Solar cell with junction retracted from cut edge

Abstract

The present invention provides a method for manufacturing a solar cell having a junction retracted from a cut edge, and the resulting solar cell. In one example, the solar cell includes a substrate having a light receiving surface, a back surface, and side walls. An emitter region is in the substrate, and the emitter region is at the light receiving surface of the substrate. The emitter region has a side wall that is laterally retracted from the side wall of the substrate. A passivation layer is on the side wall of the emitter region.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Application No. 16 / 381,482, filed on April 11, 2019, which claims priority to U.S. Provisional Patent Application No. 62 / 658,443, filed earlier on April 16, 2018, the entire contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] Embodiments of the present disclosure are in the field of renewable energy, and in particular, relate to methods of manufacturing solar cells having junctions retracted from cut edges, and the resulting solar cells. Background Art

[0004] Photovoltaic cells (often referred to as solar cells) are well-known devices for converting solar radiation directly into electrical energy. Generally speaking, solar cells are manufactured on semiconductor wafers or substrates using semiconductor processing techniques to form pn junctions near the surface of the substrate. Solar radiation that impinges on the substrate surface and enters the substrate forms electron and hole pairs in the bulk of the substrate. The electron and hole pairs migrate to p-doped and n-doped regions in the substrate, thereby generating a voltage difference between the doped regions. The doped regions are connected to conductive regions on the solar cell to direct current from the cell to an external circuit coupled thereto.

[0005] Electrical conversion efficiency is an important characteristic of a solar cell because it is directly related to the solar cell's ability to generate electricity; higher efficiency provides added value to the end customer; and, all other things being equal, higher efficiency also reduces the manufacturing cost per watt. Similarly, simplified manufacturing methods can also reduce manufacturing costs by reducing the unit cost of production. Therefore, techniques for improving solar cell efficiency and techniques for simplifying the manufacture of solar cells are generally needed. Some embodiments of the present disclosure allow for improving solar cell conversion efficiency and / or reducing manufacturing costs by providing new processes for manufacturing solar cell structures. Some embodiments of the present disclosure allow for improving solar cell efficiency and / or reducing manufacturing costs by providing novel solar cell structures.

[0006] BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A cross-sectional view of a solar cell having an emitter region including unprotected edges is shown.

[0008] Figure 2A A cross-sectional view of a solar cell having an emitter region including retracted protected edges according to one embodiment of the present disclosure is shown.

[0009] Figure 2B A cross-sectional view of a solar cell having an emitter region including retracted protected edges according to another embodiment of the present disclosure is shown.

[0010] Figure 2C A cross-sectional view of a solar cell having an emitter region including retracted protected edges according to another embodiment of the present disclosure is shown.

[0011] Figure 3 A plan view of forming a solar cell having an emitter region including retracted protected edges according to one embodiment of the present disclosure is shown.

[0012] Figure 4 A schematic cross-sectional view of a string of solar cells connected in series and arranged in a shingled manner is shown, wherein ends of adjacent solar cells overlap to form a shingled super cell according to one embodiment of the present disclosure.

[0013] Figure 5 is a diagram of the front (sun-side) surface and front surface metallization pattern of an illustrative rectangular solar cell that may be used to form a shingled super cell according to another embodiment of the disclosure.

[0014] Fig. 6A Schematic diagram showing an exemplary method by which a pseudo-square silicon solar cell of standard size and shape may be separated (e.g., diced or divided) into two rectangular solar cells of different lengths that may be used to form a shingled super cell, in accordance with another embodiment of the disclosure.

[0015] Figure 6B and 6C A schematic diagram showing another exemplary method according to an embodiment of the present disclosure, by which a pseudo-square silicon solar cell can be separated into rectangular solar cells.

[0016] Fig.6D and 6E A schematic diagram showing an exemplary method according to an embodiment of the present disclosure, by which a square silicon solar cell can be separated into rectangular solar cells.

[0017] Figure 7 A fragmentary view of the front surface of an exemplary rectangular super cell according to an embodiment of the disclosure is shown, the rectangular super cell including Figure 5 The rectangular solar cell shown in FIG. Figure 4 Arrange in the overlapping manner shown.

[0018] Fig. 8AA schematic diagram showing an example rectangular solar module comprising multiple stacked rectangular super cells, wherein the length of the long side of each super cell is approximately half the length of the short side of the module. According to one embodiment of the disclosure, pairs of super cells are arranged end-to-end in rows with the long sides of the super cells parallel to the short sides of the module.

[0019] Figure 8B A schematic diagram showing another example rectangular solar module comprising multiple stacked rectangular super cells, wherein the length of the long side of each super cell is approximately equal to the length of the short side of the module. According to one embodiment of the disclosure, the super cells are arranged with their long sides parallel to the short sides of the module.

[0020] Figure 8C A schematic diagram showing another example rectangular solar module comprising multiple stacked rectangular super cells with the length of the long side of each super cell approximately equal to the length of the long side of the module. According to one embodiment of the disclosure, the super cells are arranged with their long sides parallel to the sides of the module.

[0021] Fig.8D A schematic diagram showing an example rectangular solar module comprising multiple shingled rectangular super cells, with the length of the long side of each super cell approximately equal to half the length of the long side of the module. According to one embodiment of the disclosure, pairs of super cells are arranged end-to-end in rows with the long sides of the super cells parallel to the long sides of the module.

[0022] Fig. 8E A plan view showing a solar cell module including half-cut cells according to one embodiment of the present disclosure.

[0023] Figure 8F An embodiment according to the present disclosure is shown Fig. 8E An enlarged view of a portion of a solar cell module.

[0024] Figure 8G A plan view of a solar cell module including a vertical shingled strand with a rectangular strip arrangement is shown according to one embodiment of the present disclosure.

[0025] Figure 8H A plan view of a solar cell module including a vertical strand with a shingled chamfered cell arrangement is shown according to one embodiment of the present disclosure.

[0026] Fig.8I A plan view of a solar cell module including a vertical strand with shingled cells and a centerline arrangement according to one embodiment of the present disclosure is shown.

[0027] Fig. 9An example arrangement of three rows of super cells is shown, interconnected with flexible electrical interconnects to connect the super cells in series with each other within each row and to connect the rows parallel to each other. These may be Fig.8D Three rows of solar modules.

[0028] Fig. 10A An embodiment according to the present disclosure is shown Fig.8D Details in A: Fig.8D Cross-sectional view of an exemplary solar module of FIG. 1 showing cross-sectional details of flexible electrical interconnects bonded to back surface terminal contacts of rows of super cells.

[0029] Fig. 10B An embodiment according to the present disclosure is shown Fig.8D Details in C: Fig.8D Cross-sectional view of an exemplary solar module showing cross-sectional details of flexible electrical interconnects bonded to front (sun-side) surface terminal contacts of a row of super cells.

[0030] Fig. 10C An embodiment according to the present disclosure is shown Fig.8D Details in B: Fig.8D Cross-sectional view of an exemplary solar module showing cross-sectional detail of a flexible interconnect arranged to interconnect two super cells in series in a row.

[0031] Fig.11 and 12 A simplified cross-sectional view of an array is shown according to one embodiment of the present disclosure, wherein the array comprises a plurality of modules assembled in a stacked arrangement.

[0032] Fig.13 The flowchart shows various operations in a method for manufacturing a solar cell according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] The following detailed description is merely exemplary in nature and is not intended to limit the embodiments of the subject matter or the application and use of such embodiments. As used herein, the word "exemplary" means "used as an example, instance or illustration". Any embodiment described herein as exemplary is not necessarily understood to be preferred or advantageous over other embodiments. In addition, it is not intended to be bound by any express or implied theory presented in the aforementioned technical field, background technology, summary of the invention or the following detailed description.

[0034] This specification contains references to "one embodiment" or "an embodiment." The appearance of the phrase "in one embodiment" or "in an embodiment" does not necessarily refer to the same embodiment. The particular features, structures, or characteristics may be combined in any suitable manner consistent with the present disclosure.

[0035] Terminology. The following paragraphs provide definitions and / or context for terms found in this disclosure (including the appended claims):

[0036] As used herein, "region" or "portion" may be used to describe a discrete area, volume, portion, or location of an object or material having definable characteristics but not necessarily fixed boundaries.

[0037] "Comprising". This term is open ended. As used in the appended claims, this term does not exclude other structures or steps.

[0038] "Configured to". Various units or components may be described or stated as being "configured to" perform one or more tasks. In such contexts, "configured to" is used to imply structure by indicating that the unit / component includes structure to perform one or more of those tasks during operation. Thus, the unit / component may be said to be configured to perform a task even when the specified unit / component is not currently in operation (e.g., not turned on / activated). Reciting a unit / circuit / component as "configured to" perform one or more tasks is expressly intended not to invoke 35 USC §112, sixth paragraph, with respect to that unit / component.

[0039] "First", "second", etc., as used herein, these terms are used as labels for the nouns that follow them, and do not imply any type of order (e.g., spatial, temporal, logical, etc.). For example, referring to a "first" solar cell does not necessarily imply that the solar cell is the first solar cell in a sequence; rather, the term "first" is used to distinguish the solar cell from another solar cell (e.g., a "second" solar cell).

[0040] "Coupled" - The following description refers to elements or nodes or structural features being "coupled" together. As used herein, unless expressly stated otherwise, "coupled" means that one element / node / feature is directly or indirectly connected to (or directly or indirectly communicates with) another element / node / feature, and not necessarily mechanically.

[0041] In addition, certain terms may be used in the following description for reference purposes only and are therefore not intended to be limiting. For example, terms such as "upper," "lower," "above," and "below" refer to directions in the drawings for which reference is provided. Terms such as "front," "back," "rear," "side," "outer," and "inner" describe the orientation and / or position of certain portions of a component within a consistent but arbitrary reference system that can be clearly understood by reference to the text describing the component in question and the associated drawings. Such terms may include the words specifically mentioned above, their derivatives, and words of similar meaning.

[0042] "Prevent" - As used herein, prevent is used to describe reducing or minimizing an effect. When a component or feature is described as preventing an action, movement, or condition, it may completely and utterly prevent a result, consequence, or future state. Additionally, "prevent" may also refer to reducing or minimizing a consequence, property, and / or effect that might occur. Thus, when a component, element, or feature is referred to as preventing a result or state, it does not necessarily completely prevent or eliminate that result or state.

[0043] Methods for making solar cells having junctions retracted from cut edges, and the resulting solar cells, are described herein. In the following description, many specific details, such as specific process flow operations, are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that embodiments of the present disclosure may be practiced without these specific details. In other examples, well-known manufacturing techniques, such as lithography and patterning techniques, are not described in detail to avoid unnecessarily obscuring the embodiments of the present disclosure. In addition, it should be understood that the various embodiments shown in the figures are exemplary displays and are not necessarily drawn to scale.

[0044] The present invention discloses a solar cell. In one embodiment, the solar cell includes a substrate having a light receiving surface, a back surface and a side wall. An emitter region in the substrate is at the light receiving surface of the substrate. The emitter region has a side wall that is laterally retracted from the side wall of the substrate. A passivation layer is on the side wall of the emitter region.

[0045] Also disclosed herein is a method for manufacturing a solar cell. In one embodiment, a method for manufacturing a solar cell includes forming an emitter region in a substrate, the emitter region being at a light receiving surface of the substrate. Forming a separation region or groove in the emitter region. Forming a passivation layer on the light receiving surface of the substrate and in the groove. Cutting the substrate to form a solar cell having a sidewall and an emitter region, the emitter region having a sidewall that is laterally retracted from the sidewall of the solar cell.

[0046] One or more embodiments described herein relate to a low-cost industrial solution for separating solar cell junctions from cut edges. Embodiments for manufacturing shingled cells may be implemented. The methods described herein may be used to implement front contact solar cell manufacturing or back contact solar cell manufacturing, which methods cut and divide cells into smaller cells for module assembly, such as half-cut cell modules.

[0047] To provide context, a solar cell string can be formed by cutting cells (such as P-type cells) and then stacking the cut cells together. In this process, non-passivated cut edges and exposed junctions can be formed. Such non-passivated cut edges and / or exposed junctions can cause 2% to 3% initial power loss and reduce performance under low lighting conditions.

[0048] According to one or more embodiments of the present disclosure, an industrially feasible method is described to form a passivated separation region or trench that isolates the junction edge of the front side from the exposed silicon edge of the cut. Silicon thermal oxidation plasma enhanced chemical vapor deposition of silicon nitride can then be performed to passivate the trench and junction edge. In one embodiment, the leakage current on the exposed junction is significantly reduced, thereby improving efficiency and performance under low light conditions.

[0049] To provide further context, a shingled process can show a potential for about 10% relative efficiency improvement compared to a high efficiency module process using the same cell. However, in practice, the relative efficiency of such shingled cells can only be improved by about 6% to 7% due to power losses caused by the cut edges. It should be understood that there can be two main issues with the cut edges: (1) exposed junctions, and (2) non-passivated exposed silicon edges, which may be accompanied by some laser damage. Without being bound by theory, it should be understood that the exposed junctions contribute about two-thirds of the losses, while the second issue contributes about one-third of the losses. The embodiments described herein can be viewed as primarily addressing issue (1), which can be critical for performance under low lighting conditions.

[0050] To provide an illustrative context, Figure 1 A cross-sectional view of a solar cell having an emitter region including unprotected edges is shown.

[0051] refer to Figure 1 , the solar cell 100 includes a p-type substrate 102 having a light receiving surface, a back surface, and sidewalls. A lightly doped emitter region 116 in the substrate 102 is at the light receiving surface of the substrate 102. The emitter region 116 has sidewalls that are aligned (or flush) with the sidewalls of the substrate 102. A passivation layer 118 is on the light receiving surface of the substrate.

[0052] Reference again Figure 1 , the conductive contact 120 is electrically connected to the heavily doped region 106 having n-type conductivity within the emitter region 116. The above case is a selective emitter method. For a uniform emitter, 116 and 106 have the same doping. The conductive contact 120 is formed by screen printing a silver paste and firing it in a furnace through the passivation layer 118 to form an electrical contact. The solar cell 100 further includes a p-type doped region 104 at the back surface of the substrate 102. The conductive contact 110 is electrically connected to the p-type doped region 104 at the back surface of the substrate 102 through, for example, an opening in the bottom passivation and capping layer 108 such as AlOx / SiNy. Region 110 is screen printed Al paste, and the paste reacts with the silicon in region 102 to form the p-type doped region 104.

[0053] Reference again Figure 1 , the sidewall of the solar cell 100 may include one or more of a laser cut edge 112, a non-passivated edge 114, and an exposed junction 122. Embodiments of the present disclosure may be implemented to address issues associated with the exposed junction 122. Implementations may involve improving cell efficiency and performance under low light conditions, and the cost may be relatively low.

[0054] It should be understood that the stacked solar cell series connection may include selective emitter processing. The embodiments described herein may introduce additional process operations to open a solid doping layer such as a phosphosilicate glass (PSG) layer in the same operation of selective emitter fabrication by doping the PSG layer. Opening the solid doping layer can remove a portion of the formed emitter region using laser ablation or screen printing or inkjet etching paste patterning operations. The removed portion of the emitter region can then be passivated in a subsequent process operation, such as by forming a passivation layer. The passivation layer may be a passivating material or an insulating material, such as but not limited to SiOx, SiNx, TiOx, a combination thereof, a single anti-reflective coating (ARC) or a multi-layer ARC. When the tile is formed in the subsequent laser slicing and cutting process, the cutting performed must occur within or near the area defined by the groove. In one embodiment, a complete separation area or a complete groove method is used. In another embodiment, a partial separation area or a partial groove method is used.

[0055] As an example of a solar cell with a passivated junction, Figure 2A A cross-sectional view of a solar cell having an emitter region including retracted protected edges according to one embodiment of the present disclosure is shown.

[0056] refer to Figure 2A , the solar cell 200A includes a substrate 202A having a light receiving surface, a back surface and side walls. The emitter region 216A in the substrate 202A is at the light receiving surface of the substrate 202A. The emitter region 216A has a side wall that is laterally retracted from the side wall of the substrate 202A. The passivation layer 224A / 226A is on the side wall of the emitter region 216A. According to one embodiment, as shown in the figure, the passivation layer 224A / 226A is in a corresponding recessed portion between the corresponding side wall of the emitter region 216A and the corresponding side wall of the substrate 202A. In one such embodiment, as shown in the figure, the corresponding edge of the passivation layer 224A / 226A is vertically aligned with the corresponding side wall of the substrate 202A.

[0057] refer to Figure 2APart (B), solar cell 250A includes substrate 252A, which has a light receiving surface, a back surface and side walls. The emitter region 266A in substrate 252A is at the light receiving surface of substrate 252A. The emitter region 266A has a sidewall that is laterally retracted from the sidewall of substrate 252A. Passivation layer 274A / 276A is on the sidewall of emitter region 266A. According to one embodiment, as shown in the figure, passivation layer 274A / 276A is in a corresponding groove between the corresponding sidewall of emitter region 266A and the corresponding sidewall of substrate 252A. In one such embodiment, as shown in the figure, the isolated emitter region portion 275A / 277A remains as a passivation layer 274A / 276A that is laterally adjacent to the periphery of solar cell 250A.

[0058] Reference Figure 2A In the portions (A) and (B) of the emitter region 216A or 266A, the passivation layer 218A or 268A is respectively on the light receiving surface of the substrate 202A or 252A. The passivation layer 224A / 226A or 274A / 276A on the sidewall of the emitter region 216A or 266A is respectively continuous with the passivation layer 218A or 268A on the light receiving surface of the substrate 202A or 252A. In one embodiment, the passivation layer 216A / 224A / 226A or 266A / 274A / 276A includes silicon oxide (SiOx) or silicon nitride (SiNx) or a combination of a layer of silicon oxide (SiOx) and a layer of silicon nitride (SiNx).

[0059] Reference again Figure 2A In the embodiment of the present invention, the emitter region 216A or 266A includes a dopant of a conductivity type at a concentration, and the solar cell further includes a dopant region 206A or 256A of the conductivity type within the emitter region 216A or 266A, respectively. In one embodiment, the dopant region 206A or 256A of the conductivity type has a concentration of the dopant of the conductivity type that is higher than the concentration of the dopant of the conductivity type of the emitter region 216A or 266A, respectively. In one embodiment, the conductivity type is n-type, and the dopant is selected from the group consisting of: phosphorus dopant and arsenic dopant.

[0060] Reference again Figure 2A In portions (A) and (B) of the emitter region 216A or 266A, the conductive contact 220A or 270A is electrically connected to the conductive type dopant region 206A or 256A, respectively, within the emitter region 216A or 266A. In one such embodiment, as shown, the conductive contact 220A or 270A is formed by screen printing Ag paste and firing through the passivation layer 218A or 268A, respectively, which is on the light receiving surface of the substrate 202A or 252A, respectively.

[0061] In one embodiment, the conductive contact 220A or 270A comprises silver. In one such embodiment, the conductive contact 220A or 270A is formed using a conductive paste such as a silver-based conductive paste. In a specific such embodiment, the conductive paste comprises silver (Ag) powder and a solvent or resin. In one embodiment, the conductive paste further comprises glass frit. In another embodiment, the conductive paste does not comprise glass frit. In either case, in one embodiment, the silver paste may be fired or sintered onto the passivation layer 218A or 268A, respectively, to form the conductive contact 220A or 270A, respectively.

[0062] Reference again Figure 2A (A) and (B), in one embodiment, the substrate 202A or 252A is a p-type single crystal silicon substrate. In one embodiment, the light receiving surface of the substrate 202A or 252A is textured to provide a textured light receiving surface. In a specific embodiment, the light receiving surface of the substrate 202A or 252A is textured using a hydroxide-based wet etchant.

[0063] Reference again Figure 2A In one embodiment, the emitter region 216A or 266A includes an n-type dopant, and the solar cell 200A or 250A further includes a heavily doped p-type dopant region 204A or 254A on the back surface of the substrate 202A or 252A, respectively. In one embodiment, the p-type dopant is an aluminum dopant or a boron dopant from a new generation paste.

[0064] Reference again Figure 2A In the portions (A) and (B) of the substrate 202A or 252A, the conductive contacts 210A or 260A are electrically connected to the p-type dopant region 204A or 254A of the back surface of the substrate 202A or 252A, respectively. In one embodiment, the conductive contacts 210A or 260A are screen-printed and fired Al, but may not be limited thereto. The conductive contacts 210A or 260A are formed by screen-printing and firing Al paste through openings in the bottom passivation and capping layer 208A or 258A, respectively, which are on the back surface of the substrate 202A or 252A, respectively. In one embodiment, the bottom passivation and capping layer 208A or 258A is a silicon nitride layer or an amorphous silicon layer.

[0065] Therefore, refer again Figure 2A In parts (A) and (B), according to one or more embodiments of the present disclosure, the isolation trench scheme includes manufacturing a complete trench or a partial trench, the latter of which can be associated with a faster processing time. It should be understood that in any scheme, the metal can be kept away from the trench to avoid shunting.

[0066] As another example of a solar cell with a passivated junction, Figure 2B A cross-sectional view of a solar cell having an emitter region including retracted protected edges according to another embodiment of the present disclosure is shown.

[0067] refer to Figure 2B 2B, the solar cell 200B includes a substrate 202B having a light receiving surface, a back surface and a side wall. The emitter region 216B on the substrate 202B is at the light receiving surface of the substrate 202B. The emitter region 216B has a side wall that is laterally retracted from the side wall of the substrate 202B. The passivation layer 226B is on the side wall of the emitter region 216B. According to one embodiment, as shown in the figure, the passivation layer 226B is in a corresponding recessed portion between the corresponding side wall of the emitter region 216B and the corresponding side wall of the substrate 202B. In one such embodiment, as shown in the figure, the corresponding edge of the passivation layer 226B is vertically aligned with the corresponding side wall of the substrate 202B.

[0068] refer to Figure 2B Part (B), solar cell 250B includes substrate 252B, which has a light receiving surface, a back surface and side walls. The emitter region 266B in substrate 252B is at the light receiving surface of substrate 252B. The emitter region 266B has a sidewall that is laterally retracted from the sidewall of substrate 252B. The passivation layer 276B is on the sidewall of the emitter region 266B. According to one embodiment, as shown in the figure, the passivation layer 276B is in a corresponding groove between the corresponding sidewall of the emitter region 266B and the corresponding sidewall of the substrate 252B. In one such embodiment, as shown in the figure, the isolated emitter region portion remains as a passivation layer 276B that is laterally adjacent to the periphery of the solar cell 250B.

[0069] Reference Figure 2B In the parts (A) and (B) of the emitter region 216B or 266B, the passivation layer 218B or 268B is respectively on the light receiving surface of the substrate 202B or 252B. The passivation layer 226B or 276B on the sidewall of the emitter region 216B or 266B is respectively continuous with the passivation layer 218B or 268B on the light receiving surface of the substrate 202B or 252B. In one embodiment, the passivation layer 216B / 226B or 266B / 276B includes silicon oxide (SiOx) or silicon nitride (SiNx) or aluminum oxide (AlOx) or a combination of two or more of a layer of silicon oxide (SiOx), a layer of silicon nitride (SiNx) and / or a layer of aluminum oxide (AlOx).

[0070] Reference again Figure 2BIn portions (A) and (B) of the embodiment of the present invention, conductive contact 220B or 270B is electrically connected to a conductive type dopant region 206B or 256B within emitter region 216B or 266B, respectively. Conductive contact 210B or 260B is electrically connected to region 204B or 254B on the back surface of substrate 202B or 252B, respectively, having a conductivity opposite to that of 206B and 266B.

[0071] As another example of a solar cell with a passivated junction, Figure 2C A cross-sectional view of a solar cell having an emitter region including retracted protected edges according to one embodiment of the present disclosure is shown.

[0072] refer to Figure 2C In part (A), solar cell 200C includes substrate 202C having a first (e.g., top) and a second (e.g., bottom) light receiving surface and sidewalls. Emitter layer 216C1 on intrinsic layer 215C of substrate 202C is at the first light receiving surface of substrate 202C. Emitter region 216C1 has a sidewall that is laterally retracted from the sidewall of substrate 202C. Transparent conductive oxide layer 226C is on the sidewall of emitter region 216C1. According to one embodiment, as shown in the figure, transparent conductive oxide layer 226C is in a corresponding recessed portion between the corresponding sidewall of emitter region 216C1 and the corresponding sidewall of substrate 202C. In one such embodiment, as shown in the figure, the corresponding edge of transparent conductive oxide layer 226C is vertically aligned with the corresponding sidewall of substrate 202C. Conductive contact 220C is electrically connected to transparent conductive oxide layer 210C on emitter region 216C1.

[0073] Reference again Figure 2C In the embodiment of the present invention, in the embodiment of the present invention, the emitter layer 216C2 on the intrinsic layer 215C of the substrate 202C is at the second light receiving surface of the substrate 202C. The emitter region 216C2 has a conductivity type opposite to that of the emitter region 216C1. The emitter region 216C2 has a sidewall that is laterally retracted from the sidewall of the substrate 202C. The transparent conductive oxide layer 226C is on the sidewall of the emitter region 216C2. According to one embodiment, as shown in the figure, the transparent conductive oxide layer 226C is in a corresponding recessed portion between the corresponding sidewall of the emitter region 216C2 and the corresponding sidewall of the substrate 202C. In one such embodiment, as shown in the figure, the corresponding edge of the transparent conductive oxide layer 226C is vertically aligned with the corresponding sidewall of the substrate 202C. The conductive contact 220C is electrically connected to the transparent conductive oxide layer 210C on the emitter region 216C2.

[0074] refer to Figure 2CIn the embodiment of the present invention, the solar cell 250C includes a substrate 252C having a first (e.g., top) and a second (e.g., bottom) light receiving surface and a sidewall. The emitter layer 216C1 on the intrinsic layer 265C of the substrate 252C is at the first light receiving surface of the substrate 252C. The emitter region 266C1 has a sidewall that is laterally retracted from the sidewall of the substrate 252C. The transparent conductive oxide layer 276C is on the sidewall of the emitter region 266C1. According to one embodiment, as shown in the figure, the transparent conductive oxide layer 276C is in a corresponding groove between the corresponding sidewall of the emitter region 266C2 and the corresponding sidewall of the substrate 252C. In one such embodiment, as shown in the figure, the isolated emitter region portion is maintained as a transparent conductive oxide layer 276C that is laterally adjacent to the periphery of the solar cell 250C. The conductive contact 270C is electrically connected to the transparent conductive oxide layer 260C on the emitter region 266C1.

[0075] Reference again Figure 2C In the embodiment of the present invention, in the embodiment of the present invention, the emitter layer 266C2 on the intrinsic layer 265C of the substrate 252C is at the second light receiving surface of the substrate 252C. The conductivity type of the emitter region 266C2 is opposite to the conductivity type of the emitter region 266C1. The emitter region 266C2 has a sidewall that is laterally retracted from the sidewall of the substrate 252C. The transparent conductive oxide layer 276C is on the sidewall of the emitter region 266C2. According to one embodiment, as shown in the figure, the transparent conductive oxide layer 276C is in a corresponding groove between the corresponding sidewall of the emitter region 266C2 and the corresponding sidewall of the substrate 252C. In one such embodiment, as shown in the figure, the isolated emitter region portion remains as a transparent conductive oxide layer 276C that is laterally adjacent to the periphery of the solar cell 250C. The conductive contact 270C is electrically connected to the transparent conductive oxide layer 260C on the emitter region 266C2.

[0076] As an exemplary treatment process scheme, Figure 3 A plan view of forming a solar cell having an emitter region including laterally retracted protected edges is shown according to one embodiment of the present disclosure.

[0077] refer to Figure 3 Referring to part (A) of the present invention, a method for manufacturing a solar cell includes forming an emitter region in a substrate 300, the emitter region being at a light receiving surface of the substrate 300. Referring to part (B) or (C), a groove is formed in the emitter region. A passivation layer 218 or 268 is formed on the light receiving surface of the substrate and in the groove. The substrate is cut to form a solar cell having a sidewall and an emitter region having a sidewall that is laterally retracted from the sidewall of the solar cell.

[0078] Specifically refer to Figure 3In part (B), in one embodiment, cutting the substrate includes cutting through the passivation layer in the grooves to form cells 302, each of which has a passivation layer 224 / 226 in a corresponding recessed portion, as described above in conjunction with part (A) of Figure 2. Specifically referring to Figure 3 In another embodiment, cutting the substrate includes cutting through a portion of the emitter region of the laterally adjacent trenches to form cells 304, each of which has a passivation layer 274 / 276 in a corresponding trench, as described above in conjunction with Figure 2A as described in part (B).

[0079] In one embodiment, forming the grooves in the emitter region of the substrate 300 includes using laser ablation. In another embodiment, forming the grooves in the emitter region of the substrate 300 includes using an etching paste. In general, according to one or more embodiments of the present disclosure, a laser or inkjet or screen printing etching paste can be used to form isolation grooves, which can also be used to fully cut or even partially cut (e.g., half-cut) the battery to improve performance under low light conditions. In one embodiment, both cut edges are passivated even though the edge under overlap may not be very important because the diffusion length of the battery is much smaller than the overlap length. In other embodiments, only a single edge is passivated according to the above process.

[0080] Fig.13 1300 is a flowchart representing various operations in a method for manufacturing a solar cell according to an embodiment of the present disclosure. At operation 1302, the method includes forming an emitter region in a substrate, the emitter region being at a light receiving surface of the substrate. At operation 1304, the method includes forming a groove in the emitter region. At operation 1306, the method includes forming a passivation layer on the light receiving surface of the substrate and in the groove to passivate the emitter edge. At operation 1308, the method includes cutting the substrate to form a solar cell having sidewalls and an emitter region, the emitter region having sidewalls that are laterally retracted from the sidewalls of the solar cell. In one embodiment, a full groove method is used. In another embodiment, a partial groove method is used.

[0081] According to one or more embodiments of the present disclosure, an efficient stacking arrangement of silicon solar cells in a solar cell module is described herein. As an example, Figure 4 A cross-sectional view of a string of solar cells 402 connected in series in a shingled arrangement is shown with ends of adjacent solar cells overlapping and electrically connected to form super cell 400. Each solar cell 402 includes a semiconductor diode structure and its electrical contacts through which current generated when solar cell 402 is illuminated by light can be provided to an external load.

[0082] In the examples described in this specification, each solar cell 402 is a crystalline silicon solar cell having a front surface (sun side) metallization pattern and a back surface (shadow side) metallization pattern, the front surface metallization pattern being disposed on a semiconductor layer of n-type conductivity, and the back surface metallization pattern being disposed on a semiconductor layer of p-type conductivity, the metallization patterns providing electrical contacts for opposite sides of the np junction. However, any other suitable solar cell using any other suitable material system, diode structure, physical size, or electrical contact arrangement may replace or assist the solar cell 402 in the solar module described in this specification. For example, the front surface (sun side) metallization pattern may be disposed on a semiconductor layer of p-type conductivity, and the back surface (shadow side) metallization pattern may be disposed on a semiconductor layer of n-type conductivity.

[0083] Reference again Figure 4 , adjacent solar cells 402 in super cell 400 are conductively bonded to each other in a region where the adjacent solar cells overlap by a conductive bonding material that electrically connects the front surface metallization pattern of one solar cell to the back surface metallization pattern of an adjacent solar cell. Suitable conductive bonding materials may include, for example, conductive adhesives, conductive adhesive films and tapes, and conventional solders. Preferably, the conductive bonding material provides mechanical compliance in the bond between adjacent solar cells that accommodates stresses caused by a mismatch between the coefficient of thermal expansion (CTE) of the conductive bonding material and the coefficient of thermal expansion of the solar cells (e.g., the CTE of silicon). To provide such mechanical compliance, in some variations the conductive bonding material is selected to have a glass transition temperature of less than or equal to about 0°C. To further reduce and accommodate stresses parallel to the overlapping edges of the solar cells caused by CTE mismatch, the conductive bonding material may optionally be applied only at discrete locations along the overlapping region of the solar cells, rather than in a continuous line extending substantially along the length of the edge of the solar cell.

[0084] The thickness of the conductive bonds formed of the conductive bonding material between adjacent overlapping solar cells may be, for example, less than about 0.1 mm, measured perpendicular to the front and back surfaces of the solar cells. Such thin bonds reduce resistive losses at the interconnection locations between the cells and also facilitate the flow of heat along the super cell from any hot spots that may form in the super cell during operation.

[0085] Figure 5The front surface of an exemplary rectangular solar cell 402 that may be used in super cell 400 is shown. Other suitable shapes may be used for solar cell 402. That is, solar cell 402 need not be rectangular. In the illustrated example, the front surface metallization pattern of solar cell 402 includes bus bar 500 positioned adjacent to an edge of a long side of solar cell 402 and extending parallel to the long side for substantially the length of the long side, and fingers 502 attached perpendicularly to the bus bar and extending parallel to each other and parallel to the short sides of solar cell 402 for substantially the length of the short sides.

[0086] exist Figure 5 In the example of , the solar cell 402 has a length of about 156 mm, a width of about 26 mm, and thus has an aspect ratio (short side length / long side length) of about 1:6. Six such solar cells can be made on a silicon wafer of standard size 156 mm×156 mm, and then separated (cut) to provide solar cells as shown. In other variations, eight solar cells 402 can be made from a standard silicon wafer, and these solar cells 402 have a size of about 19.5 mm×156 mm, and thus have an aspect ratio of about 1:8. More generally, the solar cell 402 can have an aspect ratio of, for example, about 1:2 to about 1:20, and can be made from a standard size wafer or any other suitable size wafer. It should be understood that silicon wafers larger than 156 mm×156 mm can be used, such as silicon wafers having an area of ​​156.75 mm×156.75 mm, 158.75 mm×158.75 mm, 161.75 mm×161.75 mm, or even larger. In other embodiments, silicon wafers smaller than 156 mm x 156 mm may be used.

[0087] Fig. 6A An exemplary method is shown that may be used to cut, divide or otherwise separate a pseudo-square silicon solar cell wafer 600 of standard size and shape to form rectangular solar cells, as described above. In this example, several full width rectangular solar cells are cut from the center portion of the wafer, and several shorter rectangular solar cells 402S are cut from the ends of the wafer, and the chamfered or rounded corners of the wafer are discarded. The solar cells may be used to form shingled super cells of one width, and solar cells 402S may be used to form shingled super cells of a narrower width.

[0088] Figure 6B and 6C 1 and 10 show a front view and a back view of a pseudo square wafer 600, which can be formed along Figure 6C The dashed lines shown are cut to provide multiple Figure 5A solar cell 402 with a front surface metallization pattern and two chamfered solar cells 402 with a front surface metallization pattern are shown.

[0089] exist Figure 6B In the exemplary front surface metallization pattern shown, both ends of the thin conductor interconnecting the discrete contact pads 500 extend around the chamfer of the solar cell and taper as the distance from the long side of the solar cell increases, along which the discrete contact pads are arranged. Such taper is optional, but can be advantageous in reducing metal usage and shading of the active area of ​​the solar cell without significantly increasing resistive losses.

[0090] Fig.6D and 6E 606, which can be arranged along the Fig. 6E The dashed lines shown are cut to provide multiple Figure 5 A solar cell 402 is shown with a front surface metallization pattern.

[0091] Chamfered rectangular solar cells may be used to form super cells that include only chamfered solar cells. Additionally or alternatively, one or more such chamfered rectangular solar cells may be combined with one or more non-chamfered rectangular solar cells (e.g., Figure 5 ) to form a super cell. For example, the end solar cells of a super cell may be chamfered solar cells and the middle solar cells may be non-chamfered solar cells. If chamfered solar cells are used in combination with non-chamfered solar cells in a super cell or more generally in a solar module, it may be desirable to use solar cells of appropriate size so that the chamfered and non-chamfered solar cells have the same front surface area exposed to light during operation of the solar cell. By matching the solar cell area in this way, the current produced in the chamfered and non-chamfered solar cells may be matched, thereby improving the performance of series-connected strings of cells including chamfered and non-chamfered solar cells. The areas of chamfered and non-chamfered solar cells cut from the same pseudo-square wafer may be matched, for example, by adjusting the position of the lines cut into the wafer so that the chamfered solar cells are slightly wider than the non-chamfered solar cells in a direction perpendicular to their long axis to compensate for the missing corners on the chamfered solar cells.

[0092] A solar module may include only super cells formed from rectangular solar cells without chamfered corners, or only super cells formed from rectangular solar cells with chamfered corners, or only super cells formed from solar cells with chamfered corners and without chamfered corners, or any combination of these three variations of super cells.

[0093] In some examples, portions of a standard sized square or pseudo-square solar cell wafer (e.g., wafer 600 or wafer 606) near the edge of the wafer may convert light into electrical energy less efficiently than portions of the wafer further from the edge. To improve the efficiency of the resulting rectangular solar cell, in some variations, one or more edges of the wafer are trimmed to remove less efficient portions prior to wafer slicing. The portions trimmed from the edge of the wafer may have a width of, for example, about 1 mm to about 5 mm. Additionally, as Figure 6B and 6C As shown, the front surfaces of two end solar cells 402 to be cut from the wafer may be oriented with their front surface bus bars (or discrete contact pads) 500 extending along their outer edges and thus along both edges of the wafer. Because bus bars (or discrete contact pads) 500 are typically overlapped by adjacent solar cells in the super cells disclosed herein, lower light conversion efficiency along both edges of the wafer does not typically affect the performance of the solar cells. Thus, in some variations, the edges of the square or pseudo-square wafer parallel to the short sides of the rectangular solar cells are trimmed, as described above, but the edges of the wafer parallel to the long sides of the rectangular solar cells are not trimmed. In other variations, a square wafer (e.g., Fig.6D One, two, three or four edges of the wafer 606 in the above-mentioned embodiment are trimmed, as described above. In other variations, one, two, three or four long edges of the pseudo-square wafer are trimmed, as described above.

[0094] As shown, solar cells having a long and narrow aspect ratio and having an area smaller than a standard 156 mm x 156 mm solar cell may be advantageously used to reduce resistive power losses in the solar cell modules disclosed herein. Specifically, the reduced area of ​​solar cell 402 reduces the current produced in the solar cell compared to standard sized silicon solar cells, thereby directly reducing resistive power losses in the solar cell and in strings of such solar cells connected in series. Additionally, arranging such rectangular solar cells in super cell 400 so that current flows through the super cells parallel to the short sides of the solar cell may reduce the distance that current must flow through the semiconductor material to reach fingers 502 in the front surface metallization pattern and reduce the required finger length, which may also reduce resistive power losses.

[0095] As described above, bonding overlapping solar cells 402 to each other in their overlapping regions to electrically connect the solar cells in series shortens the length of the electrical connection between adjacent solar cells, compared to conventional protruding serially connected solar cell strings. This also reduces resistive power losses.

[0096] Reference again Figure 5In the example shown, the front surface metallization pattern on the solar cell 402 includes an optional bypass conductor 504 extending parallel to and spaced apart from the bus bar 500. (Such a bypass conductor may also be optionally used for Figure 6B and 6D ) Bypass conductor 504 is interconnected with finger 502 to electrically bypass cracks that may be formed between busbar 500 and bypass conductor 504. Such cracks that may cut off finger 502 at a position close to busbar 500 may otherwise isolate the region of solar cell 402 from busbar 500. Bypass conductor provides an alternative electrical path between such cut-off fingers and busbar. The example shown shows bypass conductor 504 positioned parallel to busbar 500, extending around the entire length of the busbar and interconnecting each finger 502. This arrangement may be preferred, but is not required. If present, bypass conductor does not necessarily extend parallel to the busbar, nor does it necessarily extend along the entire length of the busbar. In addition, the bypass conductor interconnects at least two fingers, but does not necessarily interconnect all fingers. For example, two or more short bypass conductors may be used instead of a longer bypass conductor. Any suitable arrangement of bypass conductors may be used.

[0097] Figure 5 The exemplary front surface metallization pattern of FIG. 5 also includes an optional end conductor 506 that interconnects the finger 502 at its distal end, which is opposite the bus bar 500. (Such an end conductor may also be optionally used for Figure 6B and 6D ) The width of conductor 506 can be, for example, about the same as the width of finger 502. Conductor 506 is interconnected with finger 502 to electrically bypass cracks that may form between bypass conductor 504 and conductor 506, thereby providing a current path for bus bar 500 in areas of solar cell 402 that may otherwise be electrically isolated by such cracks.

[0098] Although a portion of the illustrated examples show a front bus bar 500 extending substantially along the length of the long sides of the solar cell 402 with a uniform width, the front bus bar 500 is not required. For example, as mentioned above, the front bus bar 500 may be replaced by two or more front surface discrete contact pads 500, which may be arranged in a row with each other along the side of the solar cell 402, for example Figure 6BAs shown. Such discrete contact pads may optionally be interconnected by thinner conductors extending between them, such as shown in the above-mentioned figures. In such variants, the width of the contact pad measured perpendicular to the long side of the solar cell may be, for example, about 2 times to about 20 times the width of the thin conductor that interconnects the contact pads. Each finger in the front surface metallization pattern may have a separate (e.g., small) contact pad, or each contact pad may be connected to two or more fingers. For example, the front surface contact pad 500 may be a square or a rectangular shape having an elongated edge parallel to the solar cell. The front surface contact pad 500 may have a width perpendicular to the long side of the solar cell of, for example, about 1 mm to about 1.5 mm, and have a length parallel to the long side of the solar cell of, for example, about 1 mm to about 10 mm. For example, the spacing between the contact pads 500 measured parallel to the long side of the solar cell may be about 3 mm to about 30 mm.

[0099] Alternatively, the solar cell 402 may lack both the front bus bar 500 and the discrete front contact pad 500, and include only the fingers 502 in the front surface metallization pattern. In such variations, the current collecting function originally performed by the front bus bar 500 or the contact pad 500 may instead or partially be performed by the conductive material used to bond the two solar cells 402 to each other in the overlapping configuration described above.

[0100] Solar cells lacking both the front bus bar 500 and the contact pad 500 may include the bypass conductor 504, or may not include the bypass conductor 504. If the bus bar 500 and the contact pad 500 are not present, the bypass conductor 504 may be arranged to bypass a crack formed between the bypass conductor and a portion of the front surface metallization pattern that is conductively bonded to the overlapping solar cell.

[0101] The front surface metallization pattern including busbars or discrete contact pads 500, fingers 502, bypass conductors 504 (if present) and end conductors 506 (if present) can be formed, for example, by depositing a silver paste commonly used for such purposes by, for example, conventional screen printing methods. Alternatively, the front surface metallization pattern can be formed by electroplating copper. Any other suitable materials and processes can also be used. In a variant in which the front surface metallization pattern is formed of silver, the use of discrete front surface contact pads 500 rather than a continuous busbar 500 along the edge of the cell reduces the silver content on the solar cell, which can advantageously reduce costs. In a variant in which the front surface metallization pattern is formed of copper or by another conductor that is cheaper than silver, a continuous busbar 500 can be used without cost disadvantages.

[0102] Figure 6C and 6EExample back surface metallization patterns of solar cells are shown. In these examples, the back surface metallization pattern includes discrete back surface contact pads 602 arranged along one of the long sides of the back surface of the solar cell, and metal contacts 604 covering substantially all of the remaining back surface of the solar cell. In a shingled super cell, contact pads 602 are bonded, for example, to bus bars or discrete contact pads arranged along the edges of the upper surfaces of adjacent overlapping solar cells to electrically connect the two solar cells in series. For example, each discrete back surface contact pad 602 may be aligned with and bonded to a corresponding discrete front surface contact pad 500 on the front surface of the overlapping solar cell by applying conductive bonding material only to the discrete contact pad. Discrete contact pads 602 may be square or have a rectangular shape that is elongated parallel to the edges of the solar cell (e.g., Figure 6C and 6E ). The contact pads 602 may have a width perpendicular to the long side of the solar cell of, for example, about 1 mm to about 5 mm, and a length parallel to the long side of the solar cell of, for example, about 1 mm to about 10 mm. For example, the spacing between the contact pads 602 measured parallel to the long side of the solar cell may be about 3 mm to about 30 mm.

[0103] The contacts 604 may be formed, for example, of aluminum and / or electroplated copper. The formed aluminum back contacts 604 generally provide a back surface electric field that reduces back surface recombination in the solar cell, thereby improving solar cell efficiency. If the contacts 604 are formed of copper rather than aluminum, the contacts 604 may be used in conjunction with another passivation scheme (e.g., aluminum oxide) to similarly reduce back surface recombination. The discrete contact pads 602 may be formed, for example, of silver paste. The use of discrete silver contact pads 602 rather than a continuous silver contact pad arranged along the edge of the cell reduces the silver content in the back surface metallization pattern, which may advantageously reduce costs.

[0104] Additionally, if the solar cell relies on the back surface electric field provided by forming aluminum contacts to reduce back surface recombination, using discrete silver contacts rather than continuous silver contacts can improve solar cell efficiency. This is because the silver back surface contacts do not provide a back surface electric field and therefore tend to promote carrier recombination and create dead (ineffective) volumes in the solar cell above the silver contacts. In conventional ribbon-shaped protruding solar cell strings, those dead volumes are typically blocked by the strips and / or bus bars on the front surface of the solar cell and therefore do not cause any additional efficiency loss. However, in the solar cells and super cells disclosed herein, the volume of the solar cell above the back surface silver contact pads 602 is generally unaffected by any front surface metallization, and any dead volume caused by the use of silver back surface metallization reduces the efficiency of the cell. Therefore, using discrete silver contact pads 602 rather than continuous silver contact pads along the back surface edge of the solar cell reduces the volume of any corresponding dead area and improves the efficiency of the solar cell.

[0105] Although the particular exemplary solar cells shown in the figures are described as having a particular combination of front and back surface metallization patterns, more generally, any suitable combination of front and back surface metallization patterns may be used. For example, one suitable combination may employ a silver front surface metallization pattern including discrete contact pads 500, fingers 502, and optional bypass conductors 504, and a back surface metallization pattern including aluminum contacts 604 and discrete silver contact pads 602. Another suitable combination may employ a copper front surface metallization pattern including continuous bus bars 500, fingers 502, and optional bypass conductors 504, and a back surface metallization pattern including continuous bus bars 602 and copper contacts 604. More generally, solar cells 402 may employ any suitable front and back surface metallization patterns.

[0106] Figure 7 FIG. 4 shows a portion of the front surface of an exemplary rectangular super cell 400 including: Figure 5 As shown Figure 4 4. ...

[0107] exist Figure 7In the example shown, the bypass conductor 504 is hidden in the overlapping portion of the adjacent cells. Alternatively, the solar cell including the bypass conductor 504 can be arranged in accordance with Figure 7 The bypass conductors are overlapped but not covered in a similar manner as shown.

[0108] Exposed front surface bus bar 500 at one end of super cell 400 and back surface metallization of the solar cell at the other end of super cell 400 provide the super cell with negative and positive electrodes (terminals) that can be used to electrically connect super cell 400 to other super cells and / or other electrical components as desired.

[0109] Adjacent solar cells in super cell 400 may overlap by any suitable amount, for example, from about 1 millimeter (mm) to about 5 mm.

[0110] like Figures 8A-8D As shown, for example, the shingled super cells described above can efficiently fill the area of ​​a solar module. For example, the solar module can be square or rectangular. Figures 8A-8D The short sides of the rectangular solar module shown may be, for example, about 1 meter in length, while the long sides may be, for example, about 1.5 meters to about 2.0 meters in length. Any other suitable shapes and sizes of solar modules may be used. Any suitable arrangement of super cells may be used in a solar module.

[0111] In square or rectangular solar modules, super cells are typically arranged in rows parallel to the short or long sides of the solar module. Each row may include one, two or more super cells arranged end to end. Super cells 400 forming part of such a solar module may include any suitable number of solar cells 402 and may be of any suitable length. In some variations, super cells 400 each have a length approximately equal to the length of the short side of the rectangular solar module of which they are composed. In other variations, super cells 400 each have a length approximately equal to half the length of the short side of the rectangular solar module of which they are composed. In other variations, super cells 400 each have a length approximately equal to the length of the long side of the rectangular solar module of which they are composed. In other variations, super cells 400 each have a length approximately equal to half the length of the long side of the rectangular solar module of which they are composed. The number of solar cells required to produce super cells of these lengths will, of course, depend on the size of the solar module, the size of the solar cells, and the amount of overlap of adjacent solar cells. Any other suitable length may also be used for super cells.

[0112] In variations where super cell 400 has a length approximately equal to the length of the short side of a rectangular solar module, the super cell may comprise, for example, 56 rectangular solar cells measuring about 19.5 millimeters (mm) by about 156 mm, with adjacent solar cells overlapping by about 3 mm. Eight such rectangular solar cells may be singulated from a conventional 156 mm square or pseudo-square wafer. Alternatively, such a super cell may comprise, for example, 38 rectangular solar cells measuring about 26 mm by about 156 mm, with adjacent solar cells overlapping by about 2 mm. Six such rectangular solar cells may be singulated from a conventional 156 mm square or pseudo-square wafer. In variations where super cell 400 has a length approximately equal to half the length of the short side of a rectangular solar module, the super cell may comprise, for example, 28 rectangular solar cells measuring about 19.5 millimeters (mm) by about 156 mm, with adjacent solar cells overlapping by about 3 mm. Alternatively, such a super cell may comprise, for example, 19 rectangular solar cells measuring about 26 mm by about 156 mm, with adjacent solar cells overlapping by about 2 mm.

[0113] In the variation where the length of super cell 400 is approximately equal to the length of the long side of a rectangular solar module, the super cell may comprise, for example, 72 rectangular solar cells measuring about 26 mm by about 156 mm, with adjacent solar cells overlapping by about 2 mm. In the variation where the length of super cell 400 is approximately equal to half the length of the long side of a rectangular solar module, the super cell may comprise, for example, 36 rectangular solar cells measuring about 26 mm by about 156 mm, with adjacent solar cells overlapping by about 2 mm.

[0114] Fig. 8A An example rectangular solar module 800 is shown comprising twenty rectangular super cells 400, each having a length approximately equal to half the length of the short side of the solar module. The super cells are arranged in pairs end-to-end to form ten rows of super cells with the long sides of the rows and super cells oriented parallel to the short sides of the solar module. In other variations, each row of super cells may comprise three or more super cells. Additionally, similarly constructed solar modules may include more or fewer rows of super cells than shown in this example.

[0115] It will be appreciated that in variations in which each row of super cells is arranged so that at least one of them has a front surface end contact at the end of the super cell adjacent to the other super cells in the row, a gap may facilitate electrical contact with the front surface end contact of super cell 400 along the centerline of the solar module. For example, two super cells in the row may be arranged so that one super cell has a front surface end contact along the centerline of the solar module and the other super cell has a back surface end contact along the centerline of the solar module. In such an arrangement, the two super cells in a row may be electrically connected in series with an interconnect arranged along the centerline of the solar module and bonded to the front surface end contact of one super cell and the back surface end contact of the other super cell. (See, for example, the interconnect described below.) Fig. 10C ) In variations where each row of super cells comprises three or more super cells, additional spacing may be present between super cells and may similarly facilitate electrical contact with front surface end contacts away from the sides of the solar module.

[0116] Figure 8B An example rectangular solar module 803 is shown comprising ten rectangular super cells 400, each having a length approximately equal to the length of the short side of the solar module. The super cells are arranged in ten parallel rows with their long sides oriented parallel to the short sides of the module. Similar configured solar modules may also include super cells of this length, but with more or fewer rows than shown in this example.

[0117] Figure 8B Also shown is that when there are no gaps between adjacent super cells in a row of super cells in solar module 800, Fig. 8A 800. It will be appreciated that the gap may be eliminated, for example, by arranging the super cells so that both super cells in each row have back surface end contacts along the centerline of the module. In this case, since the front surfaces of the super cells do not need to be touched along the center of the module, the super cells may be arranged nearly adjacent to each other with little or no additional gap between them. Alternatively, two super cells 400 in a row may be arranged so that one super cell has a front surface end contact along a side of the module and a back surface end contact along the centerline of the module, and the other super cell has a front surface end contact along the centerline of the module and a back surface end contact along an opposite side of the module, with adjacent ends of the super cells overlapping. A flexible interconnect may be sandwiched between the overlapping ends of the super cells without obscuring any portion of the front surface of the solar module to provide electrical connection to the front surface end contact of one of the super cells and the back surface end contact of the other super cell. A combination of these two approaches may be used for rows of three or more super cells.

[0118] Fig. 8A and 8B The super cells and rows of super cells shown in FIG. 1 may be interconnected by any suitable combination of series and parallel electrical connections. The interconnections between super cells may be made, for example, using circuits similar to those described below with respect to FIG. Figure 8C and 8D The flexible interconnection is achieved.

[0119] Figure 8C An exemplary rectangular solar module 804 is shown that includes six rectangular super cells 400, each having a length approximately equal to the length of the long side of the solar module. The super cells are arranged in six parallel columns with their long sides oriented parallel to the long sides of the module. Similar configured solar modules may also include super cells of this length, but in more or fewer columns than shown in this example. Each super cell in this example (and in the examples that follow) includes 72 rectangular solar cells, each having a width approximately equal to 1 / 6 of the width of a 156 mm square or pseudo-square wafer. Any other suitable number of rectangular solar cells of any other suitable size may also be used. In this example, the front surface terminal contacts of the super cells are electrically connected to each other by flexible interconnects 806 that are positioned adjacent to and extend parallel to the edge of one short side of the module. The back surface terminal contacts of the super cells are similarly electrically connected to each other by flexible interconnects that are positioned adjacent to and extend parallel to the edge of the other short side at the rear of the solar module. The back surface interconnects are located at the Figure 8C This arrangement connects six modules of super cells in parallel.

[0120] Fig.8DAn exemplary rectangular solar module 812 is shown that includes twelve rectangular super cells 400, each having a length approximately equal to half the length of the long side of the solar module. The super cells are arranged in pairs in an end-to-end arrangement to form six rows of super cells, with the rows of super cells and the long sides of the super cells oriented parallel to the long sides of the solar module. In other variations, each row of super cells may include three or more super cells. In addition, similarly configured solar modules may include more or fewer rows of super cells than shown in this example. Each super cell in this example (and in the examples that follow) includes 36 rectangular solar cells, each having a width approximately equal to 1 / 6 of the width of a 156 mm square or pseudo-square wafer. Any other suitable number of rectangular solar cells having any other suitable dimensions may also be used. It will be appreciated that gaps may be used to facilitate electrical contact with the front surface end contacts of super cells 400 along the centerline of the solar module. In this example, flexible interconnect 806 is positioned adjacent to and extends parallel to the edge of one of the short sides of the module to electrically interconnect the front surface terminal contacts of six of the super cells. Similarly, a flexible interconnect is positioned adjacent to and extends parallel to the edge of the other short side of the module behind the module to electrically connect the back surface terminal contacts of six more super cells. Flexible interconnects (not shown in this figure) may be positioned in series along the gap between each pair of super cells and may optionally extend laterally to interconnect adjacent rows in parallel. This arrangement electrically connects the six rows of super cells in parallel. Optionally, in the first group of super cells, the first super cell in each row is electrically connected in parallel with the first super cell in each other row, in the second group of super cells, the second super cell is electrically connected in parallel with the second super cell in each other row, and the two groups of super cells are electrically connected in series. The subsequent arrangement connects each of the two groups of super cells in parallel with a bypass diode.

[0121] Fig.8D Details in A logo Fig. 10A A cross-sectional view of the location of the interconnection of the super cell back surface terminal contacts along the edge of one short side of the module is shown in FIG. Detail B is similarly identified Fig. 10B A cross-sectional view showing the location of the interconnection of the super cell front surface terminal contacts along the edge of the other short side of the module. Detail C logo Fig. 10C 808.

[0122] In other examples, a solar cell module is manufactured using half-cut solar cells. According to one embodiment of the present disclosure, Fig. 8E shows a plan view of a solar cell platform including half-cut cells, and Figure 8F Show Fig. 8EAn enlarged view of a portion of a solar cell module.

[0123] refer to Fig. 8E and 8F , module 820 includes half-cut solar cells 822. In one embodiment, as Figure 8F As shown, the cells are arranged in alternating columns of upward half-cut cells 822A and downward half-cut cells 822B. Fig. 8E As shown, the arrangement of modules 820 may include a centerline 824. In other embodiments, such a centerline is not included.

[0124] It should be understood that other stacked module arrangements can be made. As an example, Figure 8G A plan view of a solar cell module according to one embodiment of the present disclosure is shown, the solar cell module including a vertical shingled strand with a rectangular strip arrangement. Figure 8G , module 830 includes vertical strips 832 of rectangular solar cells 834 .

[0125] As another example, Figure 8H A plan view of a solar cell module including a vertical strand with a stacked chamfered cell arrangement according to one embodiment of the present disclosure is shown. Figure 8H , module 840 includes vertical strips of chamfered solar cells 842 .

[0126] As another example, Fig.8I A plan view of a solar cell module according to one embodiment of the present disclosure is shown, the solar cell module including a vertical stranding with stacked cells and a centerline arrangement. Fig.8I , module 850 includes vertical strips 852 of chamfered solar cells 854. In other embodiments, rectangular cells are used. As shown, the arrangement of module 850 may include a centerline 856. In other embodiments, such a centerline is not included.

[0127] Fig. 9 Compare Figure 8C and 8D An example arrangement of three rows of super cells is shown in more detail, interconnected with flexible electrical interconnects to connect the super cells in series with each other within each row and to connect the rows parallel to each other. For example, these may be Fig.8D Three rows of solar modules. Fig. 9In the example of FIG. 4 , each super cell 400 has a flexible interconnect 806 conductively bonded to its front surface terminal contact and another flexible interconnect conductively bonded to its back surface terminal contact. The two super cells in each row are electrically connected in series by a shared flexible interconnect conductively bonded to the front surface terminal contact of one super cell and to the back surface terminal contact of the other super cell. Each flexible interconnect is positioned near and parallel to the end of the super cell to which it is bonded and may extend laterally beyond the super cell to conductively bond to a flexible interconnect on a super cell in an adjacent row, electrically connecting the adjacent row in parallel. Fig. 9 Dashed lines in the ?g show portions of the flexible interconnect that are hidden by overlapping portions of the super cell, or portions of the super cell that are hidden by overlapping portions of the flexible interconnect.

[0128] Flexible interconnect 806 may be electrically bonded to the super cell by a mechanically compliant conductive bonding material such as described above for bonding overlapping solar cells. Optionally, the conductive bonding material may be located only at discrete locations along the edge of the super cell rather than in a continuous line running substantially the length of the edge of the super cell, to reduce or accommodate stresses parallel to the super cell edge caused by a mismatch between the coefficient of thermal expansion of the conductive bonding material or interconnect and that of the super cell.

[0129] For example, flexible interconnect 806 may be formed of or include a thin copper sheet. Flexible interconnect 806 may optionally be patterned or otherwise configured to increase its mechanical compliance (flexibility) perpendicular and parallel to the edges of the super cells to reduce or accommodate stresses perpendicular and parallel to the super cell edges caused by a mismatch between the CTE of the interconnect and the CTE of the super cell. Such patterning may include, for example, slits, slots, or holes. The conductive portion of interconnect 806 may have a thickness of, for example, less than about 100 microns, less than about 50 microns, less than about 30 microns, or less than about 25 microns to increase the flexibility of the interconnect. The mechanical compliance of the flexible interconnect and its incorporation into the super cells should be sufficient to withstand stresses caused by CTE mismatch during lamination as described in detail below with respect to methods of making solar cell modules, and to withstand stresses due to CTE mismatch during temperature cycling testing between about -40°C and about 85°C. Preferably, flexible interconnect 806 exhibits a resistance to current flow parallel to the super cell ends to which it is bonded of about 0.015 ohms or less, about 0.012 ohms or less, or about 0.01 ohms or less.

[0130] like Figures 10A-10C, for example, a solar module described herein generally comprises a laminate structure having super cells and one or more encapsulant materials 808 sandwiched between a transparent front sheet 1000 and a back sheet 1002. The transparent front sheet may be, for example, glass. Optionally, the back sheet may also be transparent, which may allow the solar module to operate bifacially. The back sheet may be, for example, a polymer sheet. Alternatively, the solar module may be a glass-glass module having both a front glass sheet and a back glass sheet.

[0131] Fig. 10A Cross-sectional view ( Fig.8D Detail A) shows an example of a flexible interconnect 806 conductively bonded to a super cell back surface terminal contact near the edge of the solar template and extending inwardly below the super cell, hidden from view from the front side of the solar module. As shown, an additional encapsulant strip 1004 may be provided between interconnect 806 and the back surface of the super cell. Glued or welded joints 1006 may also be included as shown.

[0132] Fig. 10B Cross-sectional view ( Figure 8B Detail B) shows an example of flexible interconnect 806 conductively bonded to a front surface terminal contact of a super cell. Glued or welded joint 1008 may also be included as shown.

[0133] Fig. 10C Cross-sectional view ( Figure 8B Detail C) shows an example of a shared flexible interconnect 806 conductively bonded to the front surface terminal contact of one super cell and to the back surface terminal contact of another super cell to electrically connect the two super cells in series. The interconnect may include an optional black film or coating 1014. Glued or welded joints 1010 and / or 1012 may also be included as shown.

[0134] According to an embodiment, the modules themselves may be stacked together such that the top strip is covered by the adjacent modules. Fig.11 A simplified cross-sectional view of such an arrangement 1100 is shown, wherein the end 1101 of an adjacent module 1102 is used to overlap with the top band 1104 of an instant module 1106. Each module itself includes a plurality of shingled solar cells 1107. The bottom band 1108 of the instant module 1106 is buried. It is located on the raised side of the instant shingled module so as to overlap the next adjacent shingled module. The shingled module configuration can also provide additional area on the module for other elements without adversely affecting the final exposed area of ​​the module array. Examples of module elements that can be positioned in the overlapping area can include, but are not limited to, junction boxes (j-boxes) 1110 and / or busbars.

[0135] Fig.12 Another embodiment of a stacked module configuration 1200 is shown. Therein, the j-boxes 1202, 1204 of each adjacent stacked module 1206 and 1208 are in a mating arrangement 1210 to enable electrical connection therebetween. This simplifies the configuration of the stacked module array by eliminating wiring. In certain embodiments, the j-box may be enhanced and / or combined with additional structural supports. Such a configuration may create an integrated tilted module roof mounting solution, where the size of the junction box determines the tilt angle. Such an embodiment may be particularly applicable when installing a stacked module array on a flat roof. If the module includes a glass substrate and a glass cover (glass-glass module), the module may be used by shortening the overall length of the module (and therefore shortening the exposed length L caused by the stacking) without the need for additional frame members. Such shortening will enable the modules of the tilted array to withstand the expected physical loads (e.g., 5400Pa snow load limit) without breaking under strain.

[0136] It will be appreciated that the use of a super cell structure comprising multiple individual solar cells assembled together in a shingled fashion can be readily adapted to vary the length of the module to conform to a particular length dictated by physical loading and other requirements.

[0137] It should also be understood that one or more of the processes described above may be implemented to manufacture solar cells. All of the above processes may be implemented, or portions of one or more of the above processes may be implemented to manufacture solar cells. Although front-contact solar cells are described in detail above, it should be understood that interdigitated back-contact (IBC) solar cell manufacturing processes may also benefit from implementing the embodiments disclosed herein.

[0138] Although certain materials are specifically described with reference to the above embodiments, in such embodiments, other materials may be easily substituted for some of the materials, and these embodiments remain within the spirit and scope of the embodiments of the present disclosure. For example, in a certain embodiment, a substrate of a different material, such as a substrate of a III-V material, may be used instead of a silicon substrate. In addition, it should be understood that where the order of P+ type and then N+ type doping is specifically described for the emitter region on the back surface of the solar cell, other contemplated embodiments include the opposite order of conductivity types, such as N+ type and then P+ type doping. In other embodiments, a P-type doped substrate is used instead of an N-type doped substrate. In other embodiments, the above method may be applicable to the manufacture of things other than solar cells. For example, the manufacture of light emitting diodes (LEDs) may benefit from the methods described herein.

[0139] Thus, there have been disclosed methods of making solar cells having junctions retracted from cut edges, and the resulting solar cells.

[0140] Although specific embodiments have been described above, even if only a single embodiment is described with respect to a particular feature, these embodiments are not intended to limit the scope of the present disclosure. Unless otherwise specified, the examples of features provided in the present disclosure are intended to be illustrative rather than limiting. The above description is intended to cover those alternatives, modifications, and equivalents that will be apparent to those skilled in the art that have the beneficial effects of the present disclosure.

[0141] The scope of the present disclosure includes any feature or combination of features disclosed herein (expressly or implicitly), or any generalization thereof, whether or not it mitigates any or all of the problems addressed herein. Accordingly, new claims may be made for any such combination of features during the examination process of the present application (or an application claiming priority thereto). In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims, and features from corresponding independent claims may be combined in any appropriate manner, and not just in the specific forms enumerated in the appended claims.

[0142] The following embodiments relate to further embodiments. The various features of the different embodiments can be combined in various ways with some features included and other features excluded to suit various different applications.

[0143] Example embodiment 1: A solar cell includes a substrate having a light receiving surface, a back surface and sidewalls. An emitter region is located in the substrate at the light receiving surface of the substrate, the emitter region having sidewalls that are laterally retracted from the sidewalls of the substrate. A passivation layer is on the sidewalls of the emitter region.

[0144] Exemplary embodiment 2: The solar cell according to Exemplary embodiment 1, wherein the passivation layer is in a corresponding recessed portion between a corresponding sidewall of the emitter region and a corresponding sidewall of the substrate.

[0145] Exemplary embodiment 3: The solar cell according to Exemplary embodiment 2, wherein corresponding edges of the passivation layer are vertically aligned with corresponding side walls of the substrate.

[0146] Exemplary Embodiment 4: The solar cell according to Exemplary Embodiment 1, wherein the passivation layer is in the corresponding groove between the corresponding sidewall of the emitter region and the corresponding sidewall of the substrate.

[0147] Exemplary embodiment 5: The solar cell according to exemplary embodiment 1, 2, 3 or 4, further comprising a passivation layer on the light receiving surface of the substrate, wherein the passivation layer on the sidewall of the emitter region is continuous with the passivation layer on the light receiving surface of the substrate.

[0148] Exemplary Embodiment 6: The solar cell according to Exemplary Embodiment 5, wherein the passivation layer on the light receiving surface of the substrate and the passivation layer on the sidewall of the emitter region include silicon oxide (SiOx) and silicon nitride (SiNx).

[0149] Exemplary embodiment 7: According to the solar cell described in exemplary embodiments 1, 2, 3, 4, 5 or 6, wherein the emitter region contains a certain concentration of conductive type dopants, the solar cell may further include a conductive type dopant region within the emitter region, the concentration of conductive type dopant in the conductive type dopant region being higher than the concentration of conductive type dopant in the emitter region.

[0150] Exemplary Embodiment 8: The solar cell according to Exemplary Embodiment 7, wherein the conductivity type is n-type, and the dopant is selected from the group consisting of: a phosphorus dopant and an arsenic dopant.

[0151] Exemplary Embodiment 9: The solar cell according to Exemplary Embodiment 7 or 8, further comprising conductive contacts electrically connected to the conductive type dopant region in the emitter region.

[0152] Example Embodiment 10: The solar cell of Example Embodiment 9, wherein the conductive contacts are screen printed and fired through the passivation layer on the light receiving surface of the substrate.

[0153] Exemplary Embodiment 11: The solar cell according to Exemplary Embodiment 9 or 10, wherein the conductive contact comprises silver.

[0154] Exemplary embodiment 12: The solar cell according to exemplary embodiment 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein the substrate is a p-type single crystal silicon substrate.

[0155] Example 13: The solar cell of Example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, wherein the emitter region comprises an n-type dopant, the solar cell further comprising a p-type dopant region on the back surface of the substrate.

[0156] Exemplary Embodiment 14: The solar cell according to Exemplary Embodiment 13, further comprising a conductive contact electrically connected to the p-type dopant region on the back surface of the substrate.

[0157] Example Embodiment 15: The solar cell of Example Embodiment 14, wherein the conductive contacts are provided through openings in the bottom passivation and capping layers on the back surface of the substrate.

[0158] Exemplary embodiment 16: A method of manufacturing a solar cell includes forming an emitter region in a substrate, the emitter region being at a light receiving surface of the substrate. The method also includes forming a groove in the emitter region. The method also includes forming a passivation layer on the light receiving surface of the substrate and in the groove to passivate the emitter edge. The method also includes cutting the substrate to form a solar cell having a sidewall and an emitter region, the emitter region having a sidewall that is laterally retracted from the sidewall of the solar cell.

[0159] Exemplary Embodiment 17: The method of Exemplary Embodiment 16, wherein cutting the substrate includes cutting through the passivation layer in the trench.

[0160] Example Embodiment 18: The method of Example Embodiment 16, wherein cutting the substrate includes cutting a portion of the emitter region through laterally adjacent trenches.

[0161] Example Embodiment 19: The method of Example Embodiment 16, 17, or 18, wherein the grooves are formed using laser ablation.

[0162] Exemplary Embodiment 20: The method of Exemplary Embodiment 16, 17, or 18, wherein the grooves are formed using an etching paste delivered by screen printing or ink jetting.

Claims

1. A solar cell comprising: a substrate having a light receiving surface, a back surface, and sidewalls, wherein the light receiving surface is textured; an emitter region on the substrate, the emitter region being at the light receiving surface of the substrate, the emitter region having sidewalls that are laterally retracted from the sidewalls of the substrate; as well as a passivation layer on the sidewalls of the emitter region, wherein the laterally retracted sidewalls of the emitter region are parallel to the sidewalls of the passivation layer, wherein the passivation layer is in a corresponding groove between a corresponding sidewall of the emitter region and a corresponding sidewall of the substrate, and an isolated portion of the emitter region remains as the passivation layer laterally adjacent to a periphery of the solar cell, and The solar cell is formed by cutting the substrate, wherein cutting the substrate includes cutting through a portion of the emitter region laterally adjacent to the trench.

2. The solar cell according to claim 1, further comprising: A passivation layer on the light receiving surface of the substrate, wherein the passivation layer on the sidewall of the emitter region is continuous with the passivation layer on the light receiving surface of the substrate. 3 . The solar cell according to claim 2 , wherein the passivation layer on the light receiving surface of the substrate and the passivation layer on the sidewall of the emitter region include silicon oxide (SiOx) and silicon nitride (SiNx).

4. The solar cell according to claim 1, wherein the emitter region contains a dopant of a certain concentration of conductivity type, and the solar cell further comprises: A conductive type dopant region within the emitter region, wherein a concentration of dopant of the conductive type in the conductive type dopant region is higher than a concentration of dopant of the conductive type in the emitter region.

5. The solar cell according to claim 4, wherein the conductivity type is n-type, and the dopant is selected from the group consisting of: phosphorus dopants and arsenic dopants.

6. The solar cell according to claim 4, further comprising: A conductive contact is electrically connected to a dopant region of the conductivity type within the emitter region.

7. The solar cell of claim 6, wherein the conductive contacts are screen printed and fired through a passivation layer on the light receiving surface of the substrate.

8. The solar cell of claim 6, wherein the conductive contacts comprise silver.

9. The solar cell according to claim 1, wherein the substrate is a p-type single crystal silicon substrate.

10. The solar cell according to claim 1, wherein the emitter region comprises an n-type dopant, the solar cell further comprising: A p-type dopant region at the back surface of the substrate.

11. The solar cell according to claim 10, further comprising: A conductive contact is electrically connected to the p-type dopant region at the back surface of the substrate.

12. The solar cell of claim 11, wherein the conductive contacts are provided through openings in bottom passivation and capping layers on the back surface of the substrate.

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