Solar cell, electrode structure thereof and photovoltaic module

Abstract

The invention provides a solar cell, an electrode structure thereof and a photovoltaic module, and relates to the field of photovoltaic technology. The electrode structure comprises a main grid line and a transition section group, the main grid line is located at a position corresponding to a test probe row, the transition section group comprises a plurality of transition sections used for being in lap joint with fine grid lines, and the height of the main grid line is larger than that of the transition section in the first transition section group connected with the main grid line. The height of the main grid line at the corresponding position of the test probe row is greater than the height of the transition section connected with the main grid line, the contact density of the test probe row and the main grid line is increased, the resistance Rs is reduced, the efficiency loss caused by test defects is reduced, and the test precision is improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell and its electrode structure, and a photovoltaic module. Background Art

[0002] In recent years, the development and utilization of renewable energy has received increasing attention. Solar energy, due to its cleanliness, safety, high energy content, and widespread distribution, has gradually become a major form of energy supply. Solar cells are semiconductor components that can effectively absorb solar energy and convert it into electricity.

[0003] Metallization is a key process in solar cells, primarily used to create the electrodes. Solar cell electrodes typically consist of busbars (BBs) and finger lines (also known as fins). The busbars primarily serve to collect current from the finger lines and connect them in series, while the finger lines collect photogenerated carriers. The connection between the busbars and finger lines enables current collection and transmission.

[0004] The grid lines of solar cells are typically made using screen-printed conductive silver paste. The large amount of silver paste used increases the cost of solar cells. Furthermore, the grid lines may create some optical obstruction on the cell surface, reducing photon generation and, consequently, the cell's current, impacting efficiency. Consequently, busbarless (OBB) solar cells have gained widespread adoption due to their low cost and other advantages. To verify that a solar cell meets requirements, a test device can be used to measure its efficiency. Summary of the Invention

[0005] In order to alleviate, mitigate or eliminate the above-mentioned technical problems, the present application provides a solar cell and its electrode structure, and a photovoltaic module, which can improve the accuracy of testing.

[0006] In a first aspect, the present application provides an electrode structure for a solar cell, comprising:

[0007] Fine grid lines are arranged at intervals along a first direction and extend along a second direction, the fine grid lines having a probe row area and a non-probe row area, the probe row area corresponding to a position of a test probe row when the solar cell is tested;

[0008] Main grid lines are arranged at intervals along the second direction and extend along the first direction, and the main grid lines are located in the probe row area;

[0009] a gradient segment group arranged at intervals along the second direction, the gradient segment group comprising a plurality of gradient segments extending along the second direction and arranged at intervals along the first direction, the gradient segments being configured to overlap with the fine grid lines;

[0010] The gradient segment group includes a first gradient segment group connected to the main grid line, and the height of the main grid line is greater than the height of the gradient segments in the first gradient segment group.

[0011] In a possible implementation, the height of the main grid line is 1-2 μm greater than the height of the gradient segments in the first gradient segment group.

[0012] In a possible implementation, the height of the main grid line is 3-9 μm.

[0013] In a possible implementation, the height of the gradient section is 2-8 μm.

[0014] In a possible implementation, the height of the gradient section gradually increases from both ends to the middle.

[0015] In a possible implementation, the main grid lines are symmetrically and evenly distributed in the second direction.

[0016] In a possible implementation, the gradient segment group further includes a second gradient segment group, and one or more second gradient segment groups are spaced between some adjacent two main grid lines.

[0017] A possible implementation also includes:

[0018] A harpoon structure is located at both ends of the gradient segment group, the harpoon structure includes two bifurcated lines, one end of the two bifurcated lines intersects at a connection point, and the distance between the other end points is 1.5-2.5 mm;

[0019] The harpoon structures at both ends of the position where the first gradient segment group is located are connected to the main grid line at the connection point.

[0020] In a second aspect, the present application provides a solar cell, comprising:

[0021] A semiconductor substrate having a front surface and a back surface in a thickness direction thereof, wherein the front surface and / or the back surface is provided with the electrode structure described in the first aspect.

[0022] In a third aspect, the present application provides a photovoltaic assembly comprising the solar cell according to the second aspect, wherein a plurality of the solar cells are electrically connected into a cell string.

[0023] Compared with the prior art, this application has the following advantages:

[0024] The electrode structure provided by the present application includes a main grid line and a gradient segment group. The main grid line is located at a position corresponding to a test probe row. The gradient segment group includes multiple gradient segments for overlapping with fine grid lines. The height of the main grid line is greater than the height of the gradient segments in the first gradient segment group connected to the main grid line. The present application makes the height of the main grid line at the corresponding position of the test probe row greater than the height of the gradient segment connected to it, increases the contact density between the test probe row and the main grid line, reduces the resistance Rs, reduces the efficiency loss caused by test defects, and improves test accuracy.

[0025] The solar cell and photovoltaic module provided in this application include the above-mentioned electrode structure and thus have the same effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the present application. They are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the accompanying drawings:

[0027] Figure 1 is a partial cross-sectional schematic diagram of a solar cell provided in an embodiment of the present application;

[0028] Figure 2 is a schematic diagram of an electrode structure provided in an embodiment of the present application;

[0029] Figure 3 is a partial cross-sectional schematic diagram of an electrode structure provided in an embodiment of the present application;

[0030] Figure 4 It is a partial cross-sectional schematic diagram of another electrode structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0032] As used herein, unless the context clearly indicates otherwise, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the elements specifically identified, and these elements do not constitute an exclusive list; the device may also include other elements.

[0033] Unless otherwise specifically stated, the relative arrangement of the parts, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0034] In the description of this application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of this application.

[0035] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0036] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terms used in this application are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application should be understood not only by the actual terms used, but also by the meaning implied by each term.

[0037] It should be understood that when a component is referred to as being “on,” “connected to,” “coupled to,” or “contacting” another component, it can be directly on, connected to, coupled to, or contacting the other component, or intervening components may be present. In contrast, when a component is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly contacting” another component, there are no intervening components present.

[0038] Figure 1 FIG is a partial cross-sectional schematic diagram of a solar cell provided in an embodiment of the present application. Figure 1 As shown, the solar cell 100 includes a semiconductor substrate 101 having a front side and a back side in its thickness direction. When the solar cell 100 is in operation, the front side faces the sun. A plurality of solar cells 100 can be electrically connected into a cell string to form a photovoltaic module.

[0039] Electrode structures are formed on the front and / or back sides of the solar cell 100 to conduct the current generated by the solar cell 100. Electrode structures may be provided on both the front and back sides of the solar cell 100, and the electrode structures on the front and back sides may be the same or different. Alternatively, the electrode structure may be provided only on the back side of the solar cell 100.

[0040] In some embodiments, please refer to Figure 1 The front side of the semiconductor substrate 101 includes, from the inside out, a front tunneling oxide layer 1011, a front polysilicon layer 1012, a front passivation layer 1013, and a front electrode 1014. The front electrode 1014 passes through the front passivation layer 1013 and contacts the front polysilicon layer 1012. The back side of the semiconductor substrate 101 includes, from the inside out, a back tunneling oxide layer 1021, a back polysilicon layer 1022, a back passivation layer 1023, and a back electrode 1024. The back electrode 1024 passes through the back passivation layer 1023 and contacts the back polysilicon layer 1022.

[0041] Figure 2This is a schematic diagram of an electrode structure provided in an embodiment of the present application. Figure 2 As shown, the electrode structure 200 includes a main grid line 201, a fine grid line 202, and a gradient segment group 203. The main grid line 201 extends along a first direction A and is arranged at intervals along a second direction B. The fine grid line 202 extends along the second direction B and is arranged at intervals along the first direction A. The gradient segment group 203 is arranged at intervals along the second direction B. The gradient segment group 203 includes a plurality of gradient segments 230 extending along the second direction B and arranged at intervals along the first direction A.

[0042] In some embodiments, the length of the gradient section 230 (the length in the second direction B) is 0.5-1.5 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.3 mm, or 1.5 mm. The width of the gradient section 230 (the length in the first direction A) is 0.03-0.1 mm, for example, 0.03 mm, 0.05 mm, 0.08 mm, or 0.1 mm. This reduces the shading area while also lowering the risk of fusing the fine grid lines during welding.

[0043] For example, when preparing an electrode structure on the surface of a solar cell, the main grid lines 201 are first printed on the surface (front and / or back) of the solar cell, and the gradient segments 230 are printed at the intersections of the main grid lines 201 and the fine grid lines 202 to be printed later, and then the fine grid lines 202 are printed. By overlapping the fine grid lines 202 with these gradient segments 230, it is possible to prevent grid breakage when the fine grid lines 202 are subsequently printed, and to avoid the fine grid lines 202 from being melted due to excessive temperatures during the pressure welding process.

[0044] The fine grid line 202 has a probe row area 2021 and a non-probe row area 2022, wherein the probe row area 2021 corresponds to the position of the test probe row when the solar cell is tested. The main grid line 201 is located in the probe row area 2021. When testing the efficiency of the solar cell, the test probe row can be brought into contact with the main grid line 201. The gradient segment group 203 includes a first gradient segment group 2031 connected to the main grid line 201 located in the probe row area 2021. The height of the main grid line 201 located in the probe row area 2021 is greater than the height of the gradient segment 230 in the first gradient segment group 2031, as shown in FIG. Figure 3 and Figure 4 Compared with a solution having busbars and gradient segments of the same height, this embodiment can increase the contact density between the test probe rows and the busbars 201, reduce the resistance Rs, reduce the efficiency loss caused by test defects, and improve test accuracy.

[0045] For example, after the test probe row position of the IV (power supply-voltage) test machine and the metallization graphic design, the screen film thickness of the main grid line position tested by the test probe row in the graphic design is increased during screen making, so that the main grid line height h1 at this location is greater than the gradient section height h2, thereby increasing the contact density between the test probe row and the main grid, reducing Rs, reducing efficiency loss caused by test defects, and improving test accuracy.

[0046] In some embodiments, the main grid line height h1 is 1-2 μm greater than the gradient segment height h2. For example, h1 is approximately 3-9 μm, h2 is approximately 2-8 μm, and the difference between h1 and h2 is approximately 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, or 2 μm. For example, h1 is 3 μm and h2 is 2 μm; or h1 is 6 μm and h2 is 3 μm; or h1 is 8 μm and h2 is 6 μm; or h1 is 9 μm and h2 is 8 μm. This ensures sufficient contact density between the test probe row and the main grid line, while preventing the main grid line from being too high, which may cause the fine grid line to break at this location.

[0047] Please refer to Figure 4 The height of the gradient section 230 can be gradually increased from both ends to the middle to further prevent the fine grid lines from being broken. In this case, h2 refers to the height of the junction between the gradient section 230 and the main grid line 201.

[0048] Continue to refer Figure 2 , the main grid lines can be removed from the non-probe row area 2022, and the gradient segment group is retained. The gradient segment group in the non-probe row area 2022 is called the second gradient segment group, that is, one or more second gradient segment groups are spaced between two adjacent main grid lines. This can reduce the metal (such as silver) consumption of the main grid lines and reduce the shading of the main grid lines. There is no need to modify the test machine and the test probe row. Only the main grid line graphic design of the screen needs to be changed to make the solar cell meet the test requirements. It should be understood that the height of the gradient segment in the second gradient segment group can be the same as the height of the gradient segment in the first gradient segment group, or it can be different, as long as it can meet the welding requirements.

[0049] It should be noted that the busbars may be provided only in the probe row area 2021, while the busbars may not be provided in the non-probe row area 2022. Figure 2 As shown, the metal consumption of the busbar is reduced, and the light shielding of the busbar is reduced. In some other embodiments, the busbars can be set in both the probe row area 2021 and the non-probe row area 2022.

[0050] In some embodiments, the busbars 201 are symmetrically and evenly distributed in the second direction B to ensure uniform current collection. For example, for a 9BB solar cell, if the test probes are arranged in 6 rows, the 1st, 2nd, 4th, 6th, 8th, and 9th busbars can be retained. Figure 2For another example, for a 14BB solar cell, if there are 10 test probe rows, the 1st, 2nd, 4th, 5th, 7th, 8th, 10th, 11th, 13th, and 14th busbars, or the 1st, 3rd, 4th, 6th, 7th, 8th, 9th, 11th, 12th, and 14th busbars can be retained.

[0051] In some embodiments, harpoon structures 204 are further provided at both ends of the transition segment group 203. The harpoon structures 204 at both ends of the first transition segment group 2031 connect to the busbar 201 at connection points 2043 to facilitate current transmission. No fine grid lines are printed in the middle of the harpoon structures 204, minimizing height differences during string soldering and reducing potential battery cracking or fragmentation caused by string soldering.

[0052] The harpoon structure 204 includes a first bifurcation line 2041 and a second bifurcation line 2042. One end of the first bifurcation line 2041 and the second bifurcation line 2042 intersect at a connection point 2043, and the distance between the other end points is 1.5-2.5 mm, such as 1.5 mm, 1.8 mm, 2.3 mm or 2.5 mm, which avoids the risk of squeezing the battery to cause hidden cracks or fragments while improving the current collection efficiency.

[0053] The basic concepts have been described above. It will be apparent to those skilled in the art that the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to this application. Such modifications, improvements, and amendments are suggested in this application and remain within the spirit and scope of the exemplary embodiments of this application.

[0054] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0055] Similarly, it should be noted that, in order to simplify the description of the present disclosure and thus facilitate understanding of one or more embodiments, the foregoing descriptions of the embodiments of the present disclosure sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of the present disclosure requires more features than those mentioned. In fact, the features of an embodiment may be fewer than all the features of the individual embodiments disclosed above.

[0056] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0057] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present application, they will fall within the scope of the present application.

Claims

1. An electrode structure of a solar cell, characterized in that: include: Fine grid lines are arranged at intervals along a first direction and extend along a second direction, the fine grid lines having a probe row area and a non-probe row area, the probe row area corresponding to a position of a test probe row when the solar cell is tested; Main grid lines are arranged at intervals along the second direction and extend along the first direction, and the main grid lines are located in the probe row area; a gradient segment group arranged at intervals along the second direction, the gradient segment group comprising a plurality of gradient segments extending along the second direction and arranged at intervals along the first direction, the gradient segments being used to overlap with the fine grid lines; The gradient segment group includes a first gradient segment group connected to the main grid line, and the height of the main grid line is greater than the height of the gradient segments in the first gradient segment group.

2. The electrode structure according to claim 1, characterized in that: The height of the main grid line is 1-2 μm greater than the height of the gradient segments in the first gradient segment group.

3. The electrode structure according to claim 1 or 2, characterized in that: The height of the main grid line is 3-9 μm.

4. The electrode structure according to claim 1 or 2, characterized in that: The height of the gradient section is 2-8 μm.

5. The electrode structure according to claim 1 or 2, characterized in that: The height of the gradient section gradually increases from both ends to the middle.

6. The electrode structure according to claim 1, characterized in that: The main grid lines are symmetrically and evenly distributed in the second direction.

7. The electrode structure according to claim 1 or 6, characterized in that: The gradient segment group further includes a second gradient segment group, and one or more second gradient segment groups are spaced between some adjacent two main grid lines.

8. The electrode structure according to claim 7, characterized in that: Also includes: A harpoon structure is located at both ends of the gradient segment group, the harpoon structure includes two bifurcated lines, one end of the two bifurcated lines intersects at a connection point, and the distance between the other end points is 1.5-2.5 mm; The harpoon structures at both ends of the position where the first gradient segment group is located are connected to the main grid line at the connection point.

9. A solar cell, characterized in that: include: A semiconductor substrate, wherein the semiconductor substrate has a front side and a back side in a thickness direction thereof, wherein the front side and / or the back side is provided with the electrode structure according to any one of claims 1 to 8.

10. A photovoltaic module, characterized in that: The solar cell according to claim 9 is comprised of a plurality of solar cells electrically connected into a cell string.

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