection electrode 1138 is located inside the first region 618 and overlaps the first region 618, that is, In the first direction, the back surface connecting electrode 1138 is arranged at a position included in the first region 618.

The back surface connection electrode length C1 and the back surface connection electrode length C8 are the same as the back surface connection electrode length C2.

In the first direction, the placement pitch of the two adjacent first regions 61 on the end side of the first direction is shorter than the placement pitch of the two adjacent first regions 61 on the inner side of the first direction. .. That is, in the light receiving surface bus electrode 212B, the distance between the two adjacent first regions 61 on the end side in the first direction is the distance between the two adjacent first regions 61 in the central portion in the first direction. Is shorter than the distance between two adjacent first regions 61 on the inner side in the first direction, including. Therefore, the distance B2 and the distance B8 are shorter than the distance B3, the distance B4, the distance B5, the distance B6 and the distance B7.

In the first direction, the arrangement pitch of the two adjacent back surface connecting electrodes 213B on the end side in the first direction is shorter than the arrangement pitch of the two adjacent back surface connecting electrodes 213B on the inner side in the first direction. .. That is, in the back surface connection electrode 213B in one row, the distance between the two back surface connection electrodes 213B adjacent to each other on the end side in the first direction is between the two back surface connection electrodes 213B adjacent to each other in the central portion in the first direction. It is shorter than the distance between two adjacent back surface connection electrodes 213B on the inner side in the first direction, including the distance between the two electrodes. Therefore, the distance D2 and the distance D8 are shorter than the distance D3, the distance D4, the distance D5, the distance D6 and the distance D7.

In the solar cell 210 according to the third embodiment, the total length of the first region of the light receiving surface bus electrode 212B in the first direction is the light receiving surface bus electrode 112B of the solar cell 110 according to the second embodiment. It is significantly longer than the total length of the first region of. That is, as shown in FIG. 30, the total length of the first region in the solar cell 210, that is, the total length from the first region length A1 to the first region length A8 is 76 mm. On the other hand, as shown in FIG. 27, the total length of the first region in the light receiving surface bus electrode 112B of the solar cell 110 according to the second embodiment, that is, from the first region length A1 to the first region length A8. The total is 46 mm.

Soldering of the lead wire 20 to the light receiving surface bus electrode 212B is mainly performed by soldering the first region 61 and the lead wire 20. Therefore, the length of the connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction is approximated to the total length of the first region. Therefore, the total length of the first region is considered to be the length of the connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction.

Further, in the solar cell 210 according to the third embodiment, the total length of the first region of the light receiving surface bus electrode 212B in the first direction is the total length of the back surface connection electrode 213B in the first direction. Longer than. Therefore, in the solar cell 210 according to the third embodiment, the length of the connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction is the back surface connection electrode 213B and the lead in the first direction. It is longer than the length of the connection area with the wire 20. That is, as shown in FIG. 31, the total from the back surface connection electrode length C1 to the back surface connection electrode length C8 is 48 mm. On the other hand, as shown in FIG. 30, the total length of the first region, that is, the total length from the first region length A1 to the first region length A8 is 76 mm.

In the solar cell 210, since the back surface current collecting electrode 13A using the electrode material containing aluminum is formed on the entire back surface of the solar cell 210, the solar cell 210 is placed on the light receiving surface side after the heat treatment for firing the electrodes. A convex warp occurs. Therefore, on the light receiving surface side of the solar cell 210, which is a convex curved surface, a stress for peeling the lead wire 20 is applied between the electrode and the lead wire 20 more than on the back surface side of the solar cell 210.

In the solar cell 210, the length of the connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction is longer than the length of the back surface connection electrode 213B in the first direction. Then, in the solar cell 210, the length of the connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction is the light receiving in the first direction in the solar cell 110 according to the second embodiment. It is longer than the length of the connection region between the surface bus electrode 112B and the lead wire 20. As a result, the solar cell 210 secures a long connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction, so that the light receiving surface bus electrode 212B and the lead wire in the first direction are long. It is possible to increase the bonding strength with 20 and suppress the peeling of the lead wire 20.

On the other hand, the back surface connection electrode 213B, which is a silver paste electrode formed by applying and firing a silver paste using an electrode material containing silver, is more in a state after the firing treatment than the light receiving surface electrode 212, which is a silver paste electrode. , It is said that it has a large amount of glass components. Most of the silver paste electrode is composed of silver and glass after the firing treatment. In the silver paste electrode, silver has a function of passing an electric current. In the silver paste electrode, the glass has a function of maintaining the bonding strength between the semiconductor substrate 11 and the electrode.

Comparing the light receiving surface electrode 212 which is a silver paste electrode and the back surface connecting electrode 213B which is a silver paste electrode, the light receiving surface electrode 212 has a silver ratio in the electrode material of the back surface connecting electrode 213B in order to reduce the resistance at the electrode. Is made higher than. In the light receiving surface electrode 212, it is preferable to increase the ratio of silver in the electrode material as much as possible in order to reduce the resistance at the electrode. On the other hand, on the back surface side of the solar cell 210, the back surface current collecting electrode 13A using the electrode material containing aluminum is responsible for the function of collecting current from the semiconductor substrate 11. Therefore, in the back surface connection electrode 213B, the bonding strength with the semiconductor substrate 11 can be increased by lowering the ratio of silver in the electrode material and increasing the ratio of the glass component in the electrode material.

Therefore, in the solar cell 210, the ratio of the glass component in the electrode material in the back surface connection electrode 213B in the state after the firing treatment is larger than the ratio of the glass component in the electrode material in the light receiving surface electrode 212 in the state after the firing treatment. By increasing the value, it is possible to maintain the bonding strength between the semiconductor substrate 11 and the back surface connection electrode 213B at a high level at which the back surface connection electrode 213B does not peel off. As a result, the solar cell 210 makes the total length of the back surface connection electrodes 213B in the first direction shorter than the total length of the first region of the light receiving surface bus electrode 212B in the first direction. However, it is possible to maintain the bonding strength between the semiconductor substrate 11 and the back surface connection electrode 213B at a high level at which the back surface connection electrode 213B does not peel off.

As described above, in the solar cell 210 according to the third embodiment, the first region 61 of the light receiving surface bus electrode 212B and the back surface connection electrode 213B are arranged at corresponding positions in the plane of the semiconductor substrate 11. ing. As a result, the solar cell 210 can reduce the damage rate of the solar cell 210 due to the warp of the solar cell 210 at the time of manufacturing the solar cell module, similarly to the above-mentioned solar cell 10 and the solar cell 110. It is possible.

Further, in the solar cell 210 according to the third embodiment, the other end 102 side of the solar cell 210, which is the end portion on the back surface side of the solar cell 210 on the interconnection side, is from the end surface of the solar cell 210. Increase the distance to the backside connection electrode 213B. As a result, the stress concentration of the lead wire 20 on the bent portion 20a can be reduced as in the case of the solar cell 110 according to the second embodiment, and the light receiving surface glass and the lead wire 20 serving as the light receiving surface protection portion 31 Due to the difference in the coefficient of linear expansion of the above, the repetitive stress applied to the bent portion 20a due to the day and night temperature cycle can be reduced, so that a solar cell module having excellent long-term reliability can be realized.

Further, in the solar cell 210 according to the third embodiment, the length of the connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction is the length of the back surface connection electrode 213B and the lead in the first direction. It is longer than the length of the connection area with the wire 20. As a result, the solar cell 210 secures a long connection region between the light receiving surface bus electrode 212B and the lead wire 20 in the first direction, so that the light receiving surface bus electrode 212B and the lead wire in the first direction are long. It is possible to increase the bonding strength with 20 and suppress the peeling of the lead wire 20.

The configuration shown in the above-described embodiment shows an example of the contents of the present invention, and the techniques of the embodiments can be combined with each other, or can be combined with another known technique. It is also possible to omit or change a part of the configuration without departing from the gist of the present invention.

1,11 Semiconductor substrate, 2n type impurity diffusion layer, 3 Antireflection film, 4 BSF layer, 10,110,210 Solar cell, 11A light receiving surface, 11B back surface, 12,112,212 light receiving surface electrode, 12B, 112B , 212B light receiving surface bus electrode, 12Ba light receiving surface bus electrode side surface, 12G light receiving surface grid electrode, 12a, 13b silver electrode paste, 13,113,213 backside electrode, 13A backside current collecting electrode, 13B, 113B, 213B, 1131, 1123, 1133, 1134, 1135, 1136, 1137, 1138 Backside connection electrode, 13a aluminum electrode paste, 20 lead wire, 20a bend, 20b width side of lead wire, 25 horizontal lead wire, 26 output lead wire, 31 Light receiving surface protection part, 32 back surface protection part, 33 light receiving surface side sealing material, 34 back surface side sealing material, 40 frame, 50 solar cell string, 60 through hole, 61,611,612,613,614,615,616 , 617, 618 1st region, 62 2nd region, 63 connection part, 63a connection part outer side surface, 70 solar cell array, 100 solar cell module, 101 one end, 102 other end, A1, A2, A3, A4 A5, A6, A7, A8 First region length, B1, B2, B3, B4, B5, B6, B7, B8, B9 Distance, C1, C2, C3, C4, C5, C6, C7, C8 Backside connection electrode Length, D1, D2, D3, D4, D5, D6, D7, D8, D9 distance.

Claims (8)

A semiconductor substrate with a pn junction and
A light receiving surface bus electrode extending in the first direction on the light receiving surface side of the semiconductor substrate and a light receiving surface bus electrode provided parallel to the second direction intersecting the light receiving surface bus electrode and connected to the light receiving surface bus electrode. A light-receiving surface electrode having a plurality of light-receiving surface grid electrodes,
A plurality of back surface connecting electrodes dispersed and arranged along the first direction on the back surface side of the semiconductor substrate facing the side opposite to the light receiving surface, and the entire region of the back surface other than the back surface connecting electrodes. A back surface electrode having a back surface current collector electrode provided and connected to the plurality of back surface connection electrodes,
With
The light receiving surface bus electrode is provided with a plurality of through holes penetrating in the thickness direction of the light receiving surface bus electrode along the first direction.
The back surface connection electrode is arranged at a position facing the region of the light receiving surface bus electrode excluding the plurality of through holes in the thickness direction of the semiconductor substrate .
The light receiving surface bus electrode is
In the first direction, a plurality of first regions in which the through holes are not provided, and
In the first direction, the plurality of second regions provided with the through holes and
With
The back surface connection electrodes are arranged at positions opposite to the plurality of first regions in the thickness direction of the semiconductor substrate.
In the first direction, the first region of the light receiving surface bus electrode is longer than the back surface connecting electrode arranged at positions facing each other in the thickness direction of the semiconductor substrate.
In the first direction, the sum of the lengths of the plurality of first regions of the light receiving surface bus electrode is longer than the sum of the lengths of the plurality of back surface connecting electrodes.
The light receiving surface electrode and the back surface connecting electrode are paste electrodes containing silver and glass.
The light receiving surface electrode has a higher ratio of silver in the electrode material than the back surface connecting electrode.
The back surface connection electrode has a higher ratio of glass in the electrode material than the light receiving surface electrode.
A solar cell characterized by. The light receiving surface bus electrode has a linear shape in which both ends in the second direction orthogonal to the first direction in the plane of the semiconductor substrate are parallel to the first direction.
The solar cell according to claim 1. Both ends of the light receiving surface bus electrode in the first direction are formed by the first region.
The solar cell according to claim 1 or 2 . The distance between the first regions adjacent to each other on the end side in the first direction is shorter than the distance between the first regions adjacent to each other on the inner side in the first direction.
The solar cell according to any one of claims 1 to 3 . The semiconductor substrate has a first end edge portion that is an end portion of the solar cell in the first direction and an end portion of the solar cell that is opposite to the first end edge portion in the first direction. Has a rectangular shape with a second edge that is
The distance between the back surface connection electrode adjacent to the second end edge portion and the second end edge portion is larger than the distance between the back surface connection electrode adjacent to the first end edge portion and the first end edge portion. For a long time,
The solar cell according to any one of claims 1 to 4 . The plurality of solar cells according to any one of claims 1 to 5 ,
In the two solar cells adjacent to each other in the first direction, a lead wire connecting the light receiving surface bus electrode of one solar cell and the back surface connecting electrode of the other solar cell.
A solar cell module characterized by being equipped with. The two according to claim 5 , wherein the second end edge portion of one solar cell and the first end edge portion of the other solar cell are arranged so as to face each other and are adjacent to each other in the first direction. With solar cells
A lead wire connecting the back surface connection electrode of the one solar cell and the light receiving surface bus electrode of the other solar cell.
With
The lead wire connects the back surface connection electrode on the second end side of the one solar cell and the light receiving surface bus electrode on the first end side of the other solar cell. To do,
A solar cell module featuring. The width of the light receiving surface bus electrode is equal to the width of the lead wire,
The lead wires are located on both sides of the light receiving surface bus electrode in a second direction orthogonal to the first direction in the plane of the semiconductor substrate, and on both sides of the lead wire in the second direction. The position of the side surface and the position are the same, and the light receiving surface bus electrode is overlapped and connected.
The solar cell module according to claim 6 or 7 .