JP4040662B1 - Solar cell, solar cell string and solar cell module - Google Patents

Abstract

[PROBLEMS] To reduce the occurrence of cracking of a solar cell at an interface portion between a connecting portion and a non-connecting portion of an interconnector on a light receiving surface of a solar cell when the solar cell is warped in a cooling process after the interconnector is connected Provide solar cells, solar cell strings and solar cell modules.
A bus bar electrode and a plurality of linear finger electrodes extending from the bus bar electrode are provided on a first main surface of a semiconductor substrate, and the bus bar electrode is connected to an interconnector. Including a connection portion and a first non-connection portion not connected to the interconnector, wherein the first connection portion and the first non-connection portion are alternately arranged, and the surface shape of the first non-connection portion is , A solar cell having a shape in which the tip portion on the first connection portion side has an arc shape, a solar cell string including the solar cell, and a solar cell module.
[Selection] Figure 1

Description

  The present invention relates to a solar cell, a solar cell string, and a solar cell module.

  In recent years, a solar cell that directly converts solar energy into electric energy has been rapidly expected as a next-generation energy source particularly from the viewpoint of global environmental problems. There are various types of solar cells, such as those using compound semiconductors or organic materials, but the mainstream is currently using silicon crystals.

  FIG. 14 shows a schematic cross-sectional view of an example of a conventional solar cell. Here, in the solar cell, the n + layer 11 is formed on the light receiving surface of the p-type silicon substrate 10, thereby forming a pn junction between the p-type silicon substrate 10 and the n + layer 11. An antireflection film 12 and a silver electrode 13 are respectively formed on the light receiving surface of the silicon substrate 10. A p + layer 15 is formed on the back surface of the p-type silicon substrate 10 opposite to the light receiving surface. An aluminum electrode 14 and a silver electrode 16 are formed on the back surface of the p-type silicon substrate 10, respectively.

  An example of the conventional manufacturing method of a solar cell is shown to Fig.15 (a)-(i). First, as shown in FIG. 15A, a silicon ingot 17 obtained by recrystallizing a p-type silicon crystal raw material after melting in a crucible is cut into silicon blocks 18. Next, as shown in FIG. 15B, the p-type silicon substrate 10 is obtained by cutting the silicon block 18 with a wire saw.

  Next, the damage layer 19 at the time of slicing the p-type silicon substrate 10 shown in FIG. 15C is removed by etching the surface of the p-type silicon substrate 10 with alkali or acid. At this time, if the etching conditions are adjusted, minute irregularities (not shown) can be formed on the surface of the p-type silicon substrate 10. Due to the unevenness, reflection of sunlight incident on the surface of the p-type silicon substrate 10 is reduced, and the conversion efficiency of the solar cell can be increased.

Subsequently, as shown in FIG. 15 (d), a dopant liquid 20 containing a compound containing phosphorus is applied on one main surface (hereinafter referred to as “first main surface”) of the p-type silicon substrate 10. Then, the p-type silicon substrate 10 after the application of the dopant liquid 20 is heat-treated at a temperature of 800 ° C. to 950 ° C. for 5 to 30 minutes, whereby phosphorus as an n-type dopant diffuses into the first main surface of the p-type silicon substrate 10 Then, as shown in FIG. 15E, the n + layer 11 is formed on the first main surface of the p-type silicon substrate 10. As a method for forming the n + layer 11, there is a method by vapor phase diffusion using P ₂ O ₅ or POCl ₃ besides the method of applying the dopant liquid.

  Next, after the glass layer formed on the first main surface of the p-type silicon substrate 10 during phosphorus diffusion is removed by acid treatment, the first main surface of the p-type silicon substrate 10 as shown in FIG. An antireflection film 12 is formed thereon. Known methods for forming the antireflection film 12 include a method of forming a titanium oxide film using an atmospheric pressure CVD method and a method of forming a silicon nitride film using a plasma CVD method. In addition, when phosphorus is diffused by a method of applying a dopant solution, the n + layer 11 and the antireflection coating 12 are simultaneously formed by using a dopant solution that contains the material of the antireflection coating 12 in addition to phosphorus. It can also be formed. The antireflection film 12 may be formed after the silver electrode is formed.

  Then, as shown in FIG. 15G, an aluminum electrode 14 is formed on the other main surface (hereinafter referred to as “second main surface”) of the p-type silicon substrate 10 and the second of the p-type silicon substrate 10. A p + layer 15 is formed on the main surface. The aluminum electrode 14 and the p + layer 15 are formed by, for example, printing aluminum paste made of aluminum powder, glass frit, resin and organic solvent by screen printing or the like, and then heat-treating the p-type silicon substrate 10 to melt the aluminum. A p + layer 15 is formed under the aluminum-silicon alloy layer formed by alloying with silicon, and an aluminum electrode 14 is formed on the second main surface of the p-type silicon substrate 10. Further, the difference in dopant concentration between the p-type silicon substrate 10 and the p + layer 15 causes a potential difference (acts as a potential barrier) at the interface between the p-type silicon substrate 10 and the p + layer 15, and the photogenerated carriers are converted into p-type silicon The recombination in the vicinity of the second main surface of the substrate 10 is prevented. This improves both the short circuit current (Isc) and the open circuit voltage (Voc) of the solar cell.

  Thereafter, as shown in FIG. 15H, the silver electrode 16 is formed on the second main surface of the p-type silicon substrate 10. The silver electrode 16 can be obtained, for example, by heat-treating the p-type silicon substrate 10 after printing a silver paste made of silver powder, glass frit, resin and organic solvent by screen printing or the like.

  Then, as shown in FIG. 15 (i), a silver electrode 13 is formed on the first main surface of the p-type silicon substrate 10. The silver electrode 13 is a line of the silver electrode 13 in order to keep the series resistance including the contact resistance with the p-type silicon substrate 10 low and to reduce the formation area of the silver electrode 13 so as not to reduce the amount of incident sunlight. Pattern design such as width, pitch and thickness is important. As a method for forming the silver electrode 13, for example, a silver paste made of silver powder, glass frit, resin and organic solvent is printed on the surface of the antireflection film 12 by screen printing or the like, and then the p-type silicon substrate 10 is heat-treated. As a result, a fire-through method in which silver paste penetrates the antireflection film 12 and allows good electrical contact with the first main surface of the p-type silicon substrate 10 is used in the mass production line.

  As described above, the solar cell having the configuration shown in FIG. 14 can be manufactured. The surface of the silver electrode 13 and the silver electrode 16 can be coated with solder by immersing the p-type silicon substrate 10 after the formation of the silver electrode 13 and the silver electrode 16 in a molten solder bath. This solder coating may be omitted depending on the process. Further, the solar cell manufactured as described above can be irradiated with simulated sunlight using a solar simulator, and the current-voltage (IV) characteristic of the solar cell can be measured to inspect the IV characteristic.

  In many cases, a plurality of solar cells are connected in series to form a solar cell string, and then the solar cell string is sealed with a sealing material and sold and used as a solar cell module.

  16A to 16E show an example of a conventional method for manufacturing a solar cell module. First, as shown in FIG. 16A, an interconnector 31 that is a conductive member is connected to the silver electrode on the first main surface of the solar cell 30.

  Next, as shown in FIG. 16B, the solar cells 30 to which the interconnectors 31 are connected are arranged in a row, and the interconnectors 31 other than the interconnectors 31 that are connected to the silver electrodes on the first main surface of the solar cells 30. The end is connected to the silver electrode on the second main surface of the other solar cell 30 to produce the solar cell string 34.

  Next, as shown in FIG. 16C, the solar cell strings are arranged side by side, and the interconnector 31 protruding from both ends of the solar cell string and the interconnector 31 protruding from both ends of the other solar cell string are electrically conductive. The solar cell strings are connected to each other by connecting in series using the wiring member 33 as a member.

  Subsequently, as shown in FIG. 16 (d), the connected solar cell string 34 is sandwiched between EVA (ethylene vinyl acetate) films 36 as a sealing material, and then between a glass plate 35 and a back film 37. Pinch. Then, when the bubbles that have entered between the EVA films 36 are decompressed and heated, the EVA film 36 is cured and the solar cell string is sealed in the EVA. Thereby, a solar cell module is produced.

  Then, as shown in FIG.16 (e), a solar cell module is arrange | positioned in the aluminum frame 40, and the terminal box 38 provided with the cable 39 is attached to a solar cell module. The solar cell module manufactured as described above is irradiated with simulated sunlight using a solar simulator, and the current-voltage (IV) characteristics of the solar cell are measured to inspect the IV characteristics.

  The schematic plan view of FIG. 17 shows a pattern of the silver electrode 13 formed on the first main surface of the p-type silicon substrate 10 which becomes the light receiving surface of the solar cell shown in FIG. Here, the silver electrode 13 is composed of one linear bus bar electrode 13a having a relatively large width and a plurality of relatively small linear finger electrodes 13b extending from the bus bar electrode 13a.

  The schematic plan view of FIG. 18 shows a pattern of the aluminum electrode 14 and the silver electrode 16 formed on the second main surface of the p-type silicon substrate 10 which is the back surface of the solar cell shown in FIG. Here, the aluminum electrode 14 is formed on substantially the entire second main surface of the p-type silicon substrate 10, and the silver electrode 16 is formed only on a part of the second main surface of the p-type silicon substrate 10. This is because it is difficult to coat the aluminum electrode 14 with solder, and thus a silver electrode 16 that can be coated with solder may be required.

FIG. 19 shows a schematic cross-sectional view of a solar cell string in which the solar cells having the configuration shown in FIG. 14 are connected in series. Here, the interconnector 31 fixed to the bus bar electrode 13a on the light receiving surface of the solar cell with solder or the like is fixed to the silver electrode 16 on the back surface of another adjacent solar cell with solder or the like. In FIG. 19, the description of the n + layer and the p + layer is omitted.
JP 2005-142282 A

As solar power generation systems rapidly spread, it is essential to reduce the manufacturing cost of solar cells. In reducing the manufacturing cost of solar cells, increasing the size and reducing the thickness of a silicon substrate, which is a semiconductor substrate, is a very effective means. However, with the increase in size and thickness of silicon substrates, when a solar cell string is formed, cooling after a heating process in which the bus bar electrode on the light-receiving surface of the solar cell and the interconnector made of copper are fixed and connected by solder or the like In the process, the difference in thermal expansion coefficient between the silicon substrate of the solar cell and the interconnector (the thermal expansion coefficient of silicon is 3.5 × 10 ⁻⁶ / K, whereas copper is 17.6 × 10 ⁻⁶ / K, 5 times Because the interconnector contracts more than the solar cell, the solar cell is warped, and further, the light receiving surface of the solar cell that is in contact with the bus bar electrode of the solar cell is cracked. There was a thing.

  Therefore, Patent Document 1 discloses a method of providing a small cross-sectional area part whose cross-sectional area is locally reduced in an interconnector that connects adjacent solar cells. As described above, when the interconnector and solar cell that have been heated by the heating step are cooled to room temperature, a concave warp occurs in the solar cell. At that time, a force (restoring force) for returning to the original shape is generated in the solar cell, and this restoring force applies tensile stress to the interconnector. According to the method disclosed in Patent Literature 1, when a tensile stress is applied to the interconnector, a small cross-sectional area that is relatively weak compared to other portions is stretched to reduce the warpage of the solar cell. However, further improvements were desired.

  Therefore, by using the interconnector described in Patent Literature 1 to connect the solar cells having the light receiving surface electrode having the shape shown in FIG. 20 and the back surface electrode having the shape shown in FIG. 21 to form a solar cell string, It is considered to reduce the warpage of the solar cell. FIG. 22 shows a schematic cross-sectional view of an example of the solar cell string, and FIG. 23 shows a schematic enlarged plan view of the light receiving surface of the solar cell string shown in FIG.

  Here, as shown in FIG. 20, the silver electrode 13 on the light-receiving surface that is the first main surface of the p-type silicon substrate 10 of the solar cell is composed of one linear bus bar electrode 13a and bus bar electrode having a relatively large width. A plurality of linear finger electrodes 13b extending from 13a and having a relatively small width. The bus bar electrode 13a includes a linear first connection part 51 for fixing and connecting to the interconnector, and a first non-connection part 42 which is a gap that is not connected to the interconnector. The first connection part 51 and the 1st non-connecting part 42 are arranged by turns along the longitudinal direction of bus bar electrode 13a. Here, the surface shapes of the first connecting portion 51 and the first non-connecting portion 42 are each rectangular.

  As shown in FIG. 21, the aluminum electrode 14 is formed on almost the entire second main surface of the p-type silicon substrate 10, and the silver electrode 16 is only a part of the second main surface of the p-type silicon substrate 10. Is formed. Here, the silver electrode 16 becomes a second connection part for fixing and connecting to the interconnector, and the aluminum electrode 14 positioned between the silver electrodes 16 becomes a second non-connecting part 14a not connected to the interconnector. In addition, the 2nd main surface of the p-type silicon substrate 10 as a semiconductor substrate turns into a main surface on the opposite side to the 1st main surface of the p-type silicon substrate 10 as a semiconductor substrate.

  Further, as shown in FIG. 22, in the solar cell string using the interconnector described in Patent Document 1, the interconnector 31 is fixedly connected to the first connection portion 51 of the light receiving surface of the solar cell by solder or the like. However, it is fixed and connected to the silver electrode 16 on the back surface of another adjacent solar cell with solder or the like. In FIG. 22, the description of the n + layer, the p + layer, and the antireflection film is omitted.

  As shown in FIGS. 22 and 23, the small cross-sectional area 41 of the interconnector 31 is disposed in the first non-connected portion 42 and the second non-connected portion 14a of the solar cell, respectively. The small cross-sectional area 41 is not fixed with solder or the like. Accordingly, when a tensile stress is applied to the interconnector 31, the small cross-sectional area 41 having a relatively low strength as compared with other portions can be freely extended, so that the warpage of the solar cell can be reduced. it can.

  However, in this solar cell string, when the solar cell is warped in the cooling step after the interconnector is connected, the first connection portion of the light receiving surface of the solar cell constituting the solar cell string is caused by the warp. Since the solar cell sometimes cracked at the interface between 51 and the first non-connecting portion 42, the improvement was desired.

  In view of the above circumstances, the object of the present invention is to provide an interface portion between the connection portion and the non-connection portion of the interconnector on the light receiving surface of the solar cell when the solar cell is warped in the cooling step after the interconnector is connected. An object of the present invention is to provide a solar cell, a solar cell string, and a solar cell module that can reduce the occurrence of cracks in the solar cell.

In the present invention, a bus bar electrode and a plurality of linear finger electrodes extending from the bus bar electrode are provided on the first main surface of the semiconductor substrate, and the bus bar electrode is connected to the interconnector. Including a connection portion and a first non-connection portion that is a gap that is not connected to the interconnector, wherein the first connection portion and the first non-connection portion are alternately arranged. The surface shape is a solar cell having a shape in which the front end portion on the first connection portion side has an arc shape. In the present invention, a bus bar electrode and a plurality of linear finger electrodes extending from the bus bar electrode are provided on the first main surface of the semiconductor substrate, and the bus bar electrode is connected to the interconnector. Including a first connection portion and a first non-connection portion that is an opening that is not connected to the interconnector, wherein the first connection portion and the first non-connection portion are alternately arranged to form a first non-connection. The surface shape of the part is a solar cell in which the tip part on the first connection part side is an arc shape. In addition, the solar cell of the present invention may include a detour portion that electrically connects the first connection portions arranged on both sides of the first non-connection portion, bypassing the first non-connection portion. .

  Here, in the solar cell of the present invention, the surface shape of the first non-connection portion can be a circle, an ellipse, or a track.

  Moreover, in the solar cell of this invention, the 2nd connection part for connecting to an interconnector on the 2nd main surface on the opposite side to the 1st main surface of a semiconductor substrate, and the 2nd non-connection which is not connected to an interconnector Can be formed alternately.

Moreover, in the solar cell of this invention, the length of the 1st non-connection part in the arrangement direction of a 1st connection part and a 1st non-connection part is 2nd which faces the 1st non-connection part on both sides of a semiconductor substrate. It is preferable that the length of the non-connecting portion in the arrangement direction between the second connecting portion and the second non-connecting portion is shorter.
Moreover, the solar cell of this invention may contain the part in which the 2nd non-connecting part is not formed in the position which faces a 1st non-connecting part and a semiconductor substrate.

  Further, the present invention is a solar cell string in which a plurality of the above solar cells are connected, and in the solar cells adjacent to each other, the first connection portion of the first solar cell and the second connection portion of the second solar cell. Are solar cell strings connected to the same interconnector.

  Here, in the solar cell string of the present invention, the cross-sectional area of the interconnector is locally reduced in at least one of the location corresponding to the first non-connecting portion and the location corresponding to the second non-connecting portion. It is preferable that the small cross-sectional area part arranged is arranged.

  Furthermore, the present invention is a solar cell module in which the solar cell string is sealed with a sealing material.

  According to the present invention, the occurrence of cracking of the solar cell at the interface portion between the interconnector connecting portion and the non-connecting portion on the light receiving surface of the solar cell when the solar cell is warped in the cooling step after the interconnector is connected. Solar cells, solar cell strings, and solar cell modules that can be reduced can be provided.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

  FIG. 1 shows a schematic plan view of a light receiving surface as a first main surface of an example of the solar cell of the present invention. In this solar cell, p-type single crystal silicon is used as a material of the p-type silicon substrate 10, and the first main surface of the p-type silicon substrate 10 that serves as a light-receiving surface of the solar cell extends in the vertical direction of the paper surface. A relatively wide linear bus bar electrode 13a and a plurality of narrow linear finger electrodes 13b extending from the bus bar electrode 13a in the left-right direction on the paper surface are provided. In addition, the bus bar electrode 13a is formed by alternately arranging first connection portions 51 for fixing and connecting to the interconnector and first non-connection portions 42 that are gaps not connected to the interconnector.

  FIG. 2 shows a schematic plan view of the back surface as the second main surface of the solar cell shown in FIG. In the 2nd main surface of p type silicon substrate 10 used as the back of the solar cell of the present invention, silver electrode 16 as the 2nd connection part for connecting to an interconnector, and the 2nd non-connection part which is not connected to an interconnector 14a are alternately formed. Here, the 2nd non-connecting part 14a consists of the aluminum electrode 14 between the silver electrodes 16 adjacent to the longitudinal direction of the silver electrode 16 as a 2nd connecting part.

  In this solar cell, as shown in FIG. 1, the surface shape of the first non-connection portion 42 is a track shape in which the tip portion on the first connection portion 51 side is arc-shaped (having arc-shaped portions at both ends). However, the arc-shaped portion is characterized in that the shape is formed by two straight lines. As a result of intensive studies by the inventor, the interface portion between the first connection portion 51 and the first non-connection portion 42 is formed in an arc shape, so that in the cooling step after the interconnector connection at the time of manufacturing the solar cell string When warpage occurs in the solar cell, the occurrence of cracking of the solar cell at the interface portion between the first connection portion 51 and the first non-connection portion 42 on the light receiving surface of the solar cell is reduced due to the warpage. This is because we have found what we can do. Although the reason is not certain, the first connection of the solar cell is caused when the solar cell is warped in the cooling step after the connection of the interconnector by forming the tip of the surface shape of the first non-connecting portion 42 in an arc shape. It is presumed that the stress received by the interface portion between the portion 51 and the first non-connecting portion 42 is dispersed.

  FIG. 3 shows a schematic cross section taken along the line III-III in FIGS. 1 and 2. For example, as shown in FIGS. 1 to 3, in the present invention, the length of the first non-connection portion 42 in the arrangement direction of the first connection portion 51 and the first non-connection portion 42 (up and down direction in the drawing of FIG. 1). The length L2 of the second non-connecting portion 14a facing the first non-connecting portion 42 is a length L2 in the arrangement direction of the second connecting portion and the second non-connecting portion 14a (vertical direction in the drawing of FIG. 2). Is also preferably short. As a result of intensive studies by the present inventor, the length L1 of the first non-connection portion 42 is the length of the second non-connection portion 14a facing the first non-connection portion 42 with the p-type silicon substrate 10 interposed therebetween. It has been found that the occurrence of cracks at the interface between the first connecting portion 51 and the first non-connecting portion 42 of the light receiving surface of the solar cell constituting the solar cell string can be further reduced by making the length shorter than the length L2. It is because. This is because the aluminum constituting the second non-connecting portion 14a longer than the first non-connecting portion 42 has a reinforcing effect, so that the solar cell receives light when the solar cell is warped in the cooling step after the interconnector is connected. It is considered that the occurrence of cracking of the solar cell at the interface portion between the first connecting portion 51 and the first non-connecting portion 42 can be further reduced.

  In order to obtain the above effect, at least one pair of the first non-connecting portion 42 and the second non-connecting portion 14a face each other across the p-type silicon substrate 10, and the first non-connecting portions facing each other. In at least one set of the part 42 and the second non-connection part 14a, the length L1 of the first non-connection part 42 only needs to be shorter than the length L2 of the second non-connection part 14a.

  FIG. 4 shows a schematic plan view of a light receiving surface as a first main surface of another example of the solar cell of the present invention, and FIG. 5 schematically shows a back surface as a second main surface of the solar cell shown in FIG. A plan view is shown. FIG. 6 shows a schematic cross section along VI-VI in FIGS. 4 and 5. This solar cell is characterized in that p-type polycrystalline silicon is used as the material of the p-type silicon substrate 10. Other explanations are the same as above.

  In FIG. 7, the typical top view of an example of the interconnector used for the solar cell string of this invention is shown. Here, the interconnector 31 has a plurality of small cross-sectional area portions 41 in which the cross-sectional area of the cross section perpendicular to the longitudinal direction of the interconnector 31 is locally small. In the present invention, the “small cross-sectional area portion” refers to a portion of the interconnector in which the area of the cross section perpendicular to the longitudinal direction of the interconnector is locally reduced. In the present invention, the shape and material of the interconnector are not particularly limited as long as it is a conductive member.

  Moreover, in each of FIGS. 8-10, the typical top view of the other example of the interconnector used for this invention is shown. Each of these interconnectors 31 also has a small cross-sectional area 41 in which the cross-sectional area of the interconnector 31 is locally reduced.

  FIG. 11 shows a schematic cross-sectional view of an example of the solar cell string of the present invention in which the solar cells having the light receiving surface shown in FIG. 1 and the back surface shown in FIG. 2 are connected in series, and FIG. 12 and FIG. The typical enlarged plan view when a solar cell string is seen from the light-receiving surface side is shown.

  Here, one end of the interconnector 31 made of one conductive member is fixedly connected to the first connection part 51 of the first solar cell 80, and the other end of the interconnector 31 is connected to the second solar cell. It is fixedly connected to the silver electrode 16 as the second connection portion of the battery 81. In the interconnector 31, the small cross-sectional area 41 of the interconnector 31 is connected to the first unconnected portion 42 a on the light receiving surface of the first solar cell 80 and the second unconnected portion 14 a on the back surface of the second solar cell 81. The first non-connected portion 42 and the second non-connected portion 14a of the solar cell are not fixed to the interconnector 31 and are not connected. The interconnector 31 is bent at the end of the solar cell. Further, in FIG. 11, the description of the antireflection film is omitted.

  In the solar cell string of the present invention, since the tip portion of the surface shape of the first non-connection portion 42 of the solar cell has an arc shape, as described above, the tip portion of the surface shape of the first non-connection portion 42. Compared with the case where the arc is not arcuate, the interface portion between the first connection portion 51 and the first non-connection portion 42 of the light receiving surface of the solar cell when the solar cell is warped in the cooling step after the interconnector is connected The occurrence of cracks in the solar cell in can be reduced.

  In the solar cell string of the present invention having such a configuration, the first non-connection portion 42 and the second non-connection portion 14a of the solar cell are not connected to the interconnector 31, respectively. The connection length with the silver electrode 16 which is the 1st connection part 51 and the 2nd connection part can be reduced. Thus, when the connection length of the interconnector 31 and the 1st connection part 51 of a solar cell and the silver electrode 16 which is a 2nd connection part is reduced, the p-type silicon substrate which comprises the interconnector 31 and a solar cell Since the stress generated by the difference in thermal expansion coefficient with respect to 10 can be reduced, the first connection portion 51 and the first non-contact of the light receiving surface of the solar cell due to the warp generated in the solar cell in the cooling step after the interconnector connection. It is possible to further reduce the occurrence of cracks in the solar cell at the interface portion with the connection portion 42.

  Further, the small cross-sectional area 41 of the interconnector 31 is arranged at least one place, preferably all places, corresponding to the first non-connecting portion 42 and corresponding to the second non-connecting portion 14a. By connecting the connector 31, in addition to the stress reduction effect described above, the small cross-sectional area portion 41 having a relatively low strength compared to other portions of the interconnector 31 extends to further reduce the stress. It will be. That is, when the small cross-sectional area 41 of the interconnector 31 is disposed in each of the first non-connecting portion 42 and the second non-connecting portion 14a, the small cross-sectional area 41 is in a free state that is not fixed. Therefore, it can be freely deformed and the stress relaxation effect by stretching can be sufficiently exhibited. Therefore, in this case, cracking of the solar cell at the interface portion between the first connecting portion 51 and the first non-connecting portion 42 of the light receiving surface of the solar cell due to warpage occurring in the solar cell in the cooling step after the interconnector is connected. Can be greatly reduced.

  In the above, the solar cell string is formed using the interconnector shown in FIG. 7, but as shown in the schematic plan view of FIG. 13 in which the small cross-sectional areas 41 are formed at equal intervals. A solar cell string can also be formed using a simple interconnector 31. In the case where the solar cell string is formed using such an interconnector in which the intervals between the adjacent small cross-sectional area portions 41 are equal, the formation of the small cross-sectional area portion 41 becomes easier. The manufacturing cost is reduced, and the productivity of the solar cell string can be improved.

  Moreover, the solar cell module of the present invention can be manufactured by sealing the solar cell string of the present invention as described above with a sealing material such as EVA by a conventionally known method.

  The description other than the above is the same as the description in the background art section above, but is not limited to the description. For example, in the present invention, a semiconductor substrate made of a material other than single crystal silicon and polycrystalline silicon may be used, and the p-type and n-type conductivity types described in the background art section may be interchanged. In the present invention, the first connection portion and the second connection portion are not necessarily silver electrodes.

  Further, in the above description, the case where the surface shape of the first non-connection portion is a track shape has been described. However, in the present invention, the surface shape of the first non-connection portion is that the tip portion on the side in contact with the first connection portion is The shape is not particularly limited as long as it is arcuate. However, from the viewpoint of further reducing the occurrence of cracks in the solar cell at the interface portion between the first connection portion and the first non-connection portion of the light-receiving surface of the solar cell constituting the solar cell string, the surface of the first non-connection portion The shape is preferably a circular shape, an elliptical shape, or a track shape in which a tip portion on the side in contact with the first connecting portion is an arc shape.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the present invention, the occurrence of cracking of the solar cell at the interface portion between the interconnector connecting portion and the non-connecting portion on the light receiving surface of the solar cell when the solar cell is warped in the cooling step after the interconnector is connected. Solar cells, solar cell strings, and solar cell modules that can be reduced can be provided.

It is a typical top view of the light-receiving surface as a 1st main surface of an example of the solar cell of this invention. It is a typical top view of the back surface as a 2nd main surface of the solar cell shown in FIG. FIG. 3 is a schematic cross-sectional view taken along the line III-III in FIGS. 1 and 2. It is a typical top view of the light-receiving surface as the 1st main surface of other examples of the solar cell of this invention. It is a schematic plan view of the back surface as a 2nd main surface of the solar cell shown in FIG. FIG. 6 is a schematic cross-sectional view taken along VI-VI in FIGS. 4 and 5. It is a typical top view of an example of the interconnector used for the solar cell string of the present invention. It is a typical top view of other examples of an interconnector used for the solar cell string of the present invention. It is a typical top view of other examples of an interconnector used for the solar cell string of the present invention. It is a typical top view of other examples of an interconnector used for the solar cell string of the present invention. It is typical sectional drawing of an example of the solar cell string of this invention which connected the solar cell which has the light-receiving surface shown in FIG. 1, and the back surface shown in FIG. 2 in series. It is a typical enlarged plan view when the solar cell string shown in FIG. 11 is seen from the light receiving surface side. It is a typical top view of other examples of an interconnector used for the solar cell string of the present invention. It is typical sectional drawing of an example of the conventional solar cell. It is a schematic diagram which shows an example of the manufacturing method of the conventional solar cell. It is a schematic diagram which shows an example of the manufacturing method of the conventional solar cell module. FIG. 15 is a schematic plan view showing a pattern of silver electrodes formed on a first main surface of a p-type silicon substrate that serves as a light receiving surface of the solar cell shown in FIG. 14. It is a typical top view which shows the pattern of the aluminum electrode and silver electrode which were formed on the 2nd main surface of the p-type silicon substrate used as the back surface of the solar cell shown in FIG. It is typical sectional drawing of the solar cell string which connected the solar cell shown in FIG. 14 in series. It is a typical top view which shows an example of the pattern of the electrode of the light-receiving surface of a solar cell. It is a typical top view which shows an example of the pattern of the electrode of the back surface of a solar cell. 20 is a schematic cross-sectional view of an example of a solar cell string in which solar cells having electrodes on the light receiving surface having the shape shown in FIG. 20 and electrodes on the back surface of the pattern shown in FIG. 21 are connected using the interconnector described in Patent Document 1. FIG. is there. It is a typical enlarged plan view of the light-receiving surface of the solar cell string shown in FIG.

Explanation of symbols

  10 p-type silicon substrate, 11 n + layer, 12 antireflection film, 13, 16 silver electrode, 13a bus bar electrode, 13b finger electrode, 14 aluminum electrode, 14a second unconnected portion, 15 p + layer, 17 silicon ingot, 18 silicon block, 19 damage layer, 20 dopant liquid, 30 solar cell, 31 interconnector, 33 wiring material, 34 solar cell string, 35 glass plate, 36 EVA film, 37 back film, 38 terminal box, 39 cable, 40 aluminum Frame, 41 Small cross-sectional area part, 42 1st non-connection part, 51 1st connection part, 80 1st solar cell, 81 2nd solar cell.

Claims (10)

A bus bar electrode and a plurality of linear finger electrodes extending from the bus bar electrode are provided on the first main surface of the semiconductor substrate,
The bus bar electrode includes a first connection portion for connecting to the interconnector , and a first non-connection portion that is a gap that is not connected to the interconnector,
The first connection portion and the first non-connection portion are alternately arranged and formed,
The solar cell according to claim 1, wherein the surface shape of the first non-connection portion is a shape in which a tip portion on the first connection portion side is an arc shape. A bus bar electrode and a plurality of linear finger electrodes extending from the bus bar electrode are provided on the first main surface of the semiconductor substrate,
The bus bar electrode includes a first connection part for connecting to the interconnector, and a first non-connection part that is an opening not connected to the interconnector,
The first connection portion and the first non-connection portion are alternately arranged and formed,
The solar cell according to claim 1, wherein the surface shape of the first non-connection portion is a shape in which a tip portion on the first connection portion side is an arc shape. The detour part which bypasses said 1st non-connecting part and is electrically connected between said 1st connecting parts arranged on both sides of said 1st non-connecting part is characterized by the above-mentioned. The solar cell described. 4. The solar cell according to claim 1, wherein a surface shape of the first non-connection portion is a circle, an ellipse, or a track. On the second main surface opposite to the first main surface of the semiconductor substrate, second connection portions for connecting to the interconnector and second non-connecting portions not connected to the interconnector are alternately formed. The solar cell according to claim 1, wherein the solar cell is provided. The length of the first non-connection portion in the arrangement direction of the first connection portion and the first non-connection portion of the second non-connection portion facing the first non-connection portion across the semiconductor substrate, The solar cell according to claim 5 , wherein the solar cell is shorter than a length in an arrangement direction of the second connection portion and the second non-connection portion. The solar cell according to claim 5 , comprising a portion where the second non-connection portion is not formed at a position facing the first non-connection portion and the semiconductor substrate. A solar cell string in which a plurality of solar cells according to claim 5 are connected, wherein the first connection portion of the first solar cell and the second connection portion of the second solar cell in the solar cells adjacent to each other. Are connected to the same interconnector. The interconnector has at least one portion corresponding to the first non-connecting portion and a portion corresponding to the second non-connecting portion having a small cross-sectional area portion in which the cross-sectional area of the interconnector is locally reduced. The solar cell string according to claim 8 , wherein the solar cell string is arranged. A solar cell module, wherein the solar cell string according to claim 8 or 9 is sealed with a sealing material.

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