Solar cell, solar module, and method for manufacturing a solar cell

Abstract

This invention provides a solar cell that reduces color unevenness on individual light-receiving surfaces when modularized. [Solution] The solar cell 1 comprises a crystalline silicon substrate 11 having an uneven structure on the light-receiving surface side, a first conductivity type semiconductor layer and a first electrode layer formed on the light-receiving surface side of the substrate 11, a second conductivity type semiconductor layer and a second electrode layer formed on the back side of the substrate 11, and an optical adjustment layer formed on the light-receiving surface side of the substrate 11, wherein in the substrate 11, the radius of curvature of the top portion of the uneven structure of at least a part of the peripheral Af2 on the light-receiving surface side is greater than the radius of curvature of the top portion of the uneven structure of the central Af1 on the light-receiving surface side, the uneven structure of the substrate 11 is reflected on the light-receiving surface of the solar cell 1, and in the solar cell 1, the radius of curvature of the top portion of the uneven structure of at least a part of the peripheral Af2 on the light-receiving surface side is greater than the radius of curvature of the top portion of the uneven structure of the central Af1 on the light-receiving surface side.

Description

Technical Field

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

Background Art

[0002] As solar cells, there are double-sided electrode type solar cells in which electrodes are formed on both the light-receiving surface side and the back surface side, and back-contact type (also referred to as back-contact type or back-junction type. Hereinafter referred to as back-contact type) solar cells in which electrodes are formed only on the back surface side. Patent Documents 1 and 2 disclose double-sided electrode type solar cells.

[0003] For example, a double-sided electrode type solar cell includes an optical adjustment layer (anti-reflection layer) formed on the light-receiving surface side of a crystalline silicon substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a solar cell, due to variations in film formation conditions or the position within a film formation apparatus, etc., individual variations occur in the film thickness of the optical adjustment layer on the light-receiving surface side, and as a result, individual variations occur in the color of the light-receiving surface.

[0006] Therefore, in a solar module in which a plurality of solar cells are two-dimensionally arranged, color unevenness on the light-receiving surfaces of these solar cells is likely to be conspicuous.

[0007] The present invention aims to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell that reduce color unevenness of individual light-receiving surfaces in a modularized system. [Means for solving the problem]

[0008] The inventors of the present invention have found that in a solar cell module in which multiple solar cells are arranged in a two-dimensional manner, by making the peripheral edges of the light-receiving surfaces of individual solar cells more prominent, individual solar cells can be viewed three-dimensionally, and this visual effect makes the color distribution of the light-receiving surfaces of the multiple solar cells less noticeable.

[0009] Therefore, the solar cell according to the present invention comprises a crystalline silicon substrate having an uneven structure on the light-receiving surface side, a first conductivity type semiconductor layer formed on the light-receiving surface side of the substrate, a second conductivity type semiconductor layer formed on the back side of the substrate, a first electrode layer formed on a part of the first conductivity type semiconductor layer, a second electrode layer formed on a part of the second conductivity type semiconductor layer, and an optical adjustment layer formed on the first conductivity type semiconductor layer excluding the first electrode layer on the light-receiving surface side of the substrate, wherein the radius of curvature of the top portion of the uneven structure at least a part of the peripheral edge on the light-receiving surface side is greater than the radius of curvature of the top portion of the uneven structure in the central part on the light-receiving surface side, the uneven structure of the substrate is reflected on the light-receiving surface of the solar cell, and the radius of curvature of the top portion of the uneven structure at least a part of the peripheral edge on the light-receiving surface side is greater than the radius of curvature of the top portion of the uneven structure in the central part on the light-receiving surface side.

[0010] Furthermore, in the solar cell module according to the present invention, the above-mentioned solar cells are arranged in a two-dimensional manner.

[0011] Furthermore, the method for manufacturing a solar cell according to the present invention is the method for manufacturing a solar cell described above, wherein in the step of forming an uneven structure on the light-receiving surface side of the crystalline silicon substrate, the flow rate of the etching solution in at least a part of the peripheral portion on the light-receiving surface side is controlled to be faster than the flow rate of the etching solution in the central portion on the light-receiving surface side. [Effects of the Invention]

[0012] According to the present invention, color unevenness of the light-receiving surface of individual solar cells can be reduced in modularization. [Brief explanation of the drawing]

[0013] [Figure 1] This is a view of the solar cell module according to this embodiment, seen from the light-receiving surface side. [Figure 2] This is a view of the solar cell according to this embodiment, seen from the light-receiving surface side. [Figure 3] This is a view of the solar cell according to this embodiment, seen from the back side. [Figure 4] Figures 2 and 3 show cross-sectional views of solar cells. [Figure 5] Figure 2 is a cross-sectional view showing the uneven structure in the central part of the light-receiving surface of the substrate. [Figure 6] Figure 2 is a cross-sectional view showing the uneven structure of the peripheral edge on the light-receiving surface side of the substrate. [Figure 7] Figure 3 is a cross-sectional view showing the uneven structure in the central part of the back side of the substrate. [Figure 8] Figure 3 is a cross-sectional view showing the uneven structure of the peripheral edge on the back side of the substrate. [Figure 9] Figures 2 and 3 show cross-sectional views illustrating the uneven structure on the side of the substrate. [Figure 10] This is a view of a modified solar cell module according to this embodiment, as seen from the light-receiving surface side. [Figure 11] This is a view of a modified solar cell according to this embodiment, seen from the light-receiving surface side. [Modes for carrying out the invention]

[0014] Hereinafter, an example of an embodiment of the present invention will be described with reference to the accompanying drawings. In each of the drawings, the same or corresponding parts will be denoted by the same reference numerals. Also, for the sake of convenience, hatching, member codes, etc. may be omitted, but in such cases, other drawings shall be referred to.

[0015] (Solar cell module) FIG. 1 is a view of the solar cell module according to the present embodiment as seen from the light-receiving surface side. The solar cell module 100 shown in FIG. 1 includes a plurality of solar cells 1 arranged two-dimensionally at equal intervals and spaced apart from each other. The solar cells 1 are connected in series and / or in parallel by known interconnects (not shown) such as tabs. The solar cells 1 are sealed by a light-receiving surface protection member, a back surface protection member, and a sealing material (not shown).

[0016] (Solar cell) FIG. 2 is a view of the solar cell according to the present embodiment as seen from the light-receiving surface side, FIG. 3 is a view of the solar cell according to the present embodiment as seen from the back surface side, and FIG. 4 is a cross-sectional view of the solar cell shown in FIGS. 2 and 3. The solar cell 1 shown in FIGS. 2 to 4 is a double-sided electrode type and illustrates a heterojunction type solar cell. Note that the solar cell according to the present embodiment is not limited to a heterojunction type solar cell, and can also be applied to various solar cells such as an aluminum back surface field (Aluminum Back Surface Field) type, a PERC (Passivated Emitter Rear Contact) type, a PERT (Passivated Emitter and Rear Totally diffused) type, a TOPCon (Tunnel Oxide Passivated Contact) type, etc. The solar cell 1 includes a crystalline silicon substrate 11 having two main surfaces.

[0017] As shown in Figure 4, the solar cell 1 comprises a crystalline silicon substrate 11 and, sequentially stacked on the light-receiving side of the substrate 11, a passivation layer 23, a first conductivity semiconductor layer 25, a first transparent electrode layer 27, a first electrode layer 28, and an optical adjustment layer 15. The solar cell 1 also comprises, sequentially stacked on the back side of the substrate 11, a passivation layer 33, a second conductivity semiconductor layer 35, a second transparent electrode layer 37, and a second electrode layer 38.

[0018] The substrate 11 is formed from a crystalline silicon material such as single-crystal silicon or polycrystalline silicon. The substrate 11 is, for example, an n-type substrate doped with an n-type dopant in a crystalline silicon material. Alternatively, the substrate 11 may be a p-type substrate doped with a p-type dopant in a crystalline silicon material. Examples of n-type dopants include phosphorus (P) and boron (B). The substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light-receiving surface and generates photocarriers (electrons and holes).

[0019] By using crystalline silicon as the material for the substrate 11, the dark current is relatively small, and relatively high output (stable output regardless of illuminance) can be obtained even when the intensity of incident light is low.

[0020] The substrate 11 has a pyramidal, finely uneven structure called a textured structure on the light-receiving surface side. This reduces the reflection of incident light on the light-receiving surface, improving the light confinement effect of the substrate 11.

[0021] Furthermore, the substrate 11 has a pyramidal, finely uneven structure called a textured structure on its back side. This increases the efficiency of recovering light that passes through the substrate 11 without being absorbed.

[0022] Furthermore, the substrate 11 has a pyramidal, finely textured structure on its side, known as a textured structure.

[0023] The passivation layer 23 is formed on the light-receiving side of the substrate 11. The passivation layer 33 is formed on the back side of the substrate 11. The passivation layers 23 and 33 are formed from a material mainly composed of, for example, intrinsic (type i) amorphous silicon material. The passivation layers 23 and 33 suppress the recombination of carriers generated on the substrate 11 and improve the carrier recovery efficiency.

[0024] The first conductive semiconductor layer 25 is formed on the passivation layer 23, that is, on the light-receiving side of the substrate 11. On the other hand, the second conductive semiconductor layer 35 is formed on the passivation layer 33, that is, on the back side of the substrate 11.

[0025] The first conductivity type semiconductor layer 25 is formed from, for example, amorphous silicon material. The first conductivity type semiconductor layer 25 is a p-type semiconductor layer in which an amorphous silicon material is doped with a p-type dopant (for example, the boron (B) mentioned above).

[0026] The second conductivity type semiconductor layer 35 is formed from, for example, an amorphous silicon material. The second conductivity type semiconductor layer 35 is an n-type semiconductor layer in which an n-type dopant (for example, phosphorus (P) as described above) is doped into an amorphous silicon material. Alternatively, the first conductivity type semiconductor layer 25 may be an n-type semiconductor layer and the second conductivity type semiconductor layer 35 may be a p-type semiconductor layer.

[0027] The first transparent electrode layer 27 is formed on the first conductivity type semiconductor layer 25, that is, on the light-receiving side of the substrate 11. On the other hand, the second transparent electrode layer 37 is formed on the second conductivity type semiconductor layer 35, that is, on the back side of the substrate 11. Note that the first transparent electrode layer 27 and the second transparent electrode layer 37 are not necessarily formed. The first transparent electrode layer 27 and the second transparent electrode layer 37 are formed from a transparent conductive material. Examples of transparent conductive materials include ITO (Indium Tin Oxide: a composite oxide of indium oxide and tin oxide).

[0028] The first electrode layer 28 is formed on a portion of the first conductive semiconductor layer 25 and the first transparent electrode layer 27, that is, on a portion of the light-receiving surface side of the substrate 11. On the other hand, the second electrode layer 38 is formed on a portion of the second conductive semiconductor layer 35 and the second transparent electrode layer 37, that is, on a portion of the back side of the substrate 11.

[0029] The first electrode layer 28 has a so-called comb-like shape and has a plurality of finger portions corresponding to the teeth of the comb and busbar portions corresponding to the support portions of the comb teeth. The busbar portions have a strip shape and extend in a first direction (X direction) along one side of the substrate 11. The finger portions have a strip shape and extend from the busbar portions in a second direction (Y direction) that intersects the first direction. The first electrode layer 28 may also be formed in a stripe shape.

[0030] Similarly, the second electrode layer 38 has a so-called comb-like shape and has a plurality of finger portions corresponding to the teeth of the comb and busbar portions corresponding to the support portions of the comb teeth. The busbar portions have a strip shape and extend in a first direction (X direction) along the other side of the substrate 11 opposite to one side. The finger portions have a strip shape and extend from the busbar portions in a second direction (Y direction). The second electrode layer 38 may also be formed in a stripe shape.

[0031] The first electrode layer 28 and the second electrode layer 38 are formed from a conductive paste material containing, for example, a metal powder such as silver.

[0032] The optical adjustment layer 15 is formed on the light-receiving side of the substrate 11, on the first conductivity type semiconductor layer 25 and the first transparent electrode layer 27, excluding the first electrode layer 28. That is, the optical adjustment layer 15 covers the areas of the first conductivity type semiconductor layer 25 and the first transparent electrode layer 27 where the first electrode layer 28 is not formed. The optical adjustment layer 15 functions as an anti-reflective layer to prevent reflection of incident light, and also functions as a protective layer to protect the light-receiving side of the substrate 11 and the passivation layer 13. The optical adjustment layer 15 is formed of an insulating material such as silicon oxide (SiO), silicon nitride (SiN), or a composite thereof such as silicon oxynitride (SiON). Alternatively, the optical adjustment layer 15 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide: a composite oxide of indium oxide and tin oxide).

[0033] Next, the uneven structure of the substrate 11 will be described with reference to Figures 2 to 9. Figure 5 is a cross-sectional view showing the uneven structure of the central part Af1 on the light-receiving surface side of the substrate 11 shown in Figure 2, and Figure 6 is a cross-sectional view showing the uneven structure of the peripheral part Af2 on the light-receiving surface side of the substrate 11 shown in Figure 2. Figure 7 is a cross-sectional view showing the uneven structure of the central part Ar1 on the back side of the substrate 11 shown in Figure 3, and Figure 8 is a cross-sectional view showing the uneven structure of the peripheral part Ar2 on the back side of the substrate 11 shown in Figure 3. Figure 9 is a cross-sectional view showing the uneven structure of the side surface As of the substrate 11 shown in Figures 2 and 3.

[0034] As shown in Figures 2, 5, and 6, in the substrate 11, the radius of curvature Rf2 of the top of the uneven structure at the peripheral Af2 on the light-receiving surface side is larger than the radius of curvature Rf1 of the top of the uneven structure at the central Af1 on the light-receiving surface side. The uneven structure of the substrate 11 is reflected on the light-receiving surface of the solar cell 1. As a result, in the solar cell 1, the radius of curvature of the top of the uneven structure at the peripheral Af2 on the light-receiving surface side is larger than the radius of curvature of the top of the uneven structure at the central Af1 on the light-receiving surface side.

[0035] Furthermore, in the passivation layer 23 and optical adjustment layer 15 of the solar cell 1, the film thickness of the peripheral portion Af2 on the light-receiving surface side is thinner than the film thickness of the central portion Af1 on the light-receiving surface side.

[0036] Furthermore, as shown in Figures 3, 7, and 8, in the substrate 11, the radius of curvature Rr2 of the top portion of the uneven structure of the peripheral portion Ar2 on the back side is larger than the radius of curvature Rr1 of the top portion of the uneven structure of the central portion Ar1 on the back side.

[0037] Furthermore, as shown in Figure 9, if Rs is the radius of curvature of the top portion of the uneven structure on the side As of the substrate 11, then these radii of curvature satisfy the following relationship. Rs>Rf2>Rf1>Rr2>Rr1

[0038] (Method of manufacturing solar cells) The manufacturing method for the solar cell 1 according to this embodiment, as shown in Figures 2 to 9, will be described below.

[0039] First, anisotropic etching is performed on the light-receiving side and the back side of the crystalline silicon substrate 11 to form a pyramidal, finely uneven structure called a textured structure (crystalline silicon substrate formation process). At this time, anisotropic etching is also performed on the sides of the crystalline silicon substrate 11, forming a pyramidal, finely uneven structure called a textured structure. Examples of etching solutions include alkaline solutions such as potassium hydroxide aqueous solution.

[0040] At this time, the flow rate of the etching solution at the peripheral Af2 on the light-receiving surface side is controlled to be faster than the flow rate of the etching solution at the central Af1 on the light-receiving surface side. Also, the flow rate of the etching solution at the peripheral Ar2 on the back side is controlled to be faster than the flow rate of the etching solution at the central Ar1 on the back side.

[0041] As a result, the radius of curvature Rf1 of the top of the uneven structure in the central part Af1 on the light-receiving surface, the radius of curvature Rf2 of the top of the uneven structure in the peripheral part Af2 on the light-receiving surface, the radius of curvature Rr1 of the top of the uneven structure in the central part Ar1 on the back side, the radius of curvature Rr2 of the top of the uneven structure in the peripheral part Ar2 on the back side, and the radius of curvature Rs of the top of the uneven structure on the side As side will satisfy the following relationship. Rs>Rf2>Rf1>Rr2>Rr1

[0042] Next, a passivation layer 23 and a first conductivity type semiconductor layer 25 are formed on the light-receiving side of the substrate 11, for example, using the CVD (chemical vapor deposition) method or the PVD (physical vapor deposition) method (semiconductor layer formation process). Also, a passivation layer 33 and a second conductivity type semiconductor layer 35 are formed on the back side of the substrate 11, for example, using the CVD method or the PVD method (semiconductor layer formation process).

[0043] Next, a first transparent electrode layer 27 is formed on the first conductivity type semiconductor layer 25 on the light-receiving side of the substrate 11, for example, using a CVD method or a PVD method (transparent electrode layer formation step). Also, a second transparent electrode layer 37 is formed on the second conductivity type semiconductor layer 35 on the back side of the substrate 11, for example, using a CVD method or a PVD method (transparent electrode layer formation step).

[0044] Next, a first electrode layer 28 is formed on the first conductivity semiconductor layer 25 and the first transparent electrode layer 27 on the light-receiving side of the substrate 11, for example, using a pattern printing method or a coating method (electrode layer formation step). Also, a second electrode layer 38 is formed on the second conductivity semiconductor layer 35 and the second transparent electrode layer 37 on the back side of the substrate 11, for example, using a pattern printing method or a coating method (electrode layer formation step).

[0045] Next, an optical adjustment layer 15 is formed on the first conductivity type semiconductor layer 25 and the first transparent electrode layer 27 on the light-receiving surface side of the substrate 11, excluding the first electrode layer 28, using, for example, a CVD method or a PVD method (optical adjustment layer formation step).

[0046] The formation order of the passivation layers 23, 33, the first conductivity type semiconductor layer 25 and the second conductivity type semiconductor layer 35, the first transparent electrode layer 27 and the second transparent electrode layer 37, the first electrode layer 28 and the second electrode layer 38, and the optical adjustment layer 15 is not limited.

[0047] The light-receiving surface of the solar cell 1 reflects the uneven structure of the substrate 11. In the solar cell 1, the radius of curvature of the top of the uneven structure of the peripheral Af2 on the light-receiving surface side is greater than the radius of curvature of the top of the uneven structure of the central Af1 on the light-receiving surface side. Furthermore, in the passivation layer 23, the first conductive semiconductor layer 25, the first transparent electrode layer 27, and the optical adjustment layer 15 of the solar cell 1, the film thickness of the peripheral Af2 on the light-receiving surface side is thinner than the film thickness of the central Af1 on the light-receiving surface side. Through the above steps, the double-sided electrode type solar cell 1 according to this embodiment, as shown in Figures 2 to 9, is completed.

[0048] As described above, according to the solar cell 1 of this embodiment, in the substrate 11, the radius of curvature Rf2 of the top part of the uneven structure of the peripheral Af2 on the light-receiving surface side is larger than the radius of curvature Rf1 of the top part of the uneven structure of the central Af1 on the light-receiving surface side. The uneven structure of the substrate 11 is reflected on the light-receiving surface of the solar cell 1, and in the solar cell 1, the radius of curvature of the top part of the uneven structure of the peripheral Af2 on the light-receiving surface side is larger than the radius of curvature of the top part of the uneven structure of the central Af1 on the light-receiving surface side.

[0049] In this way, by controlling the curvature radius Rf2 of the top portion of the uneven structure of the peripheral edge Af2 on the light-receiving surface side to be larger, the reflection of light at the top portion of the uneven structure of the peripheral edge Af2 on the light-receiving surface side increases, making it appear, for example, white. In this way, by controlling the texture shape of the peripheral edge Af2 on the light-receiving surface side and deliberately making the peripheral edge Af2 on the light-receiving surface side of the solar cell 1 more prominent, the solar cell 1 can be seen three-dimensionally within the solar cell module 100, and the color distribution inside the solar cell module 100 becomes less noticeable.

[0050] Furthermore, in the solar cell 1 of this embodiment, the film thickness of the peripheral portion Af2 on the light-receiving surface side of the optical adjustment layer 15 is thinner than the film thickness of the central portion Af1 on the light-receiving surface side. When the film thickness of the peripheral portion Af2 on the light-receiving surface side is thinned in this way, the reflection of light at the top of the uneven structure of the peripheral portion Af2 on the light-receiving surface side increases, making it appear, for example, white.

[0051] In this way, by controlling the texture shape of the peripheral Af2 on the light-receiving surface side, as well as the film thickness of the optical adjustment layer 15, the peripheral Af2 on the light-receiving surface side of the solar cell 1 is deliberately made more prominent, allowing the solar cell 1 to be viewed three-dimensionally within the solar cell module 100, and making the color distribution inside the solar cell module 100 less noticeable.

[0052] However, if an uneven structure is formed on the light-receiving surface and / or back surface of the substrate 11, chipping may occur at the edges of the substrate 11.

[0053] In this regard, according to the solar cell 1 of this embodiment, in the substrate 11, the radius of curvature Rf2 of the top portion of the uneven structure of the peripheral portion Af2 on the light-receiving surface side is larger than the radius of curvature Rf1 of the top portion of the uneven structure of the central portion Af1 on the light-receiving surface side. Also, in the substrate 11, the radius of curvature Rr2 of the top portion of the uneven structure of the peripheral portion Ar2 on the back side is larger than the radius of curvature Rr1 of the top portion of the uneven structure of the central portion Ar1 on the back side. Furthermore, these radii of curvature satisfy the following relationship. Rf2>Rf1>Rr2>Rr1

[0054] In this way, by controlling the radius of curvature Rf2 of the top portion of the uneven structure on the peripheral edge Af2 on the light-receiving surface side to be larger, chipping at the edges of the substrate 11 can be reduced. Therefore, the productivity of the solar cell 1 can be improved. Furthermore, by controlling the radius of curvature Rr2 of the top portion of the uneven structure on the peripheral edge Ar2 on the back side to be larger, chipping at the edges of the substrate 11 can be reduced. As a result, the productivity of the solar cell 1 can be improved.

[0055] In anisotropic etching, a textured surface is formed not only on the light-receiving surface and the back surface of the substrate 11, but also on the sides (end surfaces). Of the edges of the substrate 11 (periphery of the light-receiving surface, periphery of the back surface, and sides), chipping is more likely to occur on the textured surface of the sides.

[0056] In this regard, according to the solar cell 1 of this embodiment, if Rs is the radius of curvature of the top portion of the uneven structure on the side surface of the substrate 11, then these radii of curvature satisfy the following relationship. Rs>Rf2>Rf1>Rr2>Rr1

[0057] In this way, by controlling the curvature radius Rs of the top portion of the uneven structure on the side to be large, chipping at the edges of the substrate 11 can be reduced. Therefore, the productivity of the solar cell 1 can be improved.

[0058] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications and variations are possible. For example, the embodiments described above illustrate a form in which a large-format semiconductor substrate (wafer) of a specified size (e.g., a 6-inch semi-square shape) is used as is. However, the present invention is not limited thereto, and as shown in Figures 10 and 11, a form in which a large-format semiconductor substrate of a specified size is cut in half to use solar cells may be used, or a form in which a large-format semiconductor substrate of a specified size is cut into three or more pieces to use solar cells.

[0059] In this case, in the substrate 11, the radius of curvature Rf2 of the top portion of at least a part of the uneven structure on the peripheral Af2 on the light-receiving surface side should be larger than the radius of curvature Rf1 of the top portion of the uneven structure on the central Af1 on the light-receiving surface side. Similarly, in the solar cell 1, the radius of curvature of the top portion of the uneven structure on at least a part of the peripheral Af2 on the light-receiving surface side should be larger than the radius of curvature of the top portion of the uneven structure on the central Af1 on the light-receiving surface side. Furthermore, in the optical adjustment layer 15, the film thickness of at least a part of the peripheral Af2 on the light-receiving surface side should be thinner than the film thickness of the central Af1 on the light-receiving surface side.

[0060] Furthermore, in the substrate 11, the radius of curvature Rr2 of the top portion of the uneven structure on at least a part of the peripheral portion Ar2 on the back side should be greater than the radius of curvature Rr1 of the top portion of the uneven structure on the central portion Ar1 on the back side. In addition, these radii of curvature should satisfy the following relationship. Rs>Rf2>Rf1>Rr2>Rr1 [Explanation of Symbols]

[0061] 1. Solar cell 11. Crystalline silicon substrate 15 Optical adjustment layer 23,33 Passivation layer 25 First Conductivity Semiconductor Layer 27 First transparent electrode layer 28 1st electrode layer 35 Second Conductivity Semiconductor Layer 37 Second transparent electrode layer 38 Second electrode layer 100 solar modules

Claims

1. A crystalline silicon substrate having an uneven surface structure on the light-receiving surface side, A first conductivity type semiconductor layer formed on the light-receiving surface side of the substrate, A second conductive semiconductor layer formed on the back side of the substrate, A first electrode layer formed on a portion of the first conductivity type semiconductor layer, A second electrode layer formed on a portion of the second conductivity semiconductor layer, On the light-receiving surface side of the substrate, an optical adjustment layer is formed on the first conductivity type semiconductor layer excluding the first electrode layer, A solar cell equipped with, In the substrate, the radius of curvature of the top portion of the uneven structure at at least a part of the peripheral edge on the light-receiving surface side is greater than the radius of curvature of the top portion of the uneven structure in the central part on the light-receiving surface side. The light-receiving surface of the solar cell reflects the uneven structure of the substrate. In the solar cell, the radius of curvature of the top portion of the uneven structure at at least a part of the peripheral edge on the light-receiving surface side is greater than the radius of curvature of the top portion of the uneven structure in the central part on the light-receiving surface side. Solar cell.

2. The solar cell according to claim 1, wherein the optical adjustment layer has a film thickness of at least a portion of the peripheral edge on the light-receiving surface side that is thinner than the film thickness of the central portion on the light-receiving surface side.

3. The substrate has an uneven structure on its back side, The solar cell according to claim 1 or 2, wherein the radius of curvature of the top portion of the uneven structure at at least a part of the peripheral edge on the back side of the substrate is greater than the radius of curvature of the top portion of the uneven structure in the central part on the back side.

4. In the substrate, if Rf1 is the radius of curvature of the top portion of the uneven structure in the central part of the light-receiving surface, Rf2 is the radius of curvature of the top portion of at least a part of the uneven structure in the peripheral part of the light-receiving surface, Rr1 is the radius of curvature of the top portion of the uneven structure in the central part of the back surface, and Rr2 is the radius of curvature of the top portion of at least a part of the uneven structure in the peripheral part of the back surface, then these radii of curvature satisfy the following relationship: Rf2>Rf1>Rr2>Rr1 The solar cell according to claim 3.

5. The substrate has an uneven surface on its side, In the aforementioned substrate, if Rs is the radius of curvature of the top portion of the uneven structure on the side surface, then these radii of curvature satisfy the following relationship: Rs>Rf2>Rf1>Rr2>Rr1 The solar cell according to claim 4.

6. A solar cell module in which the solar cells according to claim 1 or 2 are arranged in a two-dimensional manner.

7. A method for manufacturing a solar cell according to claim 1 or 2, In the process of forming an uneven structure on the light-receiving surface side of the crystalline silicon substrate, the flow rate of the etching solution in at least a portion of the peripheral edge on the light-receiving surface side is controlled to be faster than the flow rate of the etching solution in the central part of the light-receiving surface side. A method for manufacturing solar cells.

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