Unit cell, solar cell including the same, and method for manufacturing the solar cell

Abstract

The present invention relates to a solar cell including a first unit cell manufactured using one of a plurality of pieces formed by separating a mother substrate, and a second unit cell coupled to the first unit cell, wherein the first unit cell includes a first cell electrode formed on the first unit substrate and having conductivity, and the second unit cell includes a second cell electrode formed on the second unit substrate and having conductivity, and the second cell electrode and the first cell electrode are bonded to each other without a bonding material to combine the second unit cell and the first unit cell, a unit cell included therein, and a method for manufacturing the solar cell.

Description

[Technical field]

[0001] The present invention relates to a solar cell, and more particularly to a solar cell that combines a substrate type solar cell and a thin-film type solar cell. [Background technology]

[0002] A solar cell is a device that uses the properties of semiconductors to convert light energy into electrical energy.

[0003] Solar cells have a PN junction structure in which a P (positive) type semiconductor and an N (negative) type semiconductor are joined together. When sunlight is incident on a solar cell with this structure, holes and electrons are generated in the semiconductor due to the energy of the incident sunlight. At this time, the holes (+) move toward the P-type semiconductor and the electrons (-) move toward the N-type semiconductor due to the electric field generated at the PN junction, generating an electric potential and allowing electricity to be produced.

[0004] Such solar cells can generally be classified into substrate type solar cells and thin film type solar cells.

[0005] The substrate-type solar cell is a solar cell manufactured by using a semiconductor material such as a silicon wafer as a substrate, and the thin-film type solar cell is a solar cell manufactured by forming a semiconductor in the form of a thin film on a substrate such as glass.

[0006] The substrate type solar cell has an advantage of being more efficient than the thin-film solar cell, and the thin-film solar cell has an advantage of being less expensive to manufacture than the substrate type solar cell.

[0007] In view of this, a solar cell that combines the substrate type solar cell and the thin film type solar cell has been proposed. A conventional solar cell will be described below with reference to the drawings.

[0008] A conventional method for manufacturing a solar cell includes the following steps.

[0009] First, a process of preparing a substrate having a plurality of separation portions formed thereon is performed, the separation portions being for separating the substrate into a plurality of pieces.

[0010] Next, a step of forming a one-surface electrode on one surface of the substrate is performed, and the one-surface electrode is cured.

[0011] Next, a process of forming an electrode on the other side of the substrate is performed, and the electrode is cured, thereby completing a mother substrate on which the electrode on one side and the electrode on the other side are formed.

[0012] Next, a bonding material is sprayed onto the second electrode, the bonding material being a material having a bonding strength capable of bonding the separated pieces together.

[0013] Next, a process of separating the substrate into a plurality of pieces is performed via a separating unit, whereby the substrate can be separated into a plurality of unit cells.

[0014] Next, a step of bonding the plurality of unit cells with a bonding material is performed, and the bonded unit cells are cured, thereby completing the manufacture of a solar cell.

[0015] Here, in the conventional solar cell, the unit cells are bonded to each other via the bonding material, and thus, the generated power must pass through the bonding material while flowing through the unit cells, which causes a problem in that the power generation efficiency of the solar cell is reduced due to the resistance of the bonding material itself. Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention has been devised to solve the above-mentioned problems, and relates to a unit cell that can reduce the degree to which the power generation efficiency of a solar cell is reduced due to the resistance of a bonding material itself, a solar cell including the same, and a method for manufacturing the solar cell. [Means for solving the problem]

[0017] In order to solve the above-mentioned problems, the present invention can include the following configurations.

[0018] The method for manufacturing a solar cell according to the present invention includes a substrate preparation step of preparing a substrate having a plurality of separation portions for separating the substrate into a plurality of pieces; a first electrode formation step of forming a plurality of first bus electrodes having electrical conductivity on one side of the substrate; a second electrode formation step of forming a plurality of uncured second bus electrodes having electrical conductivity on the other side of the substrate; a separation step of forming a plurality of unit cells by separating the substrate into a plurality of pieces via the separation portions; and a joining step of joining the unit cells via the uncured second bus electrodes.

[0019] The solar cell according to the present invention may include a first unit cell manufactured using any one of a plurality of pieces formed by separating a mother substrate; and a second unit cell coupled to the first unit cell. The first unit cell may include a first cell electrode formed on the first unit substrate and having electrical conductivity. The second unit cell may include a second cell electrode formed on the second unit substrate and having electrical conductivity. The second cell electrode and the first cell electrode may be bonded to each other without a bonding material, thereby coupling the second unit cell to the first unit cell.

[0020] The solar cell according to the present invention may include a first unit cell manufactured using any one of a plurality of pieces formed by separating a mother substrate; and a second unit cell connected to the first unit cell. The first unit cell may include a first cell electrode formed on the first unit substrate and having electrical conductivity. The second unit cell may include a second cell electrode formed on the second unit substrate and having electrical conductivity. The second cell electrode and the first cell electrode may be bonded to each other to combine the second unit cell and the first unit cell.

[0021] A unit cell according to the present invention may include a unit substrate manufactured using any one of a plurality of pieces formed by separating a mother substrate; and a conductive cell electrode formed on the unit substrate. The cell electrode may include a lower cell electrode and an upper cell electrode formed on one side and the other side of the unit substrate, respectively. Either the upper cell electrode or the lower cell electrode may be formed in an uncured state. Effect of the Invention

[0022] According to the present invention, the following effects can be obtained.

[0023] The present invention is embodied in such a way that a series of processes for spraying a bonding material can be omitted, thereby shortening the manufacturing time of a solar cell.

[0024] The present invention is implemented to fundamentally prevent a decrease in power generation efficiency of a solar cell due to the resistance of the junction material itself, thereby improving the quality of the completed solar cell. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic front view of a solar cell according to the present invention; [Diagram 2] FIG. 2 is a schematic front view of a unit cell according to the present invention. [Diagram 3] 2 is a schematic front view showing a state in which a first unit cell and a second unit cell are combined in a solar cell according to the present invention; FIG. [Figure 4] FIG. 2 is a schematic front view showing a state before a first unit cell and a second unit cell are combined in an example of a solar cell according to the present invention. [Diagram 5] FIG. 2 is a schematic front view showing a state after a first unit cell and a second unit cell are combined in an example of a solar cell according to the present invention. [Figure 6] 3 is a schematic perspective view showing a first bonding electrode and a first unbonded electrode formed on a first upper cell electrode in the solar cell according to the present invention; FIG. [Figure 7] 4 is a schematic perspective view showing a second bonding electrode and a second unbonded electrode formed on a second lower cell electrode in the solar cell according to the present invention; FIG. [Figure 8] 4 is a schematic front view showing a state before a second bonding electrode is bonded to a first bonding electrode in a solar cell according to the present invention. FIG. [Figure 9] 10 is a schematic front view showing how an insertion member is inserted into an insertion groove as a result of a second bonding electrode being bonded to a first bonding electrode in a solar cell according to the present invention. FIG. [Figure 10a] 3 is a schematic front view showing a substrate preparation step in the solar cell manufacturing method according to the present invention; FIG. [Figure 10b] 3 is a schematic front view showing a first electrode forming step in the manufacturing method of the solar cell according to the present invention. FIG. [Figure 10c] 2 is a schematic front view showing a first curing step of the method for manufacturing a solar cell according to the present invention. FIG. [Figure 10d] 3 is a schematic front view showing a second electrode forming step in the manufacturing method of the solar cell according to the present invention. FIG. [Figure 10e] 3A to 3C are schematic front views showing a separation process of the solar cell manufacturing method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The advantages and features of the present invention, as well as the methods for achieving them, will become clear from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be realized in various different forms. The embodiments are provided merely to complete the disclosure of the present invention and to fully inform those skilled in the art of the present invention of the scope of the invention. The present invention is defined only by the scope of the claims.

[0027] In order to explain the embodiments of the present invention, the shapes, sizes, ratios, angles, numbers, etc. shown in the drawings are illustrative, and the present invention is not limited to the matters shown in the drawings. The same reference symbols refer to the same components throughout the specification. In addition, in explaining the present invention, if a specific description of related known technology is judged to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When "including," "having," "consisting of," etc. are used in the present specification, other parts can be added unless "only" is used. When a component is expressed in the singular, it includes the case where it includes a plural, unless otherwise expressly stated.

[0028] When interpreting elements, they are interpreted as including a margin of error unless otherwise expressly stated.

[0029] When describing a positional relationship, for example when the positional relationship of two parts is described using "above", "at the top", "below", "beside", etc., one or more other parts may be located between the two parts, unless "immediately" or "directly" is used.

[0030] When describing a temporal relationship, for example when the temporal sequence is described using "after", "following", "next to", "before", etc., it can also include cases where the events are not consecutive, since "immediately" or "directly" are not used.

[0031] Although the terms "first", "second" and the like are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, the first component referred to below may be the second component within the technical concept of the present invention.

[0032] The features of the various embodiments of the present invention may be partially or fully combined or combined with each other, and various technical interlocking and driving mechanisms may be possible, and each embodiment may be implemented independently of each other, or may be implemented together in a related relationship.

[0033] Hereinafter, an embodiment of a solar cell 1 according to the present invention will be described in detail with reference to the accompanying drawings. A unit cell 10 according to the present invention is included in the solar cell 1 according to the present invention, and will be described together with the embodiment of the solar cell 1 according to the present invention. Note that the hatching and dots shown in Figs. 1 to 10e do not indicate cross sections but are shown to distinguish the configurations.

[0034] Referring to Fig. 1, a solar cell 1 according to the present invention converts light energy of sunlight into electrical energy. The solar cell 1 according to the present invention can be realized as a substrate type solar cell or a thin film type solar cell. Hereinafter, the solar cell 1 according to the present invention will be described on the basis that it is realized as a substrate type solar cell, but it will be obvious to those skilled in the art to which the present invention pertains that the solar cell 1 according to the present invention can be realized as a thin film solar cell from this.

[0035] Referring to FIG. 1, the solar cell 1 according to the present invention may be manufactured in the form of a module in which a plurality of unit cells 10 are joined together. Each of the unit cells 10 is manufactured using any one of a plurality of pieces formed by separating a mother substrate 100 (as shown in FIG. 10d). The mother substrate 100 may be in a state before being separated into the unit cells 10 in the solar cell 1 according to the present invention. The mother substrate 100 includes a substrate 110 (as shown in FIG. 10a), a first bus electrode 130 (as shown in FIG. 10b) formed on one surface 110a of the substrate 110, and a second bus electrode 140 (as shown in FIG. 10d) formed on the other surface 110b of the substrate 110. Although FIG. 1 shows that the solar cell 1 according to the present invention includes five unit cells 10, 10', 10'', 10'''', and 10'''', this is merely an example, and the solar cell 1 according to the present invention may include two to four unit cells 10, or six or more unit cells 10. Each of the unit cells 10 may be embodied generally identically to one another, except for the location in which they are disposed.

[0036] Referring to FIGS. 1 and 2, each of the unit cells 10 may include a unit substrate 11 and a cell electrode 12 .

[0037] The unit substrates 11 may be formed by separating the mother substrate 100 (shown in FIG. 10d). The unit substrates 11 may have a predetermined electrical conductivity polarity. The number of unit substrates 11 may be equal to the number of pieces formed by separating one mother substrate 100. For example, when the mother substrate 100 is separated into five pieces, five unit substrates 11 may be formed. The unit substrates 11 may be a part of the substrate 110 (shown in FIG. 10a).

[0038] The cell electrodes 12 are formed on the unit substrates 11. The cell electrodes 12 may be conductive and may be made of a metal material having excellent conductivity, such as Ag, Al, Ag+Al, Ag+Mg, Ag+Mn, Ag+Sb, Ag+Zn, Ag+Mo, Ag+Ni, Ag+Cu, Ag+Al+Zn, etc.

[0039] The cell electrodes 12 may include a lower cell electrode 121 and an upper cell electrode 122 .

[0040] The lower cell electrode 121 is formed on one surface 11a of the unit substrate 11. The one surface 11a of the unit substrate 11 may be a surface of the unit substrate 11 facing a downward direction in which the height of the solar cell 1 according to the present invention is generally decreased. The one surface 11a of the unit substrate 11 may be a surface of the unit substrate 11 facing an upward direction opposite to the downward direction. The lower cell electrode 121 may be a part of the first bus electrode 130 (shown in FIG. 10b).

[0041] The upper cell electrode 122 is formed on the other surface 11b of the unit substrate 11. When the one surface 11a of the unit substrate 11 is the surface of the unit substrate 11 facing the downward direction, the other surface 11b of the unit substrate 11 may be the surface of the unit substrate 11 facing the upward direction. Hereinafter, the "one surface" and the "other surface" will be described based on the surface of a specific configuration facing the downward direction and the upper direction, respectively. In addition, it will be apparent to those skilled in the art to which the present invention pertains that the terms "upper side" and "lower side" described in this specification are used to distinguish each configuration and do not refer to a specific direction. The upper cell electrode 122 may be a part of the second bus electrode 140 (shown in FIG. 10d).

[0042] At least one of the upper cell electrode 122 and the lower cell electrode 121 may be formed in a pre-cured state (PC). As a result, the solar cell 1 according to the present invention may realize an adhesive force for bonding the unit cells 10 through the electrodes in the pre-cured state (PC). The pre-cured state (PC) is a state in which the electrodes have an adhesive force. The electrodes 121 and 122 may have fluidity in the pre-cured state (PC). When one of the upper cell electrode 122 and the lower cell electrode 121 is in a pre-cured state (HC), the remaining electrode may be formed in the pre-cured state (PC). In this case, the solar cell 1 according to the present invention may realize an adhesive force for bonding the unit cells 10 through the electrodes in the pre-cured state (PC). The pre-cured state (HC) is a state in which the electrodes do not have an adhesive force. The electrodes 121 and 122 may not have fluidity in the pre-cured state (HC) and may have a certain shape.

[0043] 3 to 9, a solar cell 1 according to the present invention may include a first unit cell 2 and a second unit cell 3. The first unit cell 2 and the second unit cell 3 may be arranged in a substantially rectangular shape.

[0044] The first unit cell 2 may be any one of the unit cells 10. The first unit cell 2 is manufactured using any one of a plurality of pieces formed by separating the mother substrate 100. Electricity generated by the solar cell 1 according to the present invention may be transferred to the second unit cell 3 through the first unit cell 2.

[0045] Referring to FIG. 3, the first unit cell 2 may include the first unit substrate 21 and a first cell electrode 22 .

[0046] The first unit substrates 21 may be a part of the substrate 110 (shown in FIG. 10a). The first unit substrates 21 may be formed by separating the mother substrate 100. The first unit substrates 21 may have a predetermined electrical conductivity polarity.

[0047] The first cell electrodes 22 are formed on the first unit substrate 21. The first cell electrodes 22 may be formed on each of one surface 21a and the other surface 21b of the first unit substrate 21. The first cell electrodes 22 may be conductive. The first cell electrodes 22 may be formed of the same material, such as Ag, Al, Ag+Al, Ag+Mg, Ag+Mn, Ag+Sb, Ag+Zn, Ag+Mo, Ag+Ni, Ag+Cu, Ag+Al+Zn, or the like.

[0048] The first cell electrode 22 may include a first lower cell electrode 221 and a first upper cell electrode 222 .

[0049] The first lower cell electrode 221 is formed on one surface 21a of the first unit substrate 21. The first lower cell electrode 221 may be formed on one surface 21a of the first unit substrate 21 arranged to face the downward direction. The first lower cell electrode 221 may be a part of the first bus electrode 130 (shown in FIG. 10b). The first lower cell electrode 221 may be formed in any one of the hardened state (HC) or the unhardened state (PC).

[0050] The first upper cell electrode 222 is formed on the other surface 21b of the first unit substrate 21. The first upper cell electrode 222 may be formed on the other surface 21b of the first unit substrate 21 arranged to face the upward direction. The first upper cell electrode 222 may be a part of the second bus electrode 140 (shown in FIG. 10d). The first upper cell electrode 222 may be formed in a state different from that of the first lower cell electrode. For example, when the first lower cell electrode 221 is in the hardened state (HC), the first upper cell electrode 222 may be formed in the unhardened state (PC). When the first lower cell electrode 221 is in the unhardened state (PC), the first upper cell electrode 222 may also be formed in the hardened state (HC).

[0051] The second unit cell 3 may be any one of the unit cells 10 coupled to the first unit cell 2. The second unit cell 3 may be coupled to the upper side of the first unit cell 2. The second unit cell 3 is manufactured using any one of a plurality of pieces formed by separating the mother substrate 100.

[0052] The second unit cell 3 may include a second unit substrate 31 and a second cell electrode 32 .

[0053] The second unit substrates 31 may be a part of the substrate 110 (shown in FIG. 1A). The second unit substrates 31 may be formed by separating the mother substrate 100 (shown in FIG. 1C). The second unit substrates 31 may have a predetermined electrical conductivity polarity.

[0054] The second cell electrodes 32 are formed on the second unit substrate 31. The second cell electrodes 32 may be formed on each of one surface 31a and the other surface 31b of the second unit substrate 31. The second cell electrodes 32 may be conductive. The second cell electrodes 32 may be formed of the same material, such as Ag, Al, Ag+Al, Ag+Mg, Ag+Mn, Ag+Sb, Ag+Zn, Ag+Mo, Ag+Ni, Ag+Cu, Ag+Al+Zn, or the like.

[0055] The second cell electrode 32 and the first cell electrode 22 can be bonded to each other without a bonding material, thereby bonding the second unit cell 3 and the first unit cell 2. That is, the second cell electrode 32 and the first cell electrode 22 can be bonded to each other, thereby bonding the second unit cell 3 and the first unit cell 2. As a result, the solar cell 1 according to the present invention can achieve the following effects.

[0056] First, the solar cell 1 according to the present invention is embodied so that the unit cells 2 and 3 can be bonded together via the cell electrodes 22 and 32. As a result, compared to the conventional technology in which the unit cells 10 are bonded together using a bonding material, the solar cell 1 according to the present invention can omit a series of steps of injecting a bonding material during the process of manufacturing the solar cell. Therefore, the solar cell 1 according to the present invention can increase the mass productivity of solar cells by shortening the time required for manufacturing the solar cell.

[0057] Secondly, the solar cell 1 according to the present invention is embodied such that the generated power does not need to move through the bonding material by bonding the unit cells 2 and 3 without the bonding material. As a result, the solar cell 1 according to the present invention can fundamentally prevent the power generation efficiency of the solar cell from decreasing due to the resistance of the bonding material itself, thereby improving the quality of the completed solar cell.

[0058] The second cell electrode 32 and the first cell electrode 22 may both be formed of the same material and joined to each other. For example, the second cell electrode 32 and the first cell electrode 22 may both be formed of Ag material. Therefore, the solar cell 1 according to the present invention is embodied to be able to reduce internal resistance. This is because, when power moves between the first cell electrode 22 and the second cell electrode 32, the resistance is further reduced when the power moves between the same material compared to when the power moves between different materials. Therefore, the solar cell 1 according to the present invention can further increase the solar cell power generation efficiency.

[0059] The second cell electrode 32 may include a second lower cell electrode 321 and a second upper cell electrode 322 .

[0060] The second lower cell electrode 321 is formed on one surface 31a of the second unit substrate 31. The second lower cell electrode 321 may be formed on one surface 31a of the second unit substrate 31 arranged to face the downward direction. The second lower cell electrode 321 may be a partial electrode of the first bus electrode 130. The second lower cell electrode 321 may be formed in any one of the hardened state (HC) or the unhardened state (PC).

[0061] The second upper cell electrode 322 is formed on the other surface 31b of the second unit substrate 31. The second upper cell electrode 322 may be formed on the other surface 31b of the second unit substrate 31 to face the upward direction. The second upper cell electrode 322 may be a part of the second bus electrode 140. When the second lower cell electrode 321 is in the hardened state (HC), the second upper cell electrode 322 may be formed in the unhardened state (PC). When the second lower cell electrode 321 is in the unhardened state (PC), the second upper cell electrode 322 may be formed in the hardened state (HC).

[0062] 3, the solar cell 1 according to the present invention is embodied such that the second unit cell 3 and the first unit cell 2 are combined by bonding the second lower cell electrode 321 and the first upper cell electrode 222 to each other. Hereinafter, a description will be given based on the second unit cell 3 and the first unit cell 2 being combined by bonding the second lower cell electrode 321 and the first upper cell electrode 222 to each other, however, this is merely an example, and the second unit cell 3 and the first unit cell 2 may also be combined by bonding the second upper cell electrode 322 and the first lower cell electrode 221 to each other.

[0063] At least one of the second lower cell electrode 321 and the first upper cell electrode 222 may be formed in the uncured state (PC). Thus, the solar cell 1 according to the present invention may realize a bonding force for bonding the unit cells 2 and 3. For example, the second lower cell electrode 321 and the first upper cell electrode 222 may both be formed in the uncured state (PC) to bond the second unit cell 3 and the first unit cell 2. When at least one of the second lower cell electrode 321 and the first upper cell electrode 222 is formed in the uncured state (PC), the remaining electrode may be formed in the cured state (HC) to bond the second unit cell 3 and the first unit cell 2.

[0064] 4 and 5, the first upper cell electrode 222 may be formed in the uncured state (PC) and may be bonded to the second lower cell electrode 321 to reduce its thickness. Thus, the solar cell 1 according to the present invention may reduce the overall thickness, thereby reducing the distance that the generated power travels. Thus, the solar cell 1 according to the present invention may be embodied to reduce its overall resistance. The thickness may correspond to a direction parallel to each of the upper direction and the lower direction, and may be a length based on a first axis direction (X-axis direction) corresponding to the same direction as the direction in which the second unit cell 3 and the first unit cell 2 are spaced apart. Although not shown in the figures, the second lower cell electrode 321 may also be formed in the uncured state (PC) and may be bonded to the first upper cell electrode 222 to reduce its thickness. The second lower cell electrode 321 and the first upper cell electrode 222 may be bonded to each other to have the same thickness.

[0065] For example, as shown in FIG. 4 and FIG. 5, when the first upper cell electrode 222 is formed to have a first thickness (D1) and the second lower cell electrode 321 is formed to have a second thickness (D2), a third thickness (D3) formed by bonding the second lower cell electrode 321 and the first upper cell electrode 222 to each other may have a value smaller than the sum of the first thickness (D1) and the second thickness (D2). This is because at least one of the first upper cell electrode 222 and the second lower cell electrode 321 is formed in the uncured state (PC). As a result, the solar cell 1 according to the present invention may be embodied to have a reduced overall thickness. The third thickness (D3) may be a distance between the second unit cell 3 and the first unit cell 2 based on the first axis direction (X-axis direction). In FIG. 4, the first upper cell electrode 222 is shown to be formed in the uncured state (PC), however this is exemplary and the second lower cell electrode 321 may also be formed in the uncured state (PC) and the third thickness (D3) may be reduced.

[0066] When at least one of the second lower cell electrode 321 and the first upper cell electrode 222 is formed in the uncured state (PC), the second lower cell electrode 321 and the first upper cell electrode 222 may be disposed to partially overlap each other based on the first axis direction (X-axis direction) as shown in Fig. 5. Therefore, the overall thickness of the solar cell 1 according to the present invention can be reduced.

[0067] Hereinafter, an embodiment of a pattern of the first upper cell electrode 222 and the second lower cell electrode 321 will be described with reference to the accompanying drawings. When the second unit cell 3 and the first unit cell 2 are combined by bonding the second upper cell electrode 322 and the first lower cell electrode 221 to each other, the first lower cell electrode 221 may be embodied in a substantially similar manner to the second lower cell electrode 321 described below, and the second upper cell electrode 322 may be embodied in a substantially similar manner to the first upper cell electrode 222.

[0068] Referring to FIG. 6, the first upper cell electrode 222 may include a first connecting electrode 2221 .

[0069] The second lower cell electrode 321 is bonded to the first bonding electrode 2221. The first bonding electrode 2221 may be a portion of the first upper cell electrode 222 to which the second lower cell electrode 321 is bonded. The first bonding electrode 2221 may be bonded to the first unit substrate 21. The first bonding electrode 2221 may be formed in the hardened state (HC).

[0070] The first bonding electrode 2221 may include a first bonding surface 1A and an insertion groove (G).

[0071] The first bonding surface 1A (shown in FIG. 8) may be one surface of the first bonding electrode 2221 facing the second lower cell electrode 321. In this case, the other surface of the first bonding electrode 2221 may face the first unit substrate 21. The second lower cell electrode 321 may be bonded to the first bonding surface 1A.

[0072] The insertion groove (G) is formed on the first bonding surface 1A. The insertion groove (G) may be formed by machining a groove (groove) of a predetermined depth from the first bonding surface 1A. The insertion groove (G) may be formed to have the same size as the first upper cell electrode 222 based on the first axis direction (X-axis direction). Although FIG. 6 shows that 14 insertion grooves (G) are formed on the first bonding surface 1A, this is merely an example, and 1 to 13 or 15 or more insertion grooves (G) may be formed on the first bonding surface 1A.

[0073] Referring to FIG. 6, the first bonding electrode 2221 may include a first bonding finger bar 1F.

[0074] The first bonding finger bar 1F may have a function of transferring power generated in the first unit substrate 21 to the second lower cell electrode 321. The first bonding finger bar 1F is formed with the insertion groove (G) on the inside. The first bonding finger bar 1F may include a first bonding finger member formed along a second axis direction (Y axis direction) and a second bonding finger member formed along a third axis direction (Z axis direction) perpendicular to the second axis direction (Y axis direction). The second bonding finger member and the first bonding finger member may be coupled to each other. The second bonding finger member and the first bonding finger member may be arranged to surround the insertion groove (G). For example, two second bonding finger members and two first bonding finger members may be arranged outside the insertion groove (G). One second bonding finger member and two first bonding finger members may also be arranged outside the insertion groove (G). 6 illustrates three first joint finger members and twelve second joint finger members. The second axis direction (Y axis direction) may be perpendicular to the first axis direction (X axis direction). The third axis direction (Z axis direction) may be perpendicular to both the second axis direction (Y axis direction) and the first axis direction (X axis direction).

[0075] Referring to FIG. 6, the first upper cell electrode 222 may include a first unbonded electrode 2222 .

[0076] The first unbonded electrode 2222 is coupled to the first bonded electrode 2221. The first unbonded electrode 2222 may be coupled to the first bonded electrode 2221 to transfer power generated in the first unit substrate 21 to the first bonded electrode 2221. The first unbonded electrode 2222 may be a part of the first upper cell electrode 222 to which the second lower cell electrode 321 is not coupled. The first unbonded electrode 2222 may be coupled to the first unit substrate 21. The first unbonded electrode 2222 may be formed in the same hardened state (HC) as the first bonded electrode 2221.

[0077] The first unjoined electrode 2222 may include a plurality of first unjoined finger bars 10F spaced apart from each other. The first unjoined finger bars 10F may be spaced apart from each other with respect to the second axis direction (Y-axis direction). The first unjoined finger bars 10F may be formed to extend along the third axis direction (Z-axis direction). The first unjoined finger bars 10F may be formed to have a linear shape in the third axis direction (Z-axis direction). The first unjoined finger bars 10F may be joined to the first joined electrode 2221. The first unjoined finger bars 10F may transfer the generated power to the first joined electrode 2221. FIG. 6 shows three first unjoined finger bars 10F.

[0078] 7 to 9, the second lower cell electrode 321 may include a second connecting electrode 3211.

[0079] The second bonding electrode 3211 is bonded to the first bonding electrode 2221. The second bonding electrode 3211 may be a portion of a second lower cell electrode 321 bonded to the first bonding electrode 2221. The second bonding electrode 3211 may be bonded to the second unit substrate 31. The second bonding electrode 3211 may be formed in the uncured state (PC).

[0080] 7 and 8, the second bonding electrode 3211 may include a second bonding surface 2A.

[0081] The second bonding surface 2A may be one surface of the second bonding electrode 3211 facing the first upper cell electrode 222. The other surface of the second bonding electrode 3211 may face the second unit substrate 31. The second bonding surface 2A may be bonded to the first bonding electrode 2221. The second bonding surface 2A may be formed to have a flat planar shape before the second bonding electrode 3211 and the first bonding electrode 2221 are bonded to each other. That is, the second bonding surface 2A may be formed in a flat shape without bending before the second bonding electrode 3211 and the first bonding electrode 2221 are bonded to each other.

[0082] Referring to FIG. 9, the second connecting electrode 3211 may include an insert member (I).

[0083] The insertion member (I) is inserted into the insertion groove (G) by bonding the second bonding electrode 3211 to the first bonding electrode 2221. Thus, the solar cell 1 according to the present invention can be embodied so that the second bonding electrode 3211 can be supported by the first bonding electrode 2221. Therefore, the solar cell 1 according to the present invention can increase the bonding strength between the first unit cell 2 and the second unit cell 3 by improving the bonding strength between the second bonding electrode 3211 and the first bonding electrode 2221. The insertion member (I) can be formed in the uncured state (PC) and inserted into the insertion member (I). The insertion member (I) can be formed in a shape corresponding to the insertion groove (G). The second bonding electrode 3211 can include the same number of the insertion members (I) as the number of the insertion grooves (G).

[0084] In the above description, the first bonding electrode 2221 includes the insertion groove (G) and the second bonding electrode 3211 includes the insertion member (I), but this is only an example. From this, it will be clear to a person skilled in the art to which the present invention pertains that the first bonding electrode 2221 includes the insertion member (I) and the second bonding electrode 3211 includes the insertion groove (G).

[0085] 7 to 9, the second lower cell electrode 321 may include a second unbonded electrode 3212.

[0086] The second unbonded electrode 3212 is coupled to the second bonded electrode 3211. The second unbonded electrode 3212 may be coupled to the second bonded electrode 3211 to transfer power generated in the second unit substrate 31. The second unbonded electrode 3212 may be a part of the second lower cell electrode 321 that is not coupled to the first upper cell electrode 222. The second unbonded electrode 3212 may be coupled to the second unit substrate 31. The second unbonded electrode 3212 may be formed in the uncured state (PC) of the same shape as the second bonded electrode 3211.

[0087] The second unjoined electrode 3212 may include a plurality of second unjoined finger bars 20F spaced apart from each other. The second unjoined finger bars 20F may be spaced apart from each other based on the second axis direction (Y-axis direction). The second unjoined finger bars 20F may be formed extending along the third axis direction (Z-axis direction). The second unjoined finger bars 20F may be joined to the second joining electrode 3211. The second unjoined finger bars 20F may have a function of transferring power generated in the second unit substrate 31. FIG. 7 shows three second unjoined finger bars 20F.

[0088] Hereinafter, an embodiment of the method for manufacturing a solar cell according to the present invention will be described in detail with reference to the accompanying drawings. The method for manufacturing a solar cell according to the present invention is for manufacturing a solar cell 1 according to the present invention.

[0089] Referring to FIG. 10a, a method for manufacturing a solar cell according to the present invention may include a substrate preparation step.

[0090] The substrate preparation process is a process of preparing the substrate 110 having a plurality of separation portions 120 formed thereon for separating the substrate 110 into a plurality of pieces (portions). The substrate preparation process can be performed by a substrate loading device (not shown) that loads the substrate 110 into a processing space (not shown) for manufacturing a solar cell. The processing space can accommodate manufacturing equipment required for manufacturing a solar cell therein and can be realized as a chamber as a whole.

[0091] The substrate 110 may have a predetermined electrical conductivity polarity. For example, the substrate 110 may be an N-type silicon wafer or a P-type silicon wafer. Although not shown in the figure, one surface 110a of the substrate 110 may have an uneven structure. The substrate 110 may include a lower surface of the substrate arranged to face the downward direction, an upper surface of the substrate arranged to face the upward direction, and a side surface 110c of the substrate connected to each of the lower surface and the upper surface of the substrate 110. In this case, the one surface 110a of the substrate 110 may correspond to any one of the lower surface of the substrate 110, the upper surface of the substrate 110, or the side surface 110c of the substrate 110. For example, when the one surface 110a of the substrate 110 corresponds to the lower surface of the substrate 110, the other surface 110b of the substrate 110 may correspond to the upper surface of the substrate 110. In this case, each of the thin film layers formed on one surface 110a of the substrate 110 and the other surface 110b of the substrate 110 may also have an uneven structure.

[0092] The separation portion 120 is for separating the substrate 110 into a plurality of pieces. The separation portion 120 may be formed on one surface 110a of the substrate 110. The separation portion 120 may be formed through a scribing process for processing a groove at a predetermined depth from the one surface 110a of the substrate 110. The scribing process may be performed by a scribing device (not shown) that irradiates a laser toward the substrate 110 to remove a predetermined region of the substrate 110. Although FIG. 10a shows that the scribing process is performed on the one surface 110a of the substrate 110, this is an example, and the scribing process may also be performed on the other surface 110b of the substrate 110. In addition, in this specification, the separation portion 120 is described based on the case where the separation portion 120 is formed through the scribing process, but this is an example, and the separation portion 120 may also be formed by a method of immersing the substrate 110 in an etching bath (not shown) or a process using dry etching, a mask, etc. If it is desired to separate the substrate 110 into five pieces, four separation portions 120 may be formed on one surface 110a of the substrate 110 as shown in FIG. 10a.

[0093] Although not shown, one or more thin film layers may be formed on the substrate 110. An example of the thin film layers formed on the substrate 110 will be described below.

[0094] First, a first thin film layer may be formed on the substrate 110. The process of forming the first thin film layer may be performed after the scribing process. The first thin film layer may be a semiconductor layer formed in the form of a thin film on the substrate 110. The first thin film layer may form a PN junction with the substrate 110. Therefore, when the substrate 110 is an N-type silicon wafer, the first thin film layer may be a P-type semiconductor layer. The first thin film layer may be formed using a CVD (Chemical Vapor Deposition) process or the like. The first thin film layer may be formed in a PIN structure in which a P-type semiconductor material, an I-type semiconductor material, and an N-type semiconductor material are sequentially stacked. When the first thin film layer is formed in a PIN structure, the I-type semiconductor material is depleted by the P-type semiconductor material and the N-type semiconductor material, generating an electric field inside, and holes and electrons generated by sunlight are drifted by the electric field and collected from the P-type semiconductor material and the N-type semiconductor material, respectively. Meanwhile, when the first thin film layer is formed in a PIN structure, it is preferable to form a P-type semiconductor material on the first thin film layer, followed by forming an I-type semiconductor material and an N-type semiconductor material. This is because the drift mobility of holes is generally lower than that of electrons, and therefore the P-type semiconductor material is formed close to the light receiving surface in order to maximize the collection efficiency of incident light. Meanwhile, in the method for manufacturing a solar cell according to the present invention, the first thin film layer may be formed to have a stacked structure. For example, in the method for manufacturing a solar cell according to the present invention, the first thin film layer may be formed to have a tandem (PIN / PIN) type or triple (PIN / PIN / PIN) type stacked structure. The first thin film layer may be formed on at least one of the first surface 110a, the second surface 110b, and the side surface of the substrate 110, or may be formed on each of the first surface 110a, the second surface 110b, and the side surface of the substrate 110.

[0095] Next, a second thin film layer is formed on the first thin film layer. The process of forming the second thin film layer can be performed after the process of forming the first thin film layer. The second thin film layer can be a transparent conductive layer. For example, the second thin film layer can be a TCO (Transparent Conductive Oxide) layer. The second thin film layer can protect the first thin film layer, collect carriers, such as holes (+), generated in the substrate 110, and move the collected carriers in the upward direction. The second thin film layer can be made of a transparent conductive material such as ITO (Indium Tin Oxide), ZnOH, ZnO:B, ZnO:Al, SnO2, or SnO2:F. The second thin film layer can be formed by using a sputtering method, an MOCVD method, or the like, of a transparent conductive material such as ZnO, ZnO:B, ZnO:Al, or Ag. The second thin film layer has a function of increasing the proportion of light re-entering the first thin film layer by scattering sunlight and causing it to travel at various angles.

[0096] Next, a third thin film layer is formed on the second thin film layer. The process of forming the third thin film layer may be performed after the process of forming the second thin film layer. When the third thin film layer is formed on the second thin film layer, the first thin film layer may be embodied as an intrinsic semiconductor layer, the second thin film layer as a semiconductor layer, and the third thin film layer as a transparent conductive layer. In this case, the multiple thin film layers may be formed using a plasma enhanced chemical vapor deposition (PECVD) method and a sputtering method.

[0097] The method for manufacturing a solar cell according to the present invention can selectively form the first thin film layer, the second thin film layer, and the third thin film layer. That is, the method for manufacturing a solar cell according to the present invention can form at least one layer among the first thin film layer, the second thin film layer, and the third thin film layer, and it is not necessary to form all of the first thin film layer, the second thin film layer, and the third thin film layer.

[0098] Referring to FIG. 10b, the method for manufacturing a solar cell according to the present invention may include a first electrode forming step.

[0099] The first electrode forming process is a process of forming a plurality of conductive first bus electrodes 130 on one surface 110a of the substrate 110. The first electrode forming process can be performed after the substrate preparation process. The first bus electrodes 130 formed by the first electrode forming process can be made of Ag, Al, Ag+Al, Ag+Mg, Ag+Mn, Ag+Sb, Ag+Zn, Ag+Mo, Ag+Ni, Ag+Cu, Ag+Al+Zn, or the like. In FIG. 10b, the first electrode forming process is shown to be formed on one surface 110a of the substrate 110, but this is merely an example, and the first electrode forming process can also be performed on the other surface 110b of the substrate 110.

[0100] Referring to FIG. 10c, the method for manufacturing a solar cell according to the present invention may include a first curing step.

[0101] The first curing process is a process of hardening the first bus electrode 130. The first curing process can be performed after the first electrode forming process. The first curing process can be performed by a heating device (not shown) that heats the first bus electrode 130. By performing the first curing process, the first bus electrode 130 can be formed in the hardened state (HC).

[0102] Referring to FIG. 10d, the method for manufacturing a solar cell according to the present invention may include a second electrode formation step.

[0103] The second electrode forming process is a process of forming a plurality of conductive second bus electrodes 140 in the uncured state (PC) on the other surface 110b of the substrate 110. The second electrode forming process can be performed after the first electrode forming process. The second bus electrodes 140 formed by performing the second electrode forming process can be made of materials such as Ag, Al, Ag+Al, Ag+Mg, Ag+Mn, Ag+Sb, Ag+Zn, Ag+Mo, Ag+Ni, Ag+Cu, Ag+Al+Zn, etc. Completion of the second electrode forming process allows the mother substrate 100 to be manufactured.

[0104] The method for manufacturing a solar cell according to the present invention is implemented so as not to include a process of curing the second bus electrode 140 after the second electrode forming process is performed. Therefore, the method for manufacturing a solar cell according to the present invention can implement a bonding force for bonding the unit cells 10 through the uncured (PC) second bus electrode 140.

[0105] Referring to FIG. 10e, the method for manufacturing a solar cell according to the present invention may include a separation step.

[0106] The separation process is a process of forming the unit cells 10 by separating the substrate 110 into a plurality of pieces through the separation unit 120. That is, the separation process is a process of forming a plurality of the unit cells 10 by separating the mother substrate 100 through the separation unit 120. The separation process can be performed by a separation device (not shown) that applies an external force such as a bending force to the mother substrate 100. The separation process can be performed after the second electrode forming process. When it is desired to separate the mother substrate 100 into N (N is an integer of 2 or more) unit cells 10, the separation process can be performed N-1 times. For example, as shown in FIG. 10e, when it is desired to separate the mother substrate 100 into five unit cells 10, the separation process can be performed four times.

[0107] Referring again to FIG. 1, the method for manufacturing a solar cell according to the present invention may include a bonding step.

[0108] The bonding process is a process of bonding the unit cells 10 via the second bus electrode 140 in the uncured state (PC). The bonding process can be performed by a bonding device (not shown) that moves and bonds the separated unit cells 10. The bonding process can be performed after the separation process. When the mother substrate 100 is separated into N unit cells 10, the bonding process can be performed N-1 times. For example, as shown in FIG. 10e, when the mother substrate 100 is separated into five unit cells 10, the bonding process can be performed four times.

[0109] Although not shown in the figure, the method for manufacturing a solar cell according to the present invention may further include a second curing step.

[0110] The second curing process is a process for hardening the bonded unit cells 10. The second curing process can be performed by the heating device. The second curing process can be performed after the bonding process. By performing the second curing process, the solar cell 1 according to the present invention, which is in a module form in which the unit cells 10 are bonded, can be manufactured.

[0111] The present invention described above is not limited to the above-mentioned embodiments and the attached drawings, and it will be apparent to those skilled in the art to which the present invention pertains that multiple substitutions, modifications and alterations are possible within the scope of the technical idea of ​​the present invention.

Claims

1. a substrate preparation step of preparing a substrate having a plurality of separation portions formed thereon for separating the substrate into a plurality of pieces; a first electrode forming step of forming a plurality of first bus electrodes having electrical conductivity on one surface of the substrate; a first curing step of hardening the first bus electrode; a second electrode forming step of forming a plurality of uncured conductive second bus electrodes on the other surface of the substrate; a separating step of separating the substrate into a plurality of pieces through the separating portion to form a plurality of unit cells, including a first unit cell and a second unit cell; and a bonding step of bonding the unit cells via the uncured second bus electrode.

2. The method of claim 1 , further comprising a second curing process for hardening the combined unit cells after the bonding process.

3. The first unit cell includes a first cell electrode formed on a first unit substrate and having conductivity, The second unit cell includes a second cell electrode formed on a second unit substrate and having conductivity, The method of claim 1 , wherein the second cell electrode and the first cell electrode are bonded to each other without a bonding material to combine the second unit cell and the first unit cell.

4. The first cell electrodes include a first lower cell electrode and a first upper cell electrode formed on one surface and the other surface of the first unit substrate, respectively. The second cell electrodes include a second lower cell electrode and a second upper cell electrode formed on one surface and the other surface of the second unit substrate, respectively. The method of claim 3, wherein the second unit cell and the first unit cell are combined by bonding the second lower cell electrode and the first upper cell electrode to each other.

5. The method of claim 4, wherein the first upper cell electrode is formed in an uncured state such that the thickness of the first upper cell electrode is reduced by bonding the second lower cell electrode thereto.

6. 5. The method of claim 4, wherein at least one of the second lower cell electrode and the first upper cell electrode is formed in an uncured state to bond the second unit cell and the first unit cell.

7. the first upper cell electrode is formed to have a first thickness; the second lower cell electrode is formed to have a second thickness; 5. The method of claim 4, wherein a third thickness between the first unit cell and the second unit cell formed by bonding the second lower cell electrode and the first upper cell electrode has a value smaller than a sum of the second thickness and the first thickness.

8. 5. The method of claim 4, wherein the second lower cell electrode and the first upper cell electrode are joined to each other, and the second unit cell and the first unit cell are disposed to partially overlap each other in a first axis direction in which the second unit cell and the first unit cell are spaced apart.

9. 5. The method of claim 4, wherein the second lower cell electrode and the first upper cell electrode are formed to have the same thickness when the second lower cell electrode and the first upper cell electrode are bonded to each other.

10. The method of claim 3 , wherein the first cell electrode and the second cell electrode are both made of the same material and are bonded to each other.

11. the first upper cell electrode includes a first bonding electrode bonded to the second lower cell electrode, The method of claim 4 , wherein the first bonding electrode includes a first bonding surface facing the second lower cell electrode, and an insertion groove formed in the first bonding surface.

12. the first bonding electrode further includes a first bonding finger bar formed so that the insertion groove is disposed inside the first bonding finger bar, 12. The method of claim 11, wherein the first joint finger bar includes a first joint finger member formed along a direction perpendicular to a direction in which the first unit cell and the second unit cell are spaced apart, and a second joint finger member coupled to the first joint finger member.

13. 12. The method of claim 11, wherein the first upper cell electrode includes a first unbonded electrode coupled to the first bonded electrode, the first unbonded electrode including a plurality of first unbonded finger bars spaced apart from each other.

14. the second lower cell electrode includes a second bonding electrode bonded to the first bonding electrode, the second bonding electrode includes a second bonding surface facing the first bonding electrode; The method of claim 11, wherein the second bonding surface is formed in a flat, planar shape before the second bonding electrode and the first bonding electrode are bonded to each other.

15. the second lower cell electrode includes a second bonding electrode coupled to the first bonding electrode; The method of claim 11, wherein the second bonding electrode includes an insertion member bonded to the first bonding electrode and inserted into the insertion groove.

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