Solar cell and solar cell manufacturing method

Abstract

The present invention provides a solar cell in which the connections of current collectors to connection electrodes are reliable. A solar cell (1) according to one embodiment of the present invention comprises: a semiconductor substrate (11); a plurality of first semiconductor layers (21) and a plurality of second semiconductor layers (22) provided in an alternating manner on the semiconductor substrate (11); first base electrodes (41) and second base electrodes (42) layered on the first semiconductor layers (21) and the second semiconductor layers (22); a first electrode insulating material (61) layered in a first insulation area complementary to a first connection area of the first base electrodes (41); a second electrode insulating material (62) layered in a second insulating area complementary to a second connection area of the second base electrodes (42); an intermediate insulating material (71) layered in an area in which the first base electrodes (41) of the first semiconductor layers (21) are not layered and in an area in which the second base electrodes (42) of the second semiconductor layers (22) are not layered; a first current collector (81) layered extending across the second electrode insulating material (62) and the intermediate insulating material (71) so as to connect the plurality of first connection areas; and a second current collector (82) layered extending across the first electrode insulating material (61) and the intermediate insulating material (71) so as to connect the plurality of second connection areas.

Description

[Technical Field]

[0001] The present invention relates to a solar cell and a method for manufacturing a solar cell. [Background technology]

[0002] A back-contact solar cell is known which includes a plurality of strip-shaped first semiconductor layers and second semiconductor layers formed alternately on the back surface of a semiconductor substrate, a plurality of strip-shaped first base electrodes and second base electrodes stacked on the first semiconductor layers and second semiconductor layers, respectively, a plurality of first connection electrodes and second connection electrodes stacked alternately on the first base electrodes and second base electrodes, a first current collector arranged to bridge between the plurality of first connection electrodes, and a second current collector arranged to bridge between the plurality of second connection electrodes.

[0003] In such solar cells, in order to prevent short circuits between the first base electrode and the second current collector, and between the second base electrode and the first current collector, a configuration is also known in which an insulating material is laminated in the area where the first base electrode intersects with the second current collector and in the area where the second base electrode intersects with the first current collector (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-159286 Summary of the Invention [Problem to be solved by the invention]

[0005] When manufacturing a back-contact solar cell as described above, it is necessary to position the first and second current collectors, which are made of metal wires or the like, relative to the first and second connection electrodes and join them with solder, etc. If the arrangement pitch of the first and second semiconductor layers is reduced to improve current collection efficiency, the first and second connection electrodes will be made smaller and have a narrower pitch, making it difficult to position the first and second current collectors and potentially resulting in unreliable connection of the first and second current collectors to the first and second connection electrodes.

[0006] An object of the present invention is to provide a solar cell in which the current collector is reliably connected to the connection electrode, and a method for manufacturing the solar cell. [Means for solving the problem]

[0007] A solar cell according to one aspect of the present invention includes a semiconductor substrate; a plurality of first semiconductor layers and a plurality of second semiconductor layers each formed in a strip shape extending in a first direction on a back surface side of the semiconductor substrate and arranged alternately in a second direction intersecting the first direction; a strip-shaped first base electrode stacked on the back surface side of a central portion of the first semiconductor layer in the second direction; a strip-shaped second base electrode stacked on the back surface side of a central portion of the second semiconductor layer in the second direction; a first electrode insulator stacked on the back surface side of a first insulating region of each of the first base electrodes that is complementary to a first connection region set on each of the first base electrodes so as to be aligned in the second direction; and a first electrode insulator stacked on the back surface side of each of the second base electrodes. The semiconductor device comprises: a second electrode insulating material stacked on the back side of a second connection region complementary to a second connection region set on each of the second base electrodes so as to be aligned in the second direction at a position offset from the first connection region in the first direction; an intermediate insulating material stacked on the back side of an area of ​​the first semiconductor layer where the first base electrode is not stacked and on the back side of an area of ​​the second semiconductor layer where the second base electrode is not stacked; a first current collector stacked across the second electrode insulating material and the intermediate insulating material to connect between the multiple first connection regions; and a second current collector stacked across the first electrode insulating material and the intermediate insulating material to connect between the multiple second connection regions.

[0008] In the solar cell according to the above aspect of the present invention, the first current collector and the second current collector may be made of a material such as solder or a conductive adhesive.

[0009] The solar cell according to the above aspect of the present invention may further comprise a first connection electrode stacked on the back side of the first connection region of the first base electrode, and a second connection electrode stacked on the back side of the second connection region of the second base electrode.

[0010] The solar cell according to the above aspect of the present invention may further comprise a first transparent electrode interposed between the first semiconductor layer and the first base electrode, and a second transparent electrode interposed between the second semiconductor layer and the second base electrode.

[0011] In the solar cell according to the above aspect of the present invention, the intermediate insulating material may be white.

[0012] A solar cell manufacturing method according to another aspect of the present invention includes the steps of: providing, on a back surface side of a semiconductor substrate, a plurality of strip-shaped first semiconductor layers and a plurality of strip-shaped second semiconductor layers, each extending in a first direction, alternately in a second direction intersecting the first direction; stacking a metal layer so as to cover the back surface sides of the first semiconductor layers and the second semiconductor layers; and stacking a first conductive paste on a plurality of first connection regions, which are part of first strip regions on the back surface side of the metal layer and overlap with central portions of each of the first semiconductor layers in the second direction, and which are aligned in the second direction; and on a plurality of second connection regions, which are part of second strip regions on the back surface side of the metal layer and overlap with central portions of each of the second semiconductor layers in the second direction, and which are aligned in the second direction at positions shifted from the first connection regions; The method includes the steps of: stacking a first insulating material on the back surface side of the metal layer in a first insulating region complementary to the first connection region in the first strip-shaped region, and in a second insulating region complementary to the second connection region in the second strip-shaped region; removing portions of the metal layer other than the first strip-shaped region and the second strip-shaped region by etching using the first conductive paste and the first insulating material as a mask; stacking a second insulating material on the back surface sides of the first semiconductor layer and the second semiconductor layer exposed by the etching; and stacking a second conductive paste in strip shapes extending in the second direction in regions spanning the first insulating material and the multiple first connection regions and regions spanning the multiple second connection regions on the back surface side of the first insulating material. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a solar cell in which the current collector is reliably connected to the connection electrode. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a rear view of a solar cell according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the solar cell of FIG. 1 taken along line AA. [Figure 3] 2 is a flowchart showing the steps of a method for manufacturing the solar cell of FIG. 1. [Figure 4A]2 is a cross-sectional view showing one step in the method for manufacturing the solar cell of FIG. 1. [Figure 4B] 4B is a cross-sectional view showing the step subsequent to FIG. 4A in the method for manufacturing the solar cell of FIG. [Figure 4C] 4B in the method of manufacturing the solar cell of FIG. 1. FIG. [Figure 4D] 4D is a cross-sectional view showing the step subsequent to FIG. 4C in the method for manufacturing the solar cell of FIG. [Figure 4E] 4D in the method of manufacturing the solar cell of FIG. 1. FIG. [Figure 4F] 4E is a cross-sectional view showing a step subsequent to FIG. 4E in the method for manufacturing the solar cell of FIG. [Figure 4G] 4F in the method for manufacturing the solar cell of FIG. 1. FIG. [Figure 4H] 4G in the method of manufacturing the solar cell of FIG. 1. FIG. [Figure 5] FIG. 2 is a rear view of a solar cell string using the solar cell of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, hatching and component reference numerals may be omitted. In such cases, other drawings should be referenced. Furthermore, the dimensions of various components in the drawings have been adjusted for clarity.

[0016] Fig. 1 is a back view of a solar cell 1 according to one embodiment of the present invention, Fig. 2 is a cross-sectional view of the solar cell 1 taken along line AA.

[0017] The solar cell 1 is a so-called heterojunction back-contact solar cell. The solar cell 1 includes a semiconductor substrate 11, a plurality of first semiconductor layers 21 and a plurality of second semiconductor layers 22 formed in strip shapes extending in a first direction on the back side (opposite the light incident surface) of the semiconductor substrate 11 and arranged alternately in a second direction intersecting the first direction, a plurality of first transparent electrodes 31 and a plurality of second transparent electrodes 32 stacked in strip shapes extending in the first direction at the center in the second direction on the back sides of the first semiconductor layers 21 and the second semiconductor layers 22, a plurality of first base electrodes 41 and a plurality of second base electrodes 42 stacked over substantially the entire back surfaces of the first transparent electrodes 31 and the second transparent electrodes 32, a plurality of first connection electrodes 51 partially stacked on the back surfaces of the first base electrodes 41 and arranged side by side in the second direction, and a plurality of first connection electrodes 51 partially stacked on the back surfaces of the second base electrodes 42 and arranged side by side in the second direction. the first base electrode 41 in an area where the first connection electrode 51 is not present, and the second base electrode 42 in an area where the second connection electrode 52 is not present; an intermediate insulating material 71 stacked on the back side of the area where the first transparent electrode 31 and the first base electrode 41 are not stacked on the first semiconductor layer 21 and the second semiconductor layer 22 in an area where the second transparent electrode 32 and the second base electrode 42 are not stacked; a first current collector 81 stacked across the second electrode insulating material 62 and the intermediate insulating material 71 to connect the plurality of first connection electrodes 51; and a second current collector 82 stacked across the first electrode insulating material 61 and the intermediate insulating material 71 to connect the plurality of second connection electrodes 52.

[0018] The semiconductor substrate 11 is formed of a crystalline silicon material such as single crystal silicon or polycrystalline silicon. The semiconductor substrate 11 is, for example, an n-type semiconductor substrate obtained by doping a crystalline silicon material with an n-type dopant. An example of the n-type dopant is phosphorus (P). The semiconductor substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light-receiving surface side and generates photocarriers (electrons and holes). By using crystalline silicon as the material for the semiconductor substrate 11, dark current is relatively small, and a relatively high output (stable output regardless of illuminance) can be obtained even when the intensity of incident light is low.

[0019] The first semiconductor layer 21 and the second semiconductor layer 22 have different conductivity types. For example, the first semiconductor layer 21 is formed from a p-type semiconductor, and the second semiconductor layer 22 is formed from an n-type semiconductor. The first semiconductor layer 21 and the second semiconductor layer 22 can be formed, for example, from an amorphous silicon material containing a dopant that imparts the desired conductivity type. An example of a p-type dopant is boron (B), and an example of an n-type dopant is the aforementioned phosphorus (P).

[0020] The first semiconductor layer 21 and the second semiconductor layer 22 are each formed in a strip shape extending in a first direction. In the solar cell 1, a plurality of first semiconductor layers 21 and a plurality of second semiconductor layers 22 are alternately provided in a second direction intersecting the first direction. The first semiconductor layer 21 and the second semiconductor layer 22 are preferably arranged so as to cover substantially the entire surface of the semiconductor substrate 11. The first semiconductor layer 21 and the second semiconductor layer 22 attract carriers generated in the semiconductor substrate 11 and collect charges.

[0021] The first transparent electrode 31 and the second transparent electrode 32 are thin layers that collect current from the first semiconductor layer 21 and the second semiconductor layer 22 and supply charge to the first base electrode 41 and the second base electrode 42. The first transparent electrode 31 and the second transparent electrode 32 also function as intermediate layers that prevent a decrease in adhesion and an increase in electrical resistance at the interface caused by differences in materials between the first semiconductor layer 21 and the second semiconductor layer 22 and the first base electrode 41 and the second base electrode 42, etc.

[0022] The first transparent electrode 31 and the second transparent electrode 32 are stacked in the second direction over approximately the entire length of the first semiconductor layer 21 and the second semiconductor layer 22, with a width smaller than that of the first semiconductor layer 21 and the second semiconductor layer 22, so as not to come into contact with each other.

[0023] The first transparent electrode 31 and the second transparent electrode 32 can be formed from the same material. Examples of materials for forming the first transparent electrode 31 and the second transparent electrode 32 include ITO (Indium Tin Oxide). Examples of the oxide include zinc oxide (ZnO), tin oxide (Tin Oxide), and zinc oxide (ZnO).

[0024] The first base electrode 41 is laminated on each of the first transparent electrodes 31 so as to extend in the first direction, and the second base electrode 42 is laminated on each of the second transparent electrodes 32 so as to extend in the first direction. The first base electrode 41 and the second base electrode 42 extract charges from the first semiconductor layer 21 and the second semiconductor layer 22 via the first transparent electrode 31 and the second transparent electrode 32. The first base electrode 41 and the second base electrode 42 are formed from a metal such as copper.

[0025] The first connection electrodes 51 are stacked on the back side of the first connection regions set on the respective first base electrodes 41 so as to be aligned in the second direction. The second connection electrodes 52 are stacked on the back side of the second connection regions set on the respective second base electrodes 42 so as to be aligned in the second direction but offset from the first connection electrodes in the first direction. Conversely, the region where the first connection electrodes 51 are stacked is the first connection region, and the region where the second connection electrodes 52 are stacked is the second connection region. The sizes and shapes of the first connection region and the second connection region are not particularly limited as long as they enable electrical connection. However, in this embodiment, the first connection region is a rectangular region in the center of each first base electrode 41 in the second direction, and the second connection region is a rectangular region in the center of each second base electrode 42 in the second direction.

[0026] The first connection electrode 51 is interposed between the first base electrode 41 and the first current collector 81, thereby electrically connecting the first base electrode 41 and the first current collector 81. The second connection electrode 52 is interposed between the second base electrode 42 and the second current collector 82, thereby electrically connecting the second base electrode 42 and the second current collector 82. The first connection electrode 51 and the second connection electrode 52 are raised so that the height positions of the connection surfaces of the first base electrode 41 and the second base electrode 42 with the first current collector 81 and the second current collector 82 are approximately equal to the rear surfaces of the first electrode insulator 61 and the second electrode insulator 62, thereby ensuring the electrical connection of the first current collector 81 and the second current collector 82 to the first connection electrode 51 and the second connection electrode 52.

[0027] The first connection electrode 51 and the second connection electrode 52 are arranged offset in the first direction to prevent a short circuit between the first current collector 81 and the second current collector 82. Furthermore, the first connection electrode 51 and the second connection electrode 52 are preferably arranged in the center of the first base electrode 41 and the second base electrode 42 in the first direction to reduce the electrical resistance from both ends of the first base electrode 41 and the second base electrode 42.

[0028] The first connection electrode 51 and the second connection electrode 52 may be formed from a conductive paste such as silver paste. The first connection electrode 51 and the second connection electrode 52 are preferably formed from the same material as the first base electrode 41 and the second base electrode 42 in order to improve adhesion to the first base electrode 41 and the second base electrode 42.

[0029] The first electrode insulating material 61 is laminated on the back side of a first insulating region, which is a region complementary to the first connection region of the first base electrode 41 (a region obtained by excluding the first connection region from the entire region of the first base electrode 41 in a plan view), thereby covering the portion of the first base electrode 41 exposed from the first connection electrode 51. The second electrode insulating material 62 is laminated on the back side of a second insulating region, which is a region complementary to the second connection region of the second base electrode 42 (a region obtained by excluding the second connection region from the entire region of the second base electrode 42 in a plan view), thereby covering the portion of the second base electrode 42 exposed from the second connection electrode 52. The first electrode insulating material 61 and the second electrode insulating material 62 are formed from an insulating material containing, for example, an epoxy resin or the like as a main component.

[0030] The first electrode insulating material 61 may be laminated so as to partially overlap the first connection electrode 51 so that no gap is formed between the first connection electrode 51 even if there is an error in the lamination position. Similarly, the second electrode insulating material 62 may be laminated so as to partially overlap the second connection electrode 52. Furthermore, the first electrode insulating material 61 and the second electrode insulating material 62 may surround the first connection electrode 51 and the second connection electrode 52, respectively, so that they, together with the first connection electrode 51 and the second connection electrode 52, form strip-shaped regions with linear side edges. In other words, the first electrode insulating material 61 and the second electrode insulating material 62 may have an opening that exposes the first connection electrode 51 or the second connection electrode 52.

[0031] The intermediate insulating material 71 is disposed so as to fill an area on the back surface side of the semiconductor substrate 11 on which the first semiconductor layer 21 and the second semiconductor layer 22 are disposed, where the first connection electrode 51, the second connection electrode 52, the first electrode insulating material 61, and the second electrode insulating material 62 are not stacked. In other words, the intermediate insulating material 71, together with the first connection electrode 51, the second connection electrode 52, the first electrode insulating material 61, and the second electrode insulating material 62, continuously covers the back surface side of the semiconductor substrate 11. The intermediate insulating material 71 is formed from an insulating material whose main component is, for example, epoxy resin.

[0032] The intermediate insulating material 71 is preferably white. That is, the intermediate insulating material 71 preferably contains a light diffusing material. This allows the light that has passed through the semiconductor substrate 11, the first semiconductor layer 21, and the second semiconductor layer 22 to be reflected back to the semiconductor substrate 11, thereby increasing the amount of carrier generation.

[0033] The first current collector 81 and the second current collector 82 connect the first connection electrode 51 and the second connection electrode 52, respectively, and are also used as terminals for extracting power from the solar cell 1. The first current collector 81 and the second current collector 82 can be formed using solder or a conductive adhesive.

[0034] Fig. 3 shows the steps of a method for manufacturing the solar cell 1. The solar cell manufacturing method of Fig. 3 is one embodiment of the solar cell manufacturing method according to the present invention.

[0035] The solar cell manufacturing method of this embodiment includes a semiconductor layer lamination process (step S1), a transparent electrode lamination process (step S2), a metal layer lamination process (step S3), a first conductive paste lamination process (step S4), a first insulating material lamination process (step S5), an etching process (step S6), a second insulating material lamination process (step S7), and a second conductive paste lamination process (step S8).

[0036] 4A, in the semiconductor layer stacking process of step S1, a plurality of strip-shaped first semiconductor layers 21 extending in a first direction and a plurality of strip-shaped second semiconductor layers 22 extending in a second direction are alternately formed by stacking semiconductor materials on the back surface side of semiconductor substrate 11. Specifically, the first semiconductor layers 21 and the second semiconductor layers 22 can be formed in order by forming a mask on the back surface of semiconductor substrate 11 and stacking semiconductor materials using a film formation technique such as CVD.

[0037] 4B, in the transparent electrode lamination process of step S2, a transparent electrode layer 30 made of a material for forming the first transparent electrode 31 and the second transparent electrode 32 is laminated on the entire back surface side of the semiconductor substrate 11 so as to cover the first semiconductor layer 21 and the second semiconductor layer 22. The transparent electrode layer 30 can be laminated by a film formation technique such as sputtering.

[0038] 4C , in the metal layer lamination process of step S3, a metal layer 40 made of a metal that forms the first base electrode 41 and the second base electrode 42 is laminated so as to cover the back surface sides of the first semiconductor layer 21 and the second semiconductor layer 22 via the transparent electrode layer 30. This metal layer 40 can be laminated by, for example, sputtering, plating, or the like.

[0039] 4D , in the first conductive paste laminating step of step S4, a first conductive paste is laminated on a plurality of first connection regions that are part of a plurality of first strip-shaped regions on the back surface side of the metal layer 40 and overlap with the central portions of the respective first semiconductor layers 21 in the second direction and are aligned in the second direction, and on a plurality of second connection regions that are part of a plurality of second strip-shaped regions on the back surface side of the metal layer 40 and overlap with the central portions of the respective second semiconductor layers 22 in the second direction and are aligned in the second direction at positions offset from the first connection regions, thereby forming a first connection electrode 51 and a second connection electrode 52. The first strip-shaped regions are regions where the first base electrode 41 is formed, and the second strip-shaped regions are regions where the second base electrode 42 is formed.

[0040] The first conductive paste may contain metal particles such as silver paste, a binder such as resin or glass that bonds the metal particles together, and a solvent that adjusts the viscosity during printing. Such a first conductive paste may be selectively laminated using a printing technique such as screen printing.

[0041] Therefore, the first conductive paste lamination step includes a step of printing the first conductive paste and a step of firing the printed first conductive paste. If a step described later includes a firing step, the firing step may be performed simultaneously with the firing step. In this case, to prevent the first conductive paste from deforming during other steps after printing, the first conductive paste lamination step preferably includes a step of volatilizing the solvent from the printed first conductive paste and drying it.

[0042] 4E, in the first insulating material laminating step S5, a first insulating material is laminated in a first insulating region complementary to the first connection region in the first strip region and in a second insulating region complementary to the second connection region in the second strip region on the back surface side of the metal layer 40. The first insulating material laminated in the first insulating region forms a first electrode insulating material 61, and the first insulating material laminated in the second insulating region forms a second electrode insulating material 62.

[0043] The first insulating material may be, for example, a paste-like resin composition containing a thermosetting resin as a main component, and may be selectively laminated using a printing technique such as screen printing.

[0044] Therefore, the first insulating material laminating step includes a step of printing the first insulating material and a step of baking (thermosetting) the printed first conductive paste. When other steps are performed after printing and before baking, the first insulating material laminating step may include a step of drying a viscosity-adjusting solvent contained in the resin composition after printing to prevent deformation of the printed first insulating material before baking.

[0045] The first insulating material laminating step may be performed before the first conductive paste laminating step. Performing the first insulating material laminating step after the first conductive paste laminating step increases the contact area between the first connection electrode 51 and the second connection electrode 52 and the first base electrode 41 and the second base electrode 42. Performing the first insulating material laminating step before the first conductive paste laminating step increases the contact area between the first connection electrode 51 and the second connection electrode 52 and the first current collector 81 and the second current collector 82. The first conductive paste and the first insulating material may bleed when printed, but the degree of bleed may vary depending on the material and printing conditions. Therefore, by selecting the order of the first insulating material laminating step and the first conductive paste laminating step taking into account the size of each component and the bleed of the first conductive paste and the first insulating material, the connection between each component can be more reliably achieved.

[0046] 4F, in the etching process of step S6, portions of the transparent electrode layer 30 and the metal layer 40 other than the first strip-shaped regions and second strip-shaped regions are removed by etching using the first conductive paste and the first insulating material as a mask. As a result, the remaining transparent electrode layer 30 forms the first transparent electrode 31 and the second transparent electrode 32, and the remaining metal layer 40 forms the first base electrode 41 and the second base electrode 42.

[0047] In this way, by using the first connecting electrode 51, the second connecting electrode 52, the first electrode insulating material 61 and the second electrode insulating material 62, which are components of the solar cell 1, as etching masks for the transparent electrode layer 30 and the metal layer 40, the process of forming and peeling off a dedicated etching mask is not required, thereby reducing the manufacturing cost of the solar cell 1.

[0048] In the second insulating layer lamination process of step S7, as shown in FIG. 4G, an intermediate insulating material 71 is formed by laminating a second insulating material on the back surface side of the first semiconductor layer 21 and the second semiconductor layer 22 exposed by etching.

[0049] In the second conductive paste laminating step S8, as shown in Fig. 4H, the second conductive paste is laminated in strip shapes extending in the second direction in the first conductive paste, the first insulating material, and the area spanning the first connection areas and the area spanning the second connection areas on the back surface of the first insulating material, respectively, thereby forming first current collector 81 and second current collector 82 from the second insulating material.

[0050] A solder paste containing solder particles and flux is particularly preferably used as the second conductive paste, because it is possible to form first current collector 81 and second current collector 82 with low electrical resistance. By using solder paste as the second conductive paste, after the solder paste is dried or reflowed in the second insulating layer lamination step to form first current collector 81 and second current collector 82 that do not easily deform, when connecting solar cell 1 to another solar cell 1 or an external circuit, part of the solder forming first current collector 81 and second current collector 82 can be used for connection with other conductors.

[0051] The second conductive paste can be selectively laminated using a printing technique such as screen printing. Therefore, compared to connecting members such as metal wires while positioning them relative to the first connection electrode 51 and the second connection electrode 52, the first current collector 81 and the second current collector 82 can be connected accurately and reliably to the first connection electrode 51 and the second connection electrode 52. At this time, the formation of the intermediate insulating material 71 makes it possible to prevent a short circuit caused by the first current collector 81 and the second current collector 82 coming into contact with the first base electrode 41, the second base electrode 42, the first transparent electrode 31, the second transparent electrode 32, the first semiconductor layer 21, the second semiconductor layer 22, and the semiconductor substrate 11.

[0052] As described above, solar cell 1 can be manufactured relatively inexpensively, and the connections of first current collector 81 and second current collector 82 to first connection electrode 51 and second connection electrode 52 are highly reliable.

[0053] 5 illustrates a solar cell string 100 having a plurality of solar cells 1. The solar cell string 100 includes a plurality of solar cells 1 arranged side by side in a first direction, and wiring material 2 that connects a first current collector 81 of one solar cell 1 to a second current collector 82 of the other solar cell 1 of two adjacent solar cells 1.

[0054] The solar cell string 100 is a solar cell string with a so-called shingling structure. Specifically, in the solar cell string 100, each solar cell 1 is arranged such that an end portion on one side in the first direction overlaps the back side of an end portion on the other side in the first direction of an adjacent solar cell 1.

[0055] The wiring material 2 is not particularly limited, and can be formed, for example, from a strip formed by weaving metal wire, a strip-shaped metal foil, a metal wire, or the like. The wiring material 2 can be joined to the first current collector 81 and the second current collector 82 by a conductive paste that forms the first current collector 81 and the second current collector 82. For example, if the first current collector 81 and the second current collector 82 are formed from solder, the wiring material 2 can be placed in an appropriate position on the back side of a plurality of solar cells 1 arranged side by side, and then heated to reflow the first current collector 81 and the second current collector 82, thereby connecting the wiring material 2. The first current collector 81 and the second current collector 82 may also be connected using heat generated during a heating process when the solar cell string 100 is sealed in a solar cell module.

[0056] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications and variations are possible. For example, the solar cell according to the present invention may not have a transparent electrode. Furthermore, the solar cell according to the present invention may include, in addition to the above-described components, further components such as an intrinsic semiconductor layer, a passivation layer, an anti-reflection film, and a protective film.

[0057] In the solar cell according to the present invention, the first connection electrode and the second connection electrode can be omitted. Therefore, the solar cell according to the present invention is not limited to one manufactured by the solar cell manufacturing method according to the present invention. For example, the solar cell according to the present invention may be manufactured by forming the first base electrode and the second base electrode by a subtractive method or an additive method, and then forming the first insulating material and the second insulating material by laminating a first insulating material.

[0058] The solar cells according to the present invention may be electrically connected in parallel, that is, the first current collectors and second current collectors of two or more solar cells may be connected together by one or more wiring members.

[0059] In the solar cell manufacturing method according to the present invention, if the second conductive paste forming the first current collector and the second current collector can be reliably filled into the openings of the first electrode insulator formed in the first connection region and the openings of the second electrode insulator formed in the second connection region, the first conductive paste laminating step can be omitted, i.e., the first connection electrode and the second connection electrode can be omitted in the solar cell according to the present invention. [Explanation of symbols]

[0060] 1. Solar cells 2 Wiring material 11 Semiconductor substrate 21 First semiconductor layer 22 Second semiconductor layer 30 Transparent electrode layer 31 1st transparent electrode 32 Second transparent electrode 40 metal layer extending in the second direction 41 First base electrode 42 Second base electrode 51 first connection electrode 52 second connection electrode 61 First electrode insulating material 62 Second electrode insulating material 71 Intermediate insulation material 81 First current collector 82 Second current collector 100 solar cell strings

Claims

1. a semiconductor substrate; a plurality of first semiconductor layers and a plurality of second semiconductor layers each formed in a strip shape extending in a first direction on a rear surface side of the semiconductor substrate and alternately provided in a second direction intersecting the first direction; a plurality of strip-shaped first base electrodes respectively stacked on a rear surface side of a central portion of the first semiconductor layer in the second direction, and a plurality of strip-shaped second base electrodes respectively stacked on a rear surface side of a central portion of the second semiconductor layer in the second direction; a plurality of first electrode insulating materials laminated on the rear surface side of each of the first base electrodes, and a plurality of second electrode insulating materials laminated on the rear surface side of each of the second base electrodes; an intermediate insulating material laminated on a rear surface side of a region of the first semiconductor layer where the first base electrode is not laminated and on a rear surface side of a region of the second semiconductor layer where the second base electrode is not laminated; a first current collector laminated across the second electrode insulating material and the intermediate insulating material, and a second current collector laminated across the first electrode insulating material and the intermediate insulating material; Equipped with a first connection region and a first insulating region complementary to the first connection region are defined in the first base electrode; a second connection region and a first insulating region complementary to the second connection region are defined in the second base electrode; the first connection region of each of the first base electrodes is set at a position aligned with the first connection region of another of the first base electrodes in the second direction, the second connection region of each of the second base electrodes is set at a position that is shifted from the first connection region in the first direction and aligned with the second connection region of another of the second base electrodes in the second direction, the first current collector connects the first connection regions arranged in the second direction; The second current collector connects the second connection regions arranged in the second direction.

2. The solar cell according to claim 1 , wherein the first current collector and the second current collector are made of a material selected from the group consisting of solder and conductive adhesive.

3. 3. The solar cell according to claim 1, further comprising: a first connection electrode stacked on a rear surface side of the first connection region of the first base electrode; and a second connection electrode stacked on a rear surface side of the second connection region of the second base electrode.

4. a first transparent electrode interposed between the first semiconductor layer and the first base electrode; a second transparent electrode interposed between the second semiconductor layer and the second base electrode; The solar cell according to claim 1 , further comprising:

5. The solar cell according to claim 1 , wherein the intermediate insulating material is white.

6. providing, on a rear surface side of a semiconductor substrate, a plurality of strip-shaped first semiconductor layers and a plurality of strip-shaped second semiconductor layers each extending in a first direction, alternately in a second direction intersecting the first direction; a step of depositing a metal layer so as to cover the back surface sides of the first semiconductor layer and the second semiconductor layer; a step of stacking a first conductive paste on a plurality of first connection regions that are part of a plurality of first strip-shaped regions on the back surface side of the metal layer and overlap with central portions of the first semiconductor layers in the second direction, and that are aligned in the second direction, and on a plurality of second connection regions that are part of a plurality of second strip-shaped regions on the back surface side of the metal layer and overlap with central portions of the second semiconductor layers in the second direction, and that are aligned in the second direction at positions shifted from the first connection regions in the first direction; depositing a first insulating material on a rear surface side of the metal layer in a first insulating region complementary to the first connection region in the first strip region and in a second insulating region complementary to the second connection region in the second strip region; removing portions of the metal layer other than the first strip-shaped regions and the second strip-shaped regions by etching using the first conductive paste and the first insulating material as a mask; stacking a second insulating material on the back surface sides of the first semiconductor layer and the second semiconductor layer exposed by the etching; a step of laminating a second conductive paste in a strip shape extending in the second direction on the first conductive paste, the first insulating material, and a region spanning the first connection regions and a region spanning the second connection regions on the back surface side of the first insulating material; A solar cell manufacturing method comprising:

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