JP2014017277A - Solar cell and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell and a solar cell module which have improved photoelectric conversion efficiency.SOLUTION: A length L4 along a first direction y of that portion 24a1 of a second finger electrode part 24a which is positioned closer to one side in the first direction y than a first bus bar part 23a is shorter than a length L2 along the first direction y of that portion 22b of a first finger electrode part 22 which is positioned closer to the one side in the first direction y than the first bus bar part 23a.

Description

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

  In recent years, solar cells have attracted a great deal of attention as an energy source with a low environmental load. A solar cell has a photoelectric conversion unit that generates carriers such as electrons and holes by receiving light, and an electrode that collects carriers generated in the photoelectric conversion unit. As an electrode for collecting the carriers, for example, as described in Patent Document 1 below, the electrode extends along one direction on the main surface of the photoelectric conversion unit and is perpendicular to the one direction. An electrode including a plurality of linear finger electrode portions arranged along other directions and a bus bar portion electrically connecting the plurality of finger electrodes is widely used.

JP 2010-186862 A

  In recent years, there has been an increasing demand for further improving the photoelectric conversion efficiency of solar cells.

  This invention is made | formed in view of this point, The objective is to provide the solar cell and solar cell module which have the improved photoelectric conversion efficiency.

  The solar cell concerning this invention has a photoelectric conversion part and an electrode. The electrode is disposed on one main surface of the photoelectric conversion unit. The electrode has a plurality of first finger electrode portions, a second finger electrode portion, and a first bus bar portion. The plurality of first finger electrode portions extend along the first direction. The plurality of first finger electrode portions are arranged along a second direction perpendicular to the first direction. The second finger electrode portion is disposed between the adjacent first finger electrode portions. The second finger electrode portion extends along the first direction. The first bus bar portion is electrically connected to the first and second finger electrode portions. The first bus bar portion intersects the first and second finger electrode portions. The length along the first direction of the portion located on one side in the first direction relative to the first bus bar portion of the second finger electrode portion is longer than that of the first bus bar portion of the first finger electrode portion. Is shorter than the length along the first direction of the portion located on one side of the first direction.

  The solar cell module according to the present invention includes a plurality of solar cells and a wiring material. Each of the plurality of solar cells includes a photoelectric conversion unit and an electrode. The electrode is disposed on one main surface of the photoelectric conversion unit. The wiring material electrically connects adjacent solar cells. The electrode has a plurality of first finger electrode portions and a second finger electrode portion. The plurality of first finger electrode portions extend along the first direction. The plurality of first finger electrode portions are arranged along a second direction perpendicular to the first direction. The second finger electrode portion is disposed between the adjacent first finger electrode portions. The second finger electrode portion extends along the first direction. The wiring material is electrically connected to the first and second finger electrode portions. The wiring material intersects with the first and second finger electrode portions. The length along the first direction of the portion located on one side in the first direction with respect to the wiring material of the second finger electrode portion is larger in the first direction than the wiring material of the first finger electrode portion. It is shorter than the length along the 1st direction of the part located in one side.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell and solar cell module which have the improved photoelectric conversion efficiency can be provided.

1 is a schematic cross-sectional view of a solar cell module according to a first embodiment. It is a schematic plan view of the light receiving surface of the solar cell in the first embodiment. It is the schematic-drawing enlarged plan view which expanded a part of light-receiving surface of the solar cell in 1st Embodiment. It is the schematic-drawing enlarged plan view which expanded a part of light-receiving surface of the solar cell in 1st Embodiment. It is a schematic plan view of the back surface of the solar cell in the first embodiment. It is a schematic diagram for demonstrating the electric current which flows through a 1st finger electrode part. It is a schematic plan view of the light receiving surface of the solar cell in the first modification. It is a schematic plan view of a light receiving surface of a solar cell in a second modification. It is the schematic expanded plan view which expanded a part of electrode of the solar cell in a 3rd modification. It is a schematic plan view of the light receiving surface of the solar cell in the second embodiment. It is the schematic expanded plan view which expanded a part of light-receiving surface of the solar cell in 2nd Embodiment. It is the schematic expanded plan view which expanded a part of light-receiving surface of the solar cell in 2nd Embodiment. It is a graph showing the relationship between the distance between the 1st finger electrode parts which adjoin in Experimental examples 1 and 2, and photoelectric conversion efficiency. It is a graph showing the improvement rate of the photoelectric conversion efficiency with respect to L4 / L2.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiments are merely examples. The present invention is not limited to the following embodiments.

  Moreover, in each drawing referred in embodiment etc., the member which has a substantially the same function shall be referred with the same code | symbol. The drawings referred to in the embodiments and the like are schematically described, and the ratio of the dimensions of the objects drawn in the drawings may be different from the ratio of the dimensions of the actual objects. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.

(First embodiment)
(Schematic configuration of solar cell module 1)
As shown in FIG. 1, the solar cell module 1 includes a plurality of solar cells 10 arranged along the x direction. The plurality of solar cells 10 are electrically connected by the wiring material 11. Specifically, a plurality of solar cells 10 are electrically connected in series or in parallel by electrically connecting adjacent solar cells 10 with the wiring material 11. The wiring member 11 and the solar cell 10 are bonded by an adhesive 12. As the adhesive 12, solder or a resin adhesive can be used. When a resin adhesive is used as the adhesive 12, the resin adhesive may have an insulating property or may have an anisotropic conductivity.

  The plurality of solar cells 10 arranged in the x direction are electrically connected to each other by the wiring material 11. First and second protection members 14 and 15 are disposed on the light receiving surface side and the back surface side of the plurality of solar cells 10. A sealing material 13 is provided between the solar cell 10 and the first protective member 14 and between the solar cell 10 and the second protective member 15. The plurality of solar cells 10 are sealed with the sealing material 13.

  In addition, the material of the sealing material 13 and the 1st and 2nd protection members 14 and 15 is not specifically limited. The sealing material 13 can be formed of a light-transmitting resin such as ethylene / vinyl acetate copolymer (EVA) or polyvinyl butyral (PVB).

  The first and second protective members 14 and 15 can be formed of glass, resin, or the like, for example. For example, you may comprise one of the 1st and 2nd protection members 14 and 15 by the resin film which interposed metal foil, such as aluminum foil. In this embodiment, the 1st protection member 14 is arrange | positioned at the back surface side of the solar cell 10, and is comprised by the resin film which interposed metal foil, such as aluminum foil. The 2nd protection member 15 is arrange | positioned at the light-receiving surface side of the solar cell 10, and consists of glass or translucent resin.

  On the outer periphery of the laminate having the first protective member 14, the sealing material 13, the plurality of solar cells 10, the sealing material 13, and the second protective member 15, a metal frame such as Al is provided as necessary. A body (not shown) is attached. Moreover, the terminal box for taking out the output of the solar cell 10 outside is provided in the surface of the 1st protection member 14 as needed.

(Structure of solar cell 10)
As shown in FIG. 2, the solar cell 10 has a photoelectric conversion unit 20. The photoelectric conversion unit 20 is a member that generates carriers such as electrons and holes by receiving light. For example, the photoelectric conversion unit 20 may include a crystalline semiconductor substrate having one conductivity type, and may have a semiconductor junction such as a pn junction or a pin junction. In addition, the photoelectric conversion unit 20 is disposed on one main surface of a crystalline semiconductor substrate having one conductivity type and the first amorphous semiconductor having another conductivity type. It may have a layer and a second amorphous semiconductor layer which is disposed on the other main surface of the crystalline semiconductor substrate and has one conductivity type. Further, the photoelectric conversion unit 20 may have a semiconductor substrate in which an n-type dopant diffusion region and a p-type dopant diffusion region are exposed on the surface.

  An electrode 21 a is disposed on the light receiving surface 20 a of the photoelectric conversion unit 20. On the other hand, an electrode 21b is disposed on the back surface 20b of the photoelectric conversion unit 20 shown in FIG. In the present embodiment, the electrode 21b has substantially the same configuration as the electrode 21b. However, in this invention, the structure of the electrode distribute | arranged on the back surface of a photoelectric conversion part is not specifically limited. The electrode arranged on the back surface of the photoelectric conversion unit may be, for example, a planar electrode provided so as to cover substantially the entire back surface.

  The material of the electrodes 21a and 21b is not particularly limited as long as it is a conductive material. Each of the electrodes 21a and 21b can be made of, for example, a metal such as silver, copper, aluminum, titanium, nickel, or chromium, or an alloy containing one or more of these metals. In addition, the electrodes 21a and 21b may be configured by, for example, a stacked body of a plurality of conductive layers made of the above metals or alloys. The formation method of the electrodes 21a and 21b is not particularly limited. The electrodes 21a and 21b can be formed using a conductive paste such as an Ag paste, for example. The electrodes 21a and 21b can be formed using, for example, a sputtering method, a vapor deposition method, a screen printing method, a plating method, or the like.

  The electrode 21a includes a plurality of first finger electrode portions 22, a plurality of second finger electrode portions 24a, a plurality of third finger electrode portions 24b, and first and second bus bar portions 23a, 23b. Have.

  Each of the plurality of first finger electrode portions 22 extends to the vicinity of the end portion of the photoelectric conversion portion 20 along the y direction perpendicular to the x direction. Each of the plurality of first finger electrode portions 22 is linear. For this reason, the plurality of first finger electrode portions 22 are parallel to each other. The plurality of first finger electrode portions 22 are arranged at predetermined intervals along the x direction.

  In addition, the number of the 1st finger electrode part 22 is not specifically limited, According to the magnitude | size of the solar cell 10, a required characteristic, etc., it can set suitably. The number of the first finger electrode portions 22 can be, for example, 30 to 60. The distance L10 between the first finger electrode portions 22 (see FIG. 3) and the width W2 of the first finger electrode portion 22 can also be appropriately set according to the required characteristics of the solar cell 10. An interval L10 between the first finger electrode portions 22 can be set to, for example, about 2 mm to 4 mm. The width W2 of the first finger electrode portion 22 can be set to, for example, about 0.05 mm to 0.1 mm.

  The second finger electrode portion 24a is provided corresponding to the first bus bar portion 23a. The second finger electrode portions 24a are disposed between the first finger electrode portions 22 adjacent in the x direction. The 2nd finger electrode part 24a is distribute | arranged to the y1 side part rather than the center of the light-receiving surface 20a. The second finger electrode portion 24a extends along the y direction. The 2nd finger electrode part 24a is linear. For this reason, the second finger electrode portion 24 a is parallel to the first finger electrode portion 22.

  The third finger electrode part 24b is provided corresponding to the second bus bar part 23b. Similarly to the second finger electrode portion 24a, the third finger electrode portion 24b is also arranged between the first finger electrode portions 22 adjacent in the x direction. The 3rd finger electrode part 24b is distribute | arranged to the y2 side part rather than the center of the light-receiving surface 20a. The third finger electrode portion 24b extends along the y direction. The third finger electrode portion 24b is linear. For this reason, the 3rd finger electrode part 24b is parallel to each of the 1st finger electrode part 22 and the 2nd finger electrode part 24a.

  Each of the 2nd and 3rd finger electrode parts 24a and 24b is arranged in the approximate center between the 1st finger electrode parts 22 which adjoin in the x direction. That is, a distance L11 between the center line of the second finger electrode portion 24a and the center line of the first finger electrode portion 22 disposed on one side in the x direction of the second finger electrode portion 24a (see FIG. 3) and the center line of the second finger electrode portion 24a and the center line of the first finger electrode portion 22 arranged on the other side in the x direction of the second finger electrode portion 24a The distance L12 is substantially equal and is about ½ of the distance L10 between the center lines of the adjacent first finger electrode portions 22 and 22. A distance L14 between the center line of the third finger electrode portion 24b and the center line of the first finger electrode portion 22 disposed on one side in the x direction of the third finger electrode portion 24b (see FIG. 4). L15 between the center line of the third finger electrode portion 24b and the center line of the first finger electrode portion 22 disposed on the other side in the x direction of the third finger electrode portion 24b. Is approximately equal and is about ½ of the distance L10 between the center lines of the adjacent first finger electrode portions 22 and 22. Therefore, in this embodiment, L11 = L12 = L14 = L15≈ (1/2) · L10.

  The widths W3 and W6 of the second and third finger electrode portions 24a and 24b are not particularly limited. The widths W3 and W6 of the second and third finger electrode portions 24a and 24b may be the same as or different from the width W2 of the first finger electrode portion 22, respectively. The widths W3 and W6 of the second and third finger electrode portions 24a and 24b can be set to about 0.04 mm to 0.1 mm, for example.

  Each of the first and second bus bar portions 23a, 23b is electrically connected to the first to third finger electrode portions 22, 24a, 24b. Specifically, the first bus bar portion 23a is electrically connected to the first and second finger electrode portions 22, 24a. The second bus bar portion 23b is electrically connected to the first and third finger electrode portions 22, 24b. Each of the first and second bus bar portions 23a, 23b intersects the first to third finger electrode portions 22, 24a, 24b. Specifically, the first bus bar portion 23a intersects the first and second finger electrode portions 22, 24a. The second bus bar portion 23b intersects with the first and third finger electrode portions 22, 24b. In the present embodiment, specifically, each of the first and second bus bar portions 23a and 23b is linear. Each of the first and second bus bar portions 23a and 23b extends along the x direction. The first bus bar portion 23a is relatively disposed on the y1 side, and the second bus bar portion 23b is relatively disposed on the y2 side.

  When the wiring member 11 is bonded by solder, the widths W1 and W4 of the first and second bus bar portions 23a and 23b are made larger than the width W2 of the first finger electrode portion 22, respectively. When the wiring member 11 is bonded with a resin adhesive, the widths W1 and W4 of the first and second bus bar portions 23a and 23b are substantially the same as or slightly larger than the width W2 of the first finger electrode portion 22, respectively. Each of width W1, W4 of the 1st and 2nd bus-bar parts 23a and 23b can be about 0.1 mm-2.0 mm, for example.

  In the present embodiment, the length L4 along the y direction of the outer portion 24a1 located on the y1 side in the y direction with respect to the first bus bar portion 23a of the second finger electrode portion 24a is the first finger electrode portion 22. It is shorter than the length L2 along the y direction of the outer portion 22b located on the y1 side in the y direction from the first bus bar portion 23a (L4 <L2). Specifically, the length L4 is 0.2 times or more and less than 1 time the length L2 (0.2L2 ≦ L4 <L2).

  The length L7 along the y direction of the outer portion 24b1 located on the y2 side in the y direction with respect to the second bus bar portion 23b of the third finger electrode portion 24b is the second bus bar of the first finger electrode portion 22. It is shorter than the length L3 along the y direction of the outer portion 22c located on the y2 side in the y direction from the portion 23b (L7 <L3). Specifically, the length L7 is 0.2 times or more and less than 1 time the length L3 (0.2L3 ≦ L7 <L3).

  The length L5 along the y direction of the inner portion 24a2 located on the y2 side in the y direction from the first bus bar portion 23a of the second finger electrode portion 24a and the second bus bar portion of the third finger electrode portion 24b The lengths L5 and L6 along the y direction of the inner portion 24b2 located on the y1 side in the y direction with respect to 23b are defined between the first and second bus bar portions 23a and 23b of the first finger electrode portion 22. It is shorter than 1/2 of the length L1 along the y direction of the portion 22a (L5 <(1/2) L1, L6 <(1/2) L1). Specifically, the lengths L5 and L6 are 0.1 times or more and less than 1/2 times the length L1, that is, 0.2 times or more and less than 1 time 1/2 of the length L1 (0. 2 ((1/2) L1) ≦ L5 <(1/2) L1, 0.2 ((1/2) L1) ≦ L6 <(1/2) L1).

  In this embodiment, L1 = 2L2 = 2L3 and L4 = L5 = L6 = L7.

  By the way, in a solar cell in which an electrode having a plurality of finger electrode portions and a bus bar portion is arranged, the finger electrode portion has a portion with a large amount of current flowing during power generation and a portion with a small amount. For example, focusing on the outer portion 22b of the first finger electrode portion 22, as shown in FIG. 6, carriers generated on both sides of the tip portion are collected at the tip portion of the outer portion 22b. On the other hand, carriers generated on both sides of the base end portion are collected at the base end portion of the outer portion 22b, and carriers collected on the front end side of the base end portion flow toward the bus bar portion 23a. . Therefore, in the outer portion 22b, the amount of current flowing increases as it approaches the base end side (bus bar portion 23a) side. As described above, a relatively small current flows in a portion of the first finger electrode portion 22 that is away from the bus bar portions 23a and 23b, whereas in a portion close to the bus bar portions 23a and 23b, a relatively small current flows. A large current flows. Therefore, in the solar cell in which only the first finger electrode portion 22 is provided as the finger electrode portion and the second and third finger electrode portions 24a and 24b are not provided, the first finger electrode portion 22 There is a problem that the resistance loss in the portion close to the bus bar portion becomes large and the photoelectric conversion efficiency is lowered.

  One method of reducing the resistance loss in the portion of the first finger electrode portion close to the bus bar portion is to reduce the electrical resistance of the first finger electrode portion by increasing the width of the first finger electrode portion. Can be considered. However, in that case, the ratio of the portion covered with the electrode on the light receiving surface increases.

  Further, as another method for reducing the resistance loss in the portion near the bus bar portion of the first finger electrode portion, it is conceivable to reduce the pitch of the first finger electrode portion. In this case, since the amount of current flowing through each first finger electrode portion can be reduced, the resistance loss can be reduced. However, even in this case, the ratio of the portion covered with the electrode on the light receiving surface increases.

  Therefore, when only the first finger electrode portion is provided as the finger electrode portion, it is difficult to sufficiently increase the photoelectric conversion efficiency. On the other hand, in this embodiment, in addition to the first finger electrode portion 22, second and third finger electrode portions 24a and 24b are provided. And these 2nd and 3rd finger electrode parts 24a and 24b are provided adjacent to the part close | similar to the bus-bar parts 23a and 23b among the area | regions between the adjacent 1st finger electrode parts 22 and 22. Yes. For this reason, in the photoelectric conversion unit 20, carriers generated in the portions close to the bus bar portions 23 a and 23 b are collected not only by the first finger electrode unit 22 but also by the second and third finger electrode units 24 a and 24 b. Thus, the concentration on the first finger electrode portion 22 is suppressed. Therefore, it is possible to reduce the amount of current flowing through the portions of the first finger electrode portion 22 close to the bus bar portions 23a and 23b. Therefore, the resistance loss in the first finger electrode portion 22 can be reduced.

  In addition, the second and third finger electrode portions 24a and 24b are provided only in portions near the bus bar portions 23a and 23b in the y direction, and are not provided on the entire light receiving surface 20a. For this reason, instead of providing the second and third finger electrode portions, the ratio of the portion covered with the electrode 21a of the light receiving surface 20a is increased as compared with the case where the number of the first finger electrode portions is increased. Can be reduced. That is, the resistance loss in the first finger electrode portion 22 can be reduced while suppressing a decrease in the light receiving area. Therefore, the photoelectric conversion efficiency of the solar cell 10 and consequently the solar cell module 1 can be effectively increased.

  From the viewpoint of further improving the photoelectric conversion efficiency, 0.2L2 ≦ L4 <L2, 0.2L3 ≦ L7 <L3, 0.2 ((1/2) L1) ≦ L5 <(1/2) L1,. 2 ((1/2) L1) ≦ L6 <(1/2) L1 is preferable. If L4 to L7 are too small, the effect of improving the resistance loss in the first finger electrode portion 22 may not be sufficiently obtained, so it is considered that the photoelectric conversion efficiency may not be sufficiently increased. On the other hand, if L4 to L7 are too large, the light receiving area may be too small, and it is considered that the photoelectric conversion efficiency may not be sufficiently increased.

  Hereinafter, modified examples of the first embodiment and other examples of preferred embodiments in which the present invention is implemented will be described. In the following description, members having substantially the same functions as those of the first embodiment are referred to by the same reference numerals, and description thereof is omitted. In the second embodiment, FIG. 1 is referred to in common with the first embodiment.

(First modification)
In the first embodiment, the example in which each of the bus bar portions 23a and 23b is linear has been described. However, in the present invention, the bus bar portion does not necessarily have to be linear. For example, as shown in FIG. 7, each of the bus bar portions 23a, 23b may extend in a zigzag shape along the x direction. In this case, the wiring member 11 is preferably connected using a resin adhesive. The width of the bus bar portions 23 a and 23 b is substantially equal to the width of the first finger electrode portion 22.

  In the solar cell 10 having the zigzag bus bar portions 23 a and 23 b shown in FIG. 7, the second and third finger electrode portions 24 a and 24 b are provided symmetrically with respect to the wiring member 11.

  In addition, in the said 1st Embodiment and this modification, the example with which two bus-bar parts were distribute | arranged on one main surface was demonstrated. However, the present invention is not limited to this configuration. For example, three, four, or five or more bus bar portions may be arranged.

(Second modification)
In the first embodiment, the example in which the first finger electrode portion 22 is formed so as to extend from the y1 side end portion of the light receiving surface 20a to the y2 side end portion has been described. However, the present invention is not limited to this configuration. For example, the plurality of first finger electrode portions 22 may be arranged along the y direction. For example, in this modification, as shown in FIG. 8, each of the plurality of first finger electrode portions 22 is divided into one side portion 22a1 and the other side portion 22a2.

  In the first embodiment, the example in which the two bus bar portions 23 a and 23 b intersect the first finger electrode portion 22 has been described. However, the present invention is not limited to this configuration. One or three or more bus bar portions may intersect the first finger electrode portion. In this case, for each of the bus bar portions, a finger electrode portion having a short length is provided between the adjacent first finger electrode portions.

  In the example shown in FIG. 8, an example is described in which two sets of electrically connected bus bar portions, relatively long finger electrode portions, and relatively short finger electrode portions are provided. A set or 5 or more sets may be provided.

(Third Modification)
In the first embodiment, an example in which one second finger electrode portion 24a and one third finger electrode portion 24b are arranged between the first finger electrode portions 22 adjacent in the x direction. explained. However, the present invention is not limited to this configuration. For example, as shown in FIG. 9, a plurality of second and third finger electrode portions 24 a and 24 b may be disposed between the first finger electrode portions 22 adjacent in the x direction. In that case, each of L4 to L7 is preferably as short as the second and third finger electrode portions 24a and 24b that are closer to the center in the x direction between the adjacent first finger electrode portions 22. By doing so, the resistance loss in the 1st finger electrode part 22 can be made small, suppressing the reduction | decrease of a light-receiving area.

  However, if the number of the second and third finger electrode portions 24a and 24b located between the first finger electrode portions 22 adjacent in the x direction is excessive, the distance between the adjacent first finger electrode portions 22 is increased. Tends to cause recombination of minority carriers. Therefore, the number of the second and third finger electrode portions 24a and 24b located between the first finger electrode portions 22 adjacent in the x direction is preferably 5 or less.

(Second Embodiment)
In the first embodiment, the bus bar portions 23a and 23b are provided, and the example in which the wiring member 11 is electrically connected to the electrode 21a mainly in the bus bar portions 23a and 23b has been described. However, the present invention is not limited to this configuration.

  For example, as shown in FIG. 10, the bus bar portions 23a and 23b may not be provided, and the electrode 21a may be configured by the first to third finger electrode portions 22, 24a and 24b. In that case, from the viewpoint of increasing the photoelectric conversion efficiency of the solar cell module 1, the length L4 along the y direction of the outer portion 24a1 located on the y1 side in the y direction with respect to the wiring member 11a of the second finger electrode portion 24a. Is preferably shorter than the length L2 along the y direction of the outer portion 22b located on the y1 side in the y direction with respect to the wiring member 11a of the first finger electrode portion 22 (L2 <L4). The length L4 is more preferably 0.2 times or more and less than 1 time the length L2 (0.2L2 ≦ L4 <L2).

  The length L7 along the y direction of the outer portion 24b1 located on the y2 side in the y direction relative to the wiring material 11b of the third finger electrode portion 24b is larger than the wiring material 11b of the first finger electrode portion 22 in the y direction. It is preferable that the outer portion 22c located on the y2 side is shorter than the length L3 along the y direction (L7 <L3). The length L7 is more preferably 0.2 times or more and less than 1 time the length L3 (0.2L3 ≦ L7 <L3).

  The length L5 along the y direction of the inner portion 24a2 located on the y2 side in the y direction relative to the wiring material 11a of the second finger electrode portion 24a and the y direction relative to the wiring material 11b of the third finger electrode portion 24b. The lengths L5 and L6 along the y direction of the inner portion 24b2 located on the y1 side are the lengths along the y direction of the portion 22a located between the wiring members 11a and 11b of the first finger electrode portion 22. It is preferably shorter than 1/2 of L1 (L5 <(1/2) L1, L6 <(1/2) L1). The lengths L5 and L6 are more preferably 0.1 times or more and less than 1/2 times the length L1, that is, 0.2 times or more and less than 1 time 1/2 of the length L1 (0.2 ((1/2) L1) ≦ L5 <(1/2) L1, 0.2 ((1/2) L1) ≦ L6 <(1/2) L1).

  In addition, when using an electrode having a so-called bus bar-less structure in which the bus bar portions 23a and 23b are not provided, it is preferable to connect the wiring member 11 to the finger electrode portion 24 using a resin adhesive having anisotropic conductivity.

(Experimental example 1)
A solar cell having substantially the same configuration as that of the solar cell 10 in the first embodiment is manufactured by changing the distance L10 between the first finger electrode portions 22 with various design parameters, and photoelectric conversion is performed. Efficiency was measured. The results are shown in FIG.

(Design parameters of solar cell fabricated in Experimental Example 1)
Photoelectric conversion part: 125mm square with chamfered corners L1: 60mm
L2 = L3: 30mm
L4 = L5: 16mm
L6 = L7: 16mm
W3 = W6: 45 μm
L11 = L12 = L14 = L15

(Experimental example 2)
Except that the second and third finger electrode portions are not provided, a solar cell having a configuration substantially similar to that of the solar cell fabricated in Experimental Example 1 is set to a distance between the first finger electrode portions. Various changes were made, and the photoelectric conversion efficiency was measured. The results are shown in FIG.

  From the graph of FIG. 13, in Experimental Example 1, the photoelectric conversion efficiency was maximized when the distance L10 between the first finger electrode portions was 3.1 mm. On the other hand, in Experimental Example 2, the photoelectric conversion efficiency was maximized when the distance L10 was 1.8 mm. The maximum photoelectric conversion efficiency in Experimental Example 1 was 0.21% higher than the photoelectric conversion efficiency in Experimental Example 2. From this result, it can be seen that the photoelectric conversion efficiency can be increased by providing the second and third finger electrode portions in addition to the first finger electrode portion.

(Experimental example 3)
Except that the distance L10 is 3.1 mm at which the photoelectric conversion efficiency is maximized, solar cells having substantially the same configuration as the solar cell manufactured in Experimental Example 1 are L4 / L2, L7 / L3. , L5 / ((1/2) L1), L6 / ((1/2) L1) were variously changed to produce photoelectric conversion efficiency. In Experimental Example 3, L4 / L2 = L7 / L3 = L5 / ((1/2) L1) = L6 / ((1/2) L1). Then, L4 / L2 = 0, that is, the improvement rate obtained by subtracting the reference value from the obtained photoelectric conversion efficiency on the basis of the photoelectric conversion efficiency when the second and third finger electrode portions are not provided. As calculated. The results are shown in FIG. From the results shown in FIG. 14, by setting L4 / L2, L7 / L3, L5 / ((1/2) L1), and L6 / ((1/2) L1) to 0.2 or more and less than 1, It can be seen that the conversion efficiency can be further increased.

DESCRIPTION OF SYMBOLS 1 ... Solar cell module 10 ... Solar cell 11 ... Wiring material 20 ... Photoelectric conversion part 20a ... Light-receiving surface 20b ... Back surface 21a, 21b ... Electrode 22 ... 1st finger electrode part 23a ... 1st bus-bar part 23b ... 2nd Bus bar portion 24a ... second finger electrode portion 24b ... third finger electrode portion

Claims (11)

A solar cell having a photoelectric conversion unit and an electrode disposed on one main surface of the photoelectric conversion unit,
The electrode is
A plurality of first finger electrode portions extending along a first direction and arranged along a second direction perpendicular to the first direction;
A second finger electrode portion disposed between the adjacent first finger electrode portions and extending along the first direction;
A first bus bar portion that is electrically connected to the first and second finger electrode portions and intersects the first and second finger electrode portions;
Have
The length along the first direction of the portion of the second finger electrode portion located on one side of the first direction with respect to the first bus bar portion is the length of the first finger electrode portion. The solar cell which is shorter than the length along the said 1st direction of the part located in the one side of the said 1st direction rather than a 1st bus-bar part.   The length along the first direction of the portion of the second finger electrode portion located on one side of the first direction with respect to the first bus bar portion is the length of the first finger electrode portion. 2. The solar cell according to claim 1, wherein the solar cell is 0.2 times or more the length along the first direction of a portion located on one side of the first direction with respect to the first bus bar portion. The electrode is
A third finger electrode portion disposed between the adjacent first finger electrode portions and extending along the first direction;
The first and third finger electrode portions are electrically connected to each other and intersect the first and third finger electrode portions on the other side in the first direction with respect to the first bus bar portion. 2 busbars,
Further comprising
The length along the first direction of the portion located on the other side of the first direction from the second bus bar portion of the third finger electrode portion is the length of the first finger electrode portion. The solar cell according to claim 1 or 2, wherein a portion located on the other side in the first direction with respect to the second bus bar portion is shorter than a length along the first direction.   The length along the first direction of the portion located on the other side of the first direction from the second bus bar portion of the third finger electrode portion is the length of the first finger electrode portion. 4. The solar cell according to claim 3, which is 0.2 times or more of a length along the first direction of a portion located on the other side in the first direction with respect to the second bus bar portion. The length along the first direction of the portion of the second finger electrode portion located on the other side in the first direction with respect to the first bus bar is the first length of the first finger electrode portion. Shorter than half of the length along the first direction of the portion located between one bus bar portion and the second bus bar portion,
The length along the first direction of the portion of the third finger electrode portion located on one side of the first direction from the first bus bar is the first length of the first finger electrode portion. 5. The solar cell according to claim 3, wherein a portion located between one bus bar portion and the second bus bar portion is shorter than ½ of a length along the first direction. 6. The length along the first direction of the portion of the second finger electrode portion located on the other side in the first direction with respect to the first bus bar is the first length of the first finger electrode portion. 1 or more times the length along the first direction of the portion located between one bus bar portion and the second bus bar portion,
The length along the first direction of the portion of the third finger electrode portion located on one side of the first direction from the first bus bar is the first length of the first finger electrode portion. 6. The solar cell according to claim 5, wherein the solar cell is at least 0.1 times the length along the first direction of a portion located between one bus bar portion and the second bus bar portion. A plurality of the second finger electrode portions are arranged along the second direction between the adjacent first finger electrode portions,
The length along the first direction of the portion of the second finger electrode portion located on one side of the first direction with respect to the first bus bar portion is the first finger electrode portion adjacent to the second finger electrode portion. The solar cell according to any one of claims 1 to 6, which is shorter as it is closer to the center in the second direction.   The solar cell according to claim 1, wherein the plurality of first finger electrode portions and the second finger electrode portion are parallel to each other.   The solar cell according to claim 1, wherein the first main surface is a light receiving surface. A solar cell module comprising a plurality of solar cells having a photoelectric conversion unit and an electrode disposed on one main surface of the photoelectric conversion unit, and a wiring member for electrically connecting the adjacent solar cells. There,
The electrode is
A plurality of first finger electrode portions extending along a first direction and arranged along a second direction perpendicular to the first direction;
A second finger electrode portion disposed between the adjacent first finger electrode portions and extending along the first direction;
Have
The wiring member is electrically connected to the first and second finger electrode portions, and intersects the first and second finger electrode portions,
The length along the first direction of the portion located on one side of the first direction with respect to the wiring material of the second finger electrode portion is larger than the wiring material of the first finger electrode portion. The solar cell module is shorter than the length along the first direction of the portion located on one side of the first direction.   The length along the first direction of the portion located on one side of the first direction with respect to the wiring material of the second finger electrode portion is larger than the wiring material of the first finger electrode portion. 11 is a solar cell module according to claim 10, which is 0.2 times or more of a length along the first direction of a portion located on one side of the first direction.

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