Solar cell and method of manufacturing a solar cell

Abstract

The present application provides a solar cell in which a collector is reliably connected to an electrode. A solar cell (1) of one embodiment of the present application includes a semiconductor substrate (11), a plurality of first semiconductor layers (21) and a plurality of second semiconductor layers (22) which are alternately provided over the semiconductor substrate (11), a first base electrode (41) and a second base electrode (42) which are stacked over the first semiconductor layers (21) and the second semiconductor layers (22), a first electrode insulating material (61) which is stacked over a first insulating region complementary to a first connection region of the first base electrode (41) and a second electrode insulating material (62) which is stacked over a second insulating region complementary to a second connection region of the second base electrode (42), an intermediate insulating material (71) which is stacked over a region of the first semiconductor layers (21) where the first base electrode (41) is not stacked and a region of the second semiconductor layers (22) where the second base electrode (42) is not stacked, a first collector (81) which is stacked across the second electrode insulating material (62) and the intermediate insulating material (71) so as to connect between a plurality of the first connection regions, and a second collector (82) which is stacked across the first electrode insulating material (61) and the intermediate insulating material (71) so as to connect between a plurality of the second connection regions.

Description

Technical Field

[0001] This invention relates to solar cells and methods for manufacturing solar cells. Background Technology

[0002] A back-contact type solar cell is known, comprising: a plurality of strip-shaped first semiconductor layers and second semiconductor layers alternately formed on the back side of a semiconductor substrate; a plurality of strip-shaped first base electrodes and second base electrodes respectively stacked on the first semiconductor layers and second semiconductor layers; a plurality of first connecting electrodes and second connecting electrodes alternately stacked on the first base electrodes and second base electrodes; a first current collector configured to be disposed between the plurality of first connecting electrodes; and a second current collector configured to be disposed between the plurality of second connecting electrodes.

[0003] In such solar cells, it is also known that, 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, an insulating material is laminated in the region where the first base electrode intersects with the second current collector and the region where the second base electrode intersects with the first current collector (see, for example, Patent Document 1).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-159286

[0005] In manufacturing back-contact solar cells as described above, the first and second current collectors, which are made of metal wires or the like, need to be positioned and bonded using solder or the like for the first and second connecting electrodes. If the spacing between the first and second semiconductor layers is reduced to improve current collection efficiency, the first and second connecting electrodes are miniaturized and narrowed in spacing. As a result, positioning the first and second current collectors becomes more difficult, raising concerns that the connection between the first and second current collectors and the first and second connecting electrodes may become unreliable. Summary of the Invention

[0006] The objective of this invention is to provide a solar cell with a reliable connection between the current collector and the connecting electrode, and a method for manufacturing the solar cell.

[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, wherein the plurality of first semiconductor layers and the plurality of second semiconductor layers are respectively formed as strips extending along a first direction on the back side of the semiconductor substrate and are alternately disposed in a second direction intersecting the first direction; a strip-shaped first base electrode, the strip-shaped first base electrode being stacked on the back side of the central portion of the first semiconductor layer in the second direction; a strip-shaped second base electrode, the strip-shaped second base electrode being stacked on the back side of the central portion of the second semiconductor layer in the second direction; a first electrode insulating material, the first electrode insulating material being stacked on the back side of a first insulating region complementary to a first connection region of each of the first base electrodes, the first connection region being disposed in the region of each of the first base electrodes in a manner arranged along the second direction; and a second electrode. An insulating material, wherein the second electrode insulating material is stacked on the back side of the second connection region of each of the second base electrodes, which is complementary to the second connection region, and the second connection region is disposed in the region of each of the second base electrodes in a manner arranged in a second direction at a position offset from the first connection region in the first direction; an intermediate insulating material, wherein the intermediate insulating material is stacked on the back side of the region of the first semiconductor layer not stacked with the first base electrode and the back side of the region of the second semiconductor layer not stacked with the second base electrode; a first current collector, wherein the first current collector is stacked across the second electrode insulating material and the intermediate insulating material in a manner that connects the plurality of the first connection regions; and a second current collector, wherein the second current collector is stacked across the first electrode insulating material and the intermediate insulating material in a manner that connects the plurality of the second connection regions.

[0008] In the solar cell of the present invention described above, the materials of the first current collector and the second current collector may also be solder or conductive adhesive.

[0009] The solar cell of the present invention may further include: a first connecting electrode, wherein the first connecting electrode is stacked on the back side of the first connecting region of the first base electrode; and a second connecting electrode, wherein the second connecting electrode is stacked on the back side of the second connecting region of the second base electrode.

[0010] The solar cell of the present invention may further include: a first transparent electrode, wherein the first transparent electrode is sandwiched between the first semiconductor layer and the first substrate electrode; and a second transparent electrode, wherein the second transparent electrode is sandwiched between the second semiconductor layer and the second substrate electrode.

[0011] In the solar cell of the present invention described above, the intermediate insulating material may also be white.

[0012] Another aspect of the present invention provides a method for manufacturing a solar cell comprising the following steps: alternately disposing of a plurality of strip-shaped first semiconductor layers and a plurality of strip-shaped second semiconductor layers extending along a first direction on the back side of a semiconductor substrate in a second direction intersecting the first direction; stacking a metal layer such that it covers the back side of the first semiconductor layers and the second semiconductor layers; and including a portion of a first strip-shaped region on the back side of the metal layer that overlaps with the central portion of each of the first semiconductor layers in the second direction (i.e., a plurality of first connection regions arranged along the second direction), and a portion of a plurality of second strip-shaped regions on the back side of the metal layer that overlaps with the central portion of each of the second semiconductor layers in the second direction (i.e., a plurality of second connection regions arranged along the second direction at a position offset from the first connection regions). A first conductive paste is laminated in the connection area; a first insulating material is laminated in the first insulating region of the first strip region complementary to the first connection region and the second insulating region of the second strip region complementary to the second connection region on the back side of the metal layer; the portion of the metal layer other than the first strip region and the second strip region is removed by etching using the first conductive paste and the first insulating material as a mask; a second insulating material is laminated on the back side of the first semiconductor layer and the second semiconductor layer exposed by the etching; and the second conductive paste is laminated in strips extending along the second direction in the first insulating material, the region of the plurality of first connection regions crossing the back side of the first insulating material, and the region of the plurality of second connection regions crossing the second connection regions.

[0013] According to the present invention, a solar cell with reliable connection between the current collector and the connecting electrode can be provided. Attached Figure Description

[0014] Figure 1 This is a back view of a solar cell according to one embodiment of the present invention.

[0015] Figure 2 yes Figure 1 A sectional view of a solar cell along line AA.

[0016] Figure 3 It means Figure 1 A flowchart of the steps involved in manufacturing a solar cell.

[0017] Figure 4A It means Figure 1 A cross-sectional view of one step in the manufacturing process of a solar cell.

[0018] Figure 4B It means Figure 1 The manufacturing method of solar cells Figure 4AA cross-sectional view of the next process.

[0019] Figure 4C It means Figure 1 The manufacturing method of solar cells Figure 4B A cross-sectional view of the next process.

[0020] Figure 4D It means Figure 1 The manufacturing method of solar cells Figure 4C A cross-sectional view of the next process.

[0021] Figure 4E It means Figure 1 The manufacturing method of solar cells Figure 4D A cross-sectional view of the next process.

[0022] Figure 4F It means Figure 1 The manufacturing method of solar cells Figure 4E A cross-sectional view of the next process.

[0023] Figure 4G It means Figure 1 The manufacturing method of solar cells Figure 4F A cross-sectional view of the next process.

[0024] Figure 4H It means Figure 1 The manufacturing method of solar cells Figure 4G A cross-sectional view of the next process.

[0025] Figure 5 It was used Figure 1 The back view of the solar cell string. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, for convenience, there may be instances where shaded lines, component reference numerals, etc., are omitted; however, in such cases, refer to other drawings. Additionally, for ease of observation, the dimensions of various components in the drawings have been adjusted.

[0027] Figure 1 This is a back view of a solar cell 1 according to one embodiment of the present invention. Figure 2 This is a sectional view of solar cell 1 along line AA.

[0028] Solar cell 1 is a so-called heterojunction back-contact type solar cell unit. The solar cell 1 includes: a semiconductor substrate 11; a plurality of first semiconductor layers 21 and a plurality of second semiconductor layers 22, wherein the plurality of first semiconductor layers 21 and the plurality of second semiconductor layers 22 are formed as strips extending along a first direction on the back side (the side opposite to the light incident surface) of the semiconductor substrate 11 and are alternately arranged in a second direction intersecting the first direction; a plurality of first transparent electrodes 31 and a plurality of second transparent electrodes 32, wherein the plurality of first transparent electrodes 31 and the plurality of second transparent electrodes 32 are stacked in strips extending along the first direction on the central portion of the back side of the first semiconductor layers 21 and the second semiconductor layers 22 in a second direction; a plurality of first base electrodes 41 and a plurality of second base electrodes 42, wherein the plurality of first base electrodes 41 and the plurality of second base electrodes 42 are stacked substantially across the entire back side of the first transparent electrodes 31 and the second transparent electrodes 32; a plurality of first connecting electrodes 51, wherein the plurality of first connecting electrodes 51 are partially stacked on the back side of each first base electrode 41 and are arranged side by side in the second direction; and a plurality of second connecting electrodes 52, wherein the plurality of second connecting electrodes 51 are stacked on the back side of each first base electrode 41 and are arranged side by side in the second direction. 2. Partially stacked on the back side of each second base electrode 42, and configured to be offset from the first connecting electrode 51 and arranged side by side in a second direction; a first electrode insulating material 61, which is stacked on the area of ​​the first base electrode 41 where there is no first connecting electrode 51; a second electrode insulating material 62, which is stacked on the area of ​​the second base electrode 42 where there is no second connecting electrode 52; an intermediate insulating material 71, which is stacked on the back side of the area of ​​the first semiconductor layer 21 where there is no first transparent electrode 31 and the first base electrode 41, and on the back side of the area of ​​the second semiconductor layer 22 where there is no second transparent electrode 32 and the second base electrode 42; a first current collector 81, which is stacked across the second electrode insulating material 62 and the intermediate insulating material 71 in a manner that connects the plurality of first connecting electrodes 51; and a second current collector 82, which is stacked across the first electrode insulating material 61 and the intermediate insulating material 71 in a manner that connects the plurality of second connecting electrodes 52.

[0029] The semiconductor substrate 11 is formed from a crystalline silicon material such as monocrystalline silicon or polycrystalline silicon. For example, the semiconductor substrate 11 is an n-type semiconductor substrate doped with an n-type dopant. Phosphorus (P) is an example of an n-type dopant. The semiconductor substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light-receiving surface to generate photocarriers (electrons and holes). By using crystalline silicon as the material for the semiconductor substrate 11, a relatively high output (stable output independent of illuminance) can be obtained even when the dark current is relatively small and the intensity of the incident light is low.

[0030] The first semiconductor layer 21 and the second semiconductor layer 22 have different conductivity types. For example, the first semiconductor layer 21 is formed of a p-type semiconductor, and the second semiconductor layer 22 is formed of an n-type semiconductor. The first semiconductor layer 21 and the second semiconductor layer 22 can, for example, be formed of amorphous silicon material containing dopants that impart the desired conductivity type. Examples of p-type dopants include boron (B), and examples of n-type dopants include phosphorus (P) as described above.

[0031] The first semiconductor layer 21 and the second semiconductor layer 22 are each formed as strips extending along 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 arranged in a second direction intersecting the first direction. The first semiconductor layers 21 and the second semiconductor layers 22 are preferably arranged to cover approximately the entire surface of the semiconductor substrate 11. The first semiconductor layers 21 and the second semiconductor layers 22 attract charge carriers generated within the semiconductor substrate 11 to collect charge.

[0032] The first transparent electrode 31 and the second transparent electrode 32 are thin layers that collect electricity 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. In addition, the first transparent electrode 31 and the second transparent electrode 32 function as an intermediate layer to prevent a decrease in adhesion and an increase in 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.

[0033] The first transparent electrode 31 and the second transparent electrode 32 are stacked in a way that they do not contact each other, and are spread over the approximate entire length of the first semiconductor layer 21 and the second semiconductor layer 22 in the second direction with a width smaller than that of the first semiconductor layer 21 and the second semiconductor layer 22.

[0034] 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) and zinc oxide (ZnO).

[0035] A first base electrode 41 is stacked on each of the first transparent electrodes 31 in a manner extending along a first direction, and a second base electrode 42 is stacked on each of the second transparent electrodes 32 in a manner extending along the first direction. The first base electrode 41 and the second base electrode 42 extract charge 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 of a metal such as copper.

[0036] First connecting electrodes 51 are stacked on the back side of the first connecting region provided on each first base electrode 41 in a manner arranged along the second direction. Second connecting electrodes 52 are stacked on the back side of the second connecting region provided on each second base electrode 42 in a manner arranged along the second direction at a position offset from the first connecting electrodes in the first direction. Conversely, the region where the first connecting electrodes 51 are stacked is the first connecting region, and the region where the second connecting electrodes 52 are stacked is the second connecting region. The size and shape of the first connecting region and the second connecting region are not particularly limited as long as electrical connection can be achieved. However, in this embodiment, the first connecting region is a rectangular region formed at the center of the second direction of each first base electrode 41, and the second connecting region is a rectangular region formed at the center of the second direction of each second base electrode 42.

[0037] A first connecting electrode 51 is sandwiched between a first base electrode 41 and a first current collector 81, thereby electrically connecting the first base electrode 41 and the first current collector 81. A second connecting electrode 52 is sandwiched between a second base electrode 42 and a second current collector 82, thereby electrically connecting the second base electrode 42 and the second current collector 82. The first connecting electrode 51 and the second connecting electrode 52 are raised such that the height of the first base electrode 41 and the second base electrode 42 relative to the connection surfaces of the first current collector 81 and the second current collector 82 is approximately equal to the back surfaces of the first electrode insulating material 61 and the second electrode insulating material 62, thereby making the electrical connection between the first current collector 81 and the second current collector 82 and the first connecting electrode 51 and the second connecting electrode 52 reliable.

[0038] The first connecting electrode 51 and the second connecting electrode 52 are arranged offset in a first direction in a manner that prevents short circuits with the first collector 81 and the second collector 82. Furthermore, the first connecting electrode 51 and the second connecting electrode 52 are preferably arranged at the center of the first base electrode 41 and the second base electrode 42 in a manner that reduces the resistance at both ends of the first base electrode 41 and the second base electrode 42.

[0039] The first connecting electrode 51 and the second connecting electrode 52 can be formed, for example, from a conductive paste such as silver paste. In order to improve the adhesion to the first base electrode 41 and the second base electrode 42, the first connecting electrode 51 and the second connecting electrode 52 are preferably formed from the same material as the first base electrode 41 and the second base electrode 42.

[0040] A first electrode insulating material 61 is laminated on the back side of the first base electrode 41 in the region complementary to the first connection region (the region of the first base electrode 41 after removing the first connection region from the overall region when viewed from above), thereby covering the portion of the first base electrode 41 exposed from the first connection electrode 51. A second electrode insulating material 62 is laminated on the back side of the second base electrode 42 in the region complementary to the second connection region (the region of the second base electrode 42 after removing the second connection region from the overall region when viewed from above), 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, for example, of an insulating material with epoxy resin as the main component.

[0041] The first electrode insulating material 61 can also be partially stacked with the first connecting electrode 51 in a manner that does not form a gap between it and the first connecting electrode 51 even if there is an error in the stacking position. Similarly, the second electrode insulating material 62 can also be partially stacked with the second connecting electrode 52. In addition, the first electrode insulating material 61 and the second electrode insulating material 62 can also surround the first connecting electrode 51 and the second connecting electrode 52 respectively in a manner that cooperates with the first connecting electrode 51 and the second connecting electrode 52 and forms a straight strip-shaped region on the side edge. That is to say, the first electrode insulating material 61 and the second electrode insulating material 62 can also have openings that expose the first connecting electrode 51 or the second connecting electrode 52.

[0042] The intermediate insulating material 71 is configured to fill the area on the back side of the semiconductor substrate 11, where the first connecting electrode 51, the second connecting 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, in conjunction with the first connecting electrode 51, the second connecting electrode 52, the first electrode insulating material 61, and the second electrode insulating material 62, continuously covers the back side of the semiconductor substrate 11. The intermediate insulating material 71 is formed, for example, of an insulating material with epoxy resin as its main component.

[0043] The intermediate insulating material 71 is preferably white. That is, the intermediate insulating material 71 preferably contains a light-diffusing material. As a result, light that has passed through the semiconductor substrate 11, the first semiconductor layer 21 and the second semiconductor layer 22 is reflected and returned to the semiconductor substrate 11, thereby increasing the amount of charge carriers generated.

[0044] The first current collector 81 and the second current collector 82 are respectively connected to the first connecting electrode 51 and the second connecting electrode 52, and are thus 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 of solder or conductive adhesive.

[0045] Figure 3 The steps of the method for manufacturing solar cell 1 are described. Figure 3 The solar cell manufacturing method is one embodiment of the solar cell manufacturing method of the present invention.

[0046] The solar cell manufacturing method of this embodiment includes: a semiconductor layer stacking process (step S1), a transparent electrode stacking process (step S2), a metal layer stacking process (step S3), a first conductive paste stacking process (step S4), a first insulating material stacking process (step S5), an etching process (step S6), a second insulating material stacking process (step S7), and a second conductive paste stacking process (step S8).

[0047] In the semiconductor layer stacking process of step S1, as Figure 4A As shown, semiconductor material is stacked on the back side of the semiconductor substrate 11, thereby alternately forming a plurality of strip-shaped first semiconductor layers 21 and a plurality of strip-shaped second semiconductor layers 22 extending along the first direction in the second direction. Specifically, the first semiconductor layers 21 and the second semiconductor layers 22 can be formed sequentially by stacking semiconductor material using a film deposition technique such as CVD, by forming a mask on the back side of the semiconductor substrate 11.

[0048] In the transparent electrode stacking process of step S2, as Figure 4B As shown, a transparent electrode layer 30, made of the material forming the first transparent electrode 31 and the second transparent electrode 32, is stacked on the entire back side of the semiconductor substrate 11 in such a way that it covers the first semiconductor layer 21 and the second semiconductor layer 22. The transparent electrode layer 30 can be stacked, for example, using a film deposition technique such as sputtering.

[0049] In the metal layer lamination process of step S3, such as Figure 4C As shown, a metal layer 40, made of the metal forming the first base electrode 41 and the second base electrode 42, is stacked such that it covers the back side of the first semiconductor layer 21 and the second semiconductor layer 22 through a transparent electrode layer 30. This metal layer 40 can be stacked, for example, by sputtering, electroplating, or the like.

[0050] In the first conductive paste lamination process of step S4, such as Figure 4DAs shown, a portion of a plurality of first strip-shaped regions overlapping the central portion of each first semiconductor layer 21 in the second direction on the back side of the metal layer 40 (i.e., a plurality of first connection regions arranged along the second direction), and a portion of a plurality of second strip-shaped regions overlapping the central portion of each second semiconductor layer 22 in the second direction on the back side of the metal layer 40 (i.e., a plurality of second connection regions arranged along the second direction at a position offset from the first connection regions) are laminated with a first conductive paste, thereby forming a first connection electrode 51 and a second connection electrode 52. Furthermore, the first strip-shaped regions are the regions where the first base electrode 41 is formed, and the second strip-shaped regions are the regions where the second base electrode 42 is formed.

[0051] The first conductive paste may contain metal particles, such as silver paste, an adhesive such as resin or glass to bond the metal particles together, and a solvent to adjust the viscosity during printing. Such a first conductive paste can be selectively laminated using printing techniques such as screen printing.

[0052] Therefore, the first conductive paste lamination process includes a process of printing the first conductive paste and a process of firing the printed first conductive paste. If the processes described later include a firing process, the firing process can also be performed simultaneously with those firing processes. In this case, in order to prevent the first conductive paste from deforming during other processes after printing, the first conductive paste lamination process preferably includes a process for drying the first conductive paste by evaporating the solvent from the first conductive paste and printing it.

[0053] In the first insulating material lamination process of step S5, such as Figure 4E As shown, a first insulating material is laminated on the back side of the metal layer 40, comprising a first insulating region complementary to the first connecting region in the first strip region and a second insulating region complementary to the second connecting region in the second strip region. The first insulating material laminated on the first insulating region forms a first electrode insulating material 61, and the first insulating material laminated on the second insulating region forms a second electrode insulating material 62.

[0054] As the first insulating material, a paste-like resin composition, for example, with a thermosetting resin as the main component, can be used. Such a first insulating material can be selectively laminated using printing techniques such as screen printing.

[0055] Therefore, the first insulating material lamination process includes a process of printing the first insulating material and a process of firing (thermal curing) the printed first conductive paste. When other processes are performed after printing and before firing, in order to prevent the printed first insulating material from deforming during the period before firing, the first insulating material lamination process may also include a process of drying the viscosity-adjusting solvent contained in the resin composition after printing.

[0056] The first insulating material lamination process can also be performed before the first conductive paste lamination process. When the first insulating material lamination process is performed after the first conductive paste lamination process, the contact area of ​​the first connecting electrode 51 and the second connecting electrode 52 relative to the first base electrode 41 and the second base electrode 42 can be increased. When the first insulating material lamination process is performed before the first conductive paste lamination process, the contact area of ​​the first connecting electrode 51 and the second connecting electrode 52 relative to the first current collector 81 and the second current collector 82 can be increased. There is a concern that the first conductive paste and the first insulating material may bleed during printing, but the ease of bleeding may vary depending on the material and printing conditions. Therefore, by considering the size of each component and the bleeding potential of the first conductive paste and the first insulating material, the order of the first insulating material lamination process and the first conductive paste lamination process can be selected, thereby enabling more reliable connection between the components.

[0057] In the etching process of step S6, such as Figure 4F As shown, the transparent electrode layer 30 and the metal layer 40, excluding the first and second strip regions, are removed by etching using a first conductive paste and a first insulating material as a mask. Thus, 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.

[0058] In this way, 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, are used as etching masks for the transparent electrode layer 30 and the metal layer 40. This eliminates the need for a dedicated etching mask formation process and a stripping process, thereby reducing the manufacturing cost of the solar cell 1.

[0059] In the second insulating layer lamination process of step S7, as follows Figure 4G As shown, a second insulating material is stacked on the back side of the first semiconductor layer 21 and the second semiconductor layer 22 exposed by etching, thereby forming an intermediate insulating material 71.

[0060] In the second conductive paste lamination process of step S8, such as Figure 4H As shown, a second conductive paste is stacked in strips extending along a second direction in the first conductive paste, the first insulating material, and the regions spanning multiple first connection areas across the back side of the first insulating material and the regions spanning multiple second connection areas. Thus, a first current collector 81 and a second current collector 82 are formed from the second insulating material.

[0061] As a second conductive paste, it is possible to form a first current collector 81 and a second current collector 82 with low resistance. Therefore, it is particularly preferable to use a solder paste containing solder particles and flux. By using solder paste as the second conductive paste, the first current collector 81 and the second current collector 82, which are not easily deformed, can be formed by drying or reflowing the solder paste in the second insulating layer lamination process. Then, when connecting the solar cell 1 to other solar cells 1 or external circuits, a portion of the solder used to form the first current collector 81 and the second current collector 82 can be used for connection with other conductors.

[0062] The second conductive paste can be selectively laminated using printing techniques such as screen printing. Therefore, compared to the case where components such as metal wires are positioned and connected relative to the first connecting electrode 51 and the second connecting electrode 52 while being connected, the first current collector 81 and the second current collector 82 can be accurately and reliably connected to the first connecting electrode 51 and the second connecting electrode 52. At this time, an intermediate insulating material 71 is formed, thereby preventing short circuits caused by the first current collector 81 and the second current collector 82 contacting 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.

[0063] As described above, the solar cell 1 can be manufactured relatively inexpensively, and the connection between the first current collector 81 and the second current collector 82 and the first connecting electrode 51 and the second connecting electrode 52 is highly reliable.

[0064] Figure 5 An example is shown of a solar cell string 100 having multiple solar cells 1. The solar cell string 100 includes multiple solar cells 1 arranged side by side along a first direction, and wiring material 2 connecting a first current collector 81 of one side of two adjacent solar cells 1 to a second current collector 82 of the other side of the solar cell 1.

[0065] The solar cell string 100 is a so-called shingled solar cell string. Specifically, in the solar cell string 100, each solar cell 1 is configured such that the end on one side of a first direction overlaps the back side of the end on the other side of the first direction of an adjacent solar cell 1.

[0066] The wiring material 2 is not particularly limited, but can be formed, for example, from a strip of braided metal wire, a strip of metal foil, or a metal wire. The wiring material 2 can be bonded to the first current collector 81 and the second current collector 82 using conductive paste that forms the first current collector 81 and the second current collector 82. As an example, when the first current collector 81 and the second current collector 82 are formed from solder, by heating the back side of the multiple solar cells 1 arranged side-by-side while the wiring material 2 is positioned appropriately, the first current collector 81 and the second current collector 82 can be reflowed and connected. The first current collector 81 and the second current collector 82 can also be connected using the heat from the heating process when sealing the solar cell string 100 to the solar cell module.

[0067] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and various modifications and variations are possible. For example, the solar cell of the present invention may not have a transparent electrode. In addition, the solar cell of the present invention may also include, in addition to the above-described constituent elements, an intrinsic semiconductor layer, a passivation layer, an anti-reflective film, a protective film, and other further constituent elements.

[0068] In the solar cell of the present invention, the first connecting electrode and the second connecting electrode can be omitted. Therefore, the solar cell of the present invention is not limited to the solar cell manufactured by the solar cell manufacturing method of the present invention. As an example, the solar cell of the present invention can also be manufactured by forming a first insulating material and a second insulating material by laminating a first insulating material after forming a first base electrode and a second base electrode using a subtractive or additive method.

[0069] The solar cells of the present invention can also be electrically connected in parallel through one or more wiring materials, that is, the first current collectors of two or more solar cells are connected to each other and the second current collectors are connected to each other.

[0070] In the solar cell manufacturing method of 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 insulating material formed in the first connection region and the second electrode insulating material formed in the second connection region, the first conductive paste lamination process can be omitted. In other words, in the solar cell of the present invention, the first connection electrode and the second connection electrode can be omitted.

[0071] Explanation of reference numerals in the attached figures

[0072] 1…Solar cell; 2…Wiring material; 11…Semiconductor substrate; 21…First semiconductor layer; 22…Second semiconductor layer; 30…Transparent electrode layer; 31…First transparent electrode; 32…Second transparent electrode; 40…Metal layer extending along the second direction; 41…First base electrode; 42…Second base electrode; 51…First connecting electrode; 52…Second connecting electrode; 61…First electrode insulating material; 62…Second electrode insulating material; 71…Intermediate insulating material; 81…First current collector; 82…Second current collector; 100…Solar cell string.

Claims

1. A solar cell, characterized in that, have: Semiconductor substrate; A plurality of first semiconductor layers and a plurality of second semiconductor layers are respectively formed in the form of strips extending along a first direction on the back side of the semiconductor substrate, and are alternately arranged in a second direction intersecting the first direction; A strip-shaped first base electrode, the strip-shaped first base electrode being stacked on the back side of the central portion of the first semiconductor layer in the second direction; A strip-shaped second base electrode, the strip-shaped second base electrode being stacked on the back side of the central portion of the second semiconductor layer in the second direction; A first electrode insulating material is stacked on the back side of a first insulating region that is complementary to a first connection region of each first base electrode. The first connection regions are arranged in a manner along the second direction in the region of each first base electrode. The second electrode insulating material is stacked on the back side of the second insulating region that is complementary to the second connection region of each second base electrode. The second connection region is disposed in the region of each second base electrode in a manner that is arranged in the second direction at a position offset from the first connection region in the first direction. An intermediate insulating material is stacked on the back side of the region of the first semiconductor layer where the first base electrode is not stacked, and on the back side of the region of the second semiconductor layer where the second base electrode is not stacked. A first current collector is stacked across the second electrode insulating material and the intermediate insulating material in a manner that connects multiple first connection regions; as well as The second current collector is stacked across the first electrode insulating material and the intermediate insulating material in a manner that connects a plurality of second connection regions.

2. The solar cell according to claim 1, characterized in that, The first current collector and the second current collector are made of solder or conductive adhesive.

3. The solar cell according to claim 1 or 2, characterized in that, Further features include: A first connecting electrode, the first connecting electrode being stacked on the back side of the first connecting region of the first base electrode; and The second connecting electrode is stacked on the back side of the second connecting region of the second base electrode.

4. The solar cell according to claim 1 or 2, characterized in that, Further features include: A first transparent electrode, the first transparent electrode being sandwiched between the first semiconductor layer and the first substrate electrode; and The second transparent electrode is sandwiched between the second semiconductor layer and the second substrate electrode.

5. The solar cell according to claim 1 or 2, characterized in that, The intermediate insulating material is white.

6. A method for manufacturing a solar cell, characterized in that, It has the following processes: Multiple strip-shaped first semiconductor layers and multiple strip-shaped second semiconductor layers extending along a first direction are alternately disposed on the back side of a semiconductor substrate in a second direction intersecting the first direction. A metal layer is stacked in such a manner that it covers the back side of the first semiconductor layer and the second semiconductor layer; A portion of a plurality of first strip regions overlapping the central portion of each of the first semiconductor layers in the second direction on the back side of the metal layer, i.e., a plurality of first connection regions arranged along the second direction, and a portion of a plurality of second strip regions overlapping the central portion of each of the second semiconductor layers in the second direction on the back side of the metal layer, i.e., a plurality of second connection regions arranged along the second direction at a position offset from the first connection regions, are stacked with a first conductive paste. A first insulating material is laminated between a first insulating region complementary to the first connecting region in the first strip region and a second insulating region complementary to the second connecting region in the second strip region on the back side of the metal layer. The portion of the metal layer other than the first strip region and the second strip region is removed by etching using the first conductive paste and the first insulating material as a mask. A second insulating material is stacked on the back side of the first semiconductor layer and the second semiconductor layer exposed by the etching; as well as The first conductive paste, the first insulating material, and the regions of the plurality of first connection regions spanning the back side of the first insulating material and the regions spanning the plurality of second connection regions are respectively stacked in strips extending along the second direction.

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