Optical structures that increase the efficiency of solar cells

Abstract

1. An optical structure comprising: a first region (106a,b) of a solar cell (102a,b), which is a less active edge region of the solar cell (102a,b), at least partially covered by an overlapping optical layer element (104), the overlapping optical layer structure configured to at least partially redirect light initially directed towards the first region (106a,b), the redirected light being directed towards a second region (108a,b), optionally comprising a central region of the solar cell (102a,b), the second region (108a,b) being a more active region than the first region (106a,b), thereby preferably providing higher energy and improved overall gain in the solar cell (102a,b) or a module including the solar cell (102a,b) due to improved light conversion efficiency. Methods for increasing the efficiency of solar cells (102a, b) or related modules and methods for manufacturing optical structures are also provided.

Description

[Technical Field]

[0001] The present invention relates generally to optical structures, and more particularly to optical structures in which a first region of a solar cell is at least partially covered by an overlapping optical layer element. [Background technology]

[0002] Various PV (photovoltaic) cells have different efficiency curves over the edge region, and various aspects, such as different edge structures with and without conductive layers, conductors, fingers, passivation, etc., affect the inactive cell edge region and the total loss of the entire area due to edge recombination. In particular, n-type silicon cells, such as silicon heterojunction cells (SHJ / HTJ) and TopCon, have poor edge structures and inefficient (less active) edge regions, while still other cell types, such as p-type silicon cells, typically also have at least a small inactive or at least less active edge region.

[0003] There are various factors that contribute to efficiency losses in full-size and cut-size cells. Many strategies have been proposed to improve these losses, including a) overlapping or shingle cell structures, b) better control of the conductive layer on the edges through conductive finger locations, c) edge passivation, d) improved edge cutting, and e) improved cell coating uniformity. All of these do not solve the total losses, and no real industrial solution yet exists, and several challenges still exist that negatively impact yield and cost.

[0004] One typical module (several connected solar cells) structure utilizes an overlapping cell design, in which one cell edge is covered by another. This approach hides one inefficient cell edge, but leaves the other edge visible, so the inefficient edge area still reduces the total energy gain. There is also a shingle structure, in which every other cell is on top of an adjacent cell, but the overlapping cells still have their entire edges visible, so this approach also does not completely solve the problem of inactive edge area. Furthermore, both module structures are more difficult to manufacture with high yields, so many module manufacturers have already decided to discontinue these module structures.

[0005] Another alternative is to use edge passivation treatment for the inactive cell edge regions to minimize edge recombination losses. This has been extensively studied but has not yet been realized in practical manufacturing. New manufacturing methods with good yields need to be developed. A completely satisfactory solution for this purpose does not yet exist.

[0006] Edge recombination can also be minimized by a conductive finger grid on top of the cell that is some distance away from the edge regions, and a horizontal conductive layer such as a transparent conductive oxide (TCO) or other equivalent conductive layer that is controlled at the edge regions so that a uniform layer covers the entire surface or leaves the edge regions uncovered. However, these optimizations are not sufficient to replace edge recombination or eliminate the inactive edge regions. Summary of the Invention

[0007] It is an object of the present invention to alleviate at least some of the problems in the prior art. According to one aspect of the present invention, there is provided an optical structure, wherein a first region of a solar cell, which is a less active edge region of the solar cell, is at least partially covered by an overlapping optical layer element, the overlapping optical layer element configured to at least partially redirect light originally directed towards the first region, and the redirected light is directed towards a second region of the solar cell, optionally including a central region, which is more active than the first region, thereby preferably providing higher energy and improved overall gain in the solar cell or a module including the solar cell due to increased light conversion efficiency.

[0008] Various embodiments of the present invention provide novel optical improvements, for example, in the form of arrangements (structures) and methods for addressing the above-mentioned inactive or less active cell edge regions and the associated efficiency losses. Accordingly, the less active edge regions of a solar or PV cell may be at least partially covered by overlapping optical layer elements, incorporating or essentially being optical layers or optical layer structures, that redirect incident light from the first edge region toward a more active second region of the cell, typically the central region, providing increased light conversion efficiency with more energy and improved overall gain in the associated solar cell or module. This approach is simple to implement, produces power gains on the module, and is easily integrated into a variety of module architectures.

[0009] An overlapping optical layer structure configured to redirect incident light from a first region to a second region can refer to an overlapping optical layer structure that, for example, reflects and / or transmits at least a portion of light originally directed from the environment to a first location on the first region, redirecting the light in another direction, to a second location different from the first location. The redirected light can be reflected from the overlapping optical layer structure toward an additional element, such as a glass element, from which the light can be further reflected and directed toward a second region of the solar cell. Additionally or alternatively, at least a portion of the light originally directed to the first location can be transmitted through the overlapping optical layer structure and, optionally, refracted and directed toward the first or additional location on the solar cell. This can also increase the overall gain or efficiency of the solar cell.

[0010] The proposed structure of the overlapping optical layer elements can improve solar cell module efficiency even in narrow cell gaps, for example, when using HJT, SHJ, and other solar cell types with wide, less efficient edge regions.

[0011] The function of the overlapping optical layer elements may be based on reflection, refraction, transmission, scattering diffraction, or any combination thereof.

[0012] The overlapping optical layer elements may be formed by or include optical patterns such as buried cavity optical elements, optionally including cavities of air or other gas.

[0013] The overlapping optical layer elements may be formed by or include optical patterns, combinations of materials with different refractive indices, and / or reflective coatings.

[0014] The materials of the overlapping optical layer elements may include or be based on transparent polymers, thermoplastic or thermoset resins, glass or ceramic materials, and / or combinations of different layers, potentially including opaque coatings.

[0015] The material of the overlapping optical layer elements may include or be based on an opaque material, optionally including a metal coating.

[0016] The overlapping optical layer element may include a film (e.g., tape or other type of film) between the cell and the string spacing, including the module edge region and the interconnection region, with the film or tape overlapping the cell edge region as described elsewhere herein. The width of the film or tape may be, for example, from about 1 mm to several mm. For example, so-called SEO (Solar Energy Optics) film may be used.

[0017] One preferred overlapping optical layer element includes or is a partially reflective and partially transmissive film, which may be optimized for PV cell edge efficiency characteristics by optimal (as desired / selectively optimized) redirection and transmission capabilities to achieve maximum gain values ​​at each edge region. For example, the density of the optical pattern in the overlapping optical layer element may be configured to gradually or linearly change (increase or decrease), at least locally, to optimize the redirected and transmitted light on the cell surface, for example, depending on the type of PV cell and its edge efficiency profile (increase or decrease from the cell edge). The transmitted light may also be controlled by different optical strategies, which have a positive effect on capturing the maximum amount of light for energy conversion on the surface of the PV cell for different incident angles of light.

[0018] The overlapping optical layer structures (e.g., films or, more particularly, tapes) can be easily integrated into a variety of modular structures. The overlapping optical layer elements can be pre-prepared, e.g., with adhesive. Alternatively, the overlapping optical layer elements can be prepared in situ.

[0019] The overlapping optical layer structure, or at least a film of the overlapping optical layer structure, may be applied to the inside surface of the top glass by an optically clear adhesive (OCA), EVA (ethyl vinyl acetate), optical hot melt, or the like.

[0020] The overlap optical layer structure may also be applied to the cell surface, particularly the cell edge region, overlapping, for example, two different string lines, for example, with EVA or other adhesive. This overlap optical layer structure may be applied over the cell surface, the cell edge region, the string or cell spacing, or between the cell and the interconnect. This provides an additional benefit in addition to the power gain described above: the cell matrix and string line arrangement may be fixed by applying an overlap optical structure containing adhesive, preventing movement of the cell matrix and string lines during the manufacturing process, thereby aiding module fabrication, stacking, and ultimate yield. The use of additional fixation tape is not necessary. Figures herein show a cell-adhesive overlap optical layer structure, tape. Furthermore, the overlap optical layer structure may be applied over the encapsulation layer, which may be EVA, POE, TPO, or the like. The overlap optical layer structure may also be utilized on the back surface of the cells, particularly if the module has, for example, a back glass and a sufficient amount of light is available from that side as well (e.g., a vertically installed module wall), allowing bifacial PV cells to have similar gain benefits as on the front surface of the module.

[0021] The overlapping optical layer structure contemplated herein provides a very attractive approach to improving the power output and efficiency of PV modules. The utility of this approach also lies in introducing an economical alternative to the demanding edge passivation or shingled cell construction associated with PV modules. Furthermore, the present invention allows for the utilization of a cell gap, where the cell edges can be covered by an optical film / tape that includes cell edge overlap, and edge passivation and shingled cell construction are not required.

[0022] The present invention also relates to the use of an overlapping optical layer element, preferably comprising a film that at least partially overlaps a first edge region of a solar cell, to at least partially redirect light that was originally directed toward a first region, wherein the redirected light is directed toward at least a second region, preferably a more active region, such as a central region of the solar cell.

[0023] Also provided is a method for improving the efficiency of a solar cell or related module, said method comprising at least partially covering a first edge region of a solar cell with an overlapping optical layer element configured to redirect light initially directed towards the first region, wherein the redirected light is at least partially directed towards a selected second region of the solar cell, preferably a more active region, optionally including a central region, whereby preferably during operation, higher energy and improved overall gain is provided in said solar cell or a module including said cell due to improved and better light conversion efficiency.

[0024] The present invention also relates to a method for manufacturing an optical structure, the method comprising: providing a string of solar cells; and providing at least one overlapping optical layer element to at least partially cover a first edge region of at least a first solar cell and a first edge region of at least a second adjacent solar cell of the string of solar cells, the overlapping optical layer element being configured to redirect light initially directed toward the first region of each solar cell, such that the redirected light is at least partially directed toward a selected second region of each solar cell, preferably a more active region, optionally including a central region.

[0025] Providing the overlapping optical layer elements can include adhesively attaching the overlapping optical layer elements to surfaces of the first and second solar cells to stabilize the cell matrix and string line positions during fabrication of the structure.

[0026] The exemplary embodiments presented herein should not be construed as limiting the applicability of the appended claims. The verb "comprise" is used in this text as an open limitation that does not exclude the presence of unrecited features. Features recited in dependent claims may be freely combined with each other unless expressly stated otherwise.

[0027] The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. However, the invention itself, both as to its structure and its method of operation, together with further objects and advantages thereof, will best be understood from the following description of specific illustrative embodiments when read in connection with the accompanying drawings. [Brief explanation of the drawings]

[0028] The invention will now be described in more detail with reference to exemplary embodiments according to the accompanying drawings. [Figure 1] 1 illustrates an example of at least a portion of an optical structure. [Figure 2] An example of at least a portion of an optical structure is described. [Figure 3] 1 shows the efficiency of a solar cell as a function of distance from the edge of the solar cell. [Figure 4] 1 shows the solar cell power associated with a module of solar cells, the associated gain, and watt-peak / module. [Figure 5] 1 shows the efficiency of a solar cell as a function of distance from the edge of the solar cell relative to the solar cell module. [Figure 6] 10 shows calculations of module power and additional gain for optical structures provided as modules with different string / cell spacing and with overlapping optical layer elements with different film overlaps. [Figure 7] A comparison is shown between a single structure PV module and a PV module that may be provided in accordance with the present invention as an optical structure with optimized solar cell 102 spacing and associated overlapping optical layer elements 104. DETAILED DESCRIPTION OF THE INVENTION

[0029] Figure 1 shows an example of at least a portion of an optical structure. The optical structure includes at least one solar cell 102. The optical structure further includes at least one overlapping optical layer element 104. Note that Figure 1 shows only a portion of the optical structure, and the structure continues to the right.

[0030] The overlapping optical layer element 104 at least partially covers the solar cell 102. The optical layer element 104 at least partially covers a first region 106 (shown schematically in FIG. 1 ) of the solar cell 102. The first region 106 corresponds to an edge region of the surface of the solar cell 102, where the first region is less active or less efficient than other regions of the solar cell 102. The first region 106 may be less efficient than other regions of the solar cell 102 at converting light to electricity.

[0031] The optical layer element 104 may be in contact with the surface of the solar cell 102, or the optical layer element 104 may be applied to the surface of the solar cell 102, for example by using an adhesive.

[0032] The overlapping optical layer element 104 is configured to redirect at least a portion of light originally directed toward the first region 106, such that the redirected light is at least partially directed toward a second region 108 of the solar cell 102. The second region 108 may be a central region of the solar cell 102. The second region 108 is a region of the solar cell 102 that is more active or efficient (can convert light to energy more efficiently) than the first region 106 of the solar cell 102. The redirection of light to the second region 108 may be performed by the overlapping optical layer element 104, or the overlapping optical layer element 104 may redirect light incident on the first region 106 to another element of the structure and then further redirect the light to the second region 108.

[0033] The overlapping optical layer element 104 may additionally or alternatively redirect at least a portion of light that was originally directed to a first location within the first region 106 to at least a second location on the first region 106.

[0034] Thus, the overlapping optical layer elements 104 may reflect and / or transmit light, as also shown in Figure 1. Preferably, most of the light is reflected and redirected away from the inactive edge regions 106 towards the more efficient cell surface areas. Some of the light can be transmitted to the cell surface (see small arrows through the overlapping optical layer elements (films)), which can also increase the overall gain.

[0035] The function of the overlapping optical layer elements 104 may be based on reflection, refraction, transmission, scattering, diffraction, or any combination of the aforementioned optical functions, which may be achieved by included optical patterns, such as an air cavity (or other gas cavity if not a vacuum cavity) and / or an embedded cavity optical element including a combination of optical materials with different refractive indices or different reflective coatings.

[0036] The material of the overlapping optical layer element 104 may preferably include or be based on a transparent polymer, a thermoplastic or thermosetting resin, a glass or ceramic material, and / or a combination of different layers, and may potentially include an opaque coating or material such as a metallic coating.

[0037] The overlapping optical layer element 104 preferably includes or is a film or tape element, such as an SEO film.

[0038] The optical structure may include the backsheet 110 or be provided on the backsheet 110 .

[0039] The optical structure may further include or be coupled to a top glass 112 .

[0040] The overlapping optical layer elements 104 may be provided, for example, to be applied onto the surface of the solar cell 102 or onto the inside surface of the top glass 112 .

[0041] Figure 2 shows an example of at least a portion of an optical structure. The structure of Figure 2 can continue in both the left and right directions. The optical structure of Figure 2 can be a module including solar cells. Figure 2 shows a portion of an optical structure that can include a string of solar cells including at least a first solar cell 102a and a second solar cell 102b.

[0042] The overlapping optical layer element 104 is then configured to at least partially cover a first edge region 106 a of at least a first solar cell 102 a and a first edge region 106 b of at least a second solar cell 102 b adjacent to the string of solar cells. The overlapping optical layer element 104 is configured to redirect light that was originally directed toward the first region 106 a, 106 b of each of the solar cells 102 a, 102 b. The redirected light is at least partially directed toward at least a second region 108 a of the first solar cell 102 a and a second region 108 b of the second solar cell 102 b.

[0043] The structure can include at least one overlapping optical layer element 104. The overlapping optical layer element 104 covers at least a first region 106a of the first solar cell 102a and a first region 106b of the second solar cell 102b. The second regions 108a, 108b are more active than the first (edge) regions 106a, 106b.

[0044] In connection with any optical structure, the overlapping optical layer element 104 can be configured to overlap the edge region of the associated solar cell 102 a, 102 b, where the overlap or "film overlap" along the surface of the first region 106 of the solar cell 102 a, 102 b corresponds to a distance OL from the edge of the solar cell 102 a, 102 b. The film overlap OL can be selected based on the use case. The film overlap OL can also vary between solar cells 102 a, 102 b in the same optical structure.

[0045] The overlapping optical layer element 104 may be applied to the surfaces of the first solar cell 102 a and the second solar cell 102 b using an adhesive layer 114 .

[0046] The optical structure may include or be provided on a backsheet or rear glass 110 .

[0047] The optical structure may further include or be coupled to a top glass 112 .

[0048] The optical structure may include or be provided with an encapsulant 116 .

[0049] It should be noted that overlapping optical layer elements 104 may also be provided elsewhere in the optical structures disclosed above.

[0050] However, when overlapping optical layer elements 104 are applied to the strings of solar cells so as to at least partially cover the cell or string spacing as well, the position of the cell matrix and string lines during structure fabrication can be stabilized.

[0051] FIG. 3 shows the efficiency of a solar cell 102 as a function of distance from the edge of the solar cell 102. As shown in FIG. 3, experimental data from silicon heterojunction half-cell testing shows a decrease in efficiency toward the edge of the cell ("measured-fitted efficiency"). Utilizing the present invention, the overlapping optical layer elements 104 on the first edge region 106 of the PV cell 102 provide improved gain, as can be seen from the curve "effective efficiency calculated with overlapping optical layer elements," thereby increasing the overall efficiency of the solar cell and module. The upper portion of the curve ("effective efficiency calculated with overlapping optical layer elements") in the figure, which has a flattened slope, illustrates this efficiency improvement.

[0052] 4 shows the efficiency of a solar cell 102 as a function of distance from the edge of the solar cell for a solar cell 102 module containing multiple solar cells 102. The efficiency is shown separately for three solar cells 102, and the average is also shown.

[0053] Optimized module efficiency can be obtained when the PV cell edge efficiency profile is measured, for example, using a shadow masking method on the edge / first region 106. Once the efficiency profile is available, the ideal overlapping optical layer elements 104 pattern and its density or specifically the film overlap distance OL can be calculated.

[0054] 5 shows the solar cell power per module, associated gain, and peak watt gain for solar cell modules including solar cells 102 with different film overlaps D. It can be seen that a selected film overlap OL can result in a selected or optimized gain. For example, a film overlap OL of about 1 mm to 2 mm can be advantageous.

[0055] Final module optimization can continue after film overlap OL optimization. The width of the overlap optical layer elements (e.g., films or specifically tapes) can be considered along with the solar cells 102 and string spacing on the module. FIG. 6 shows, by way of example, calculations of module power and additional gain for optical structures provided as modules with different string / cell spacings and with overlap optical layer elements 104 provided by different film overlap OL. Calculations were performed for a 400 Wp HJT module, as well as a reference module with a 2 mm cell and string gap and a module with a 3 mm cell and string gap, showing improved additional gain in the latter.

[0056] When comparing a single structure PV module with a PV module that may be provided in accordance with the present invention as an optical structure with optimized solar cell 102 spacing and associated overlapping optical layer elements 104, improved gain can be achieved, as shown in FIG. 7.

[0057] In a method for increasing the efficiency of a solar cell 102 or an associated module including a plurality of solar cells 102, the method may include at least partially covering a first edge region 106 of the solar cell with an overlapping optical layer element 104 configured to redirect light initially directed toward the first region, such that the redirected light is at least partially directed toward a selected second region of the solar cell 102, preferably a more active region 108, optionally including a central region, thereby preferably providing higher energy and improved overall gain in the solar cell 102 or a module including said cells 102 during operation due to improved and better light conversion efficiency.

[0058] A method for manufacturing an optical structure may include providing a string of solar cells including at least a first solar cell 102 a and a second solar cell 102 b. The method further includes providing at least one overlapping optical layer element 104 to at least partially cover a first edge region 106 a of at least the first solar cell 102 a and a first edge region 106 b of at least a second adjacent solar cell 106 b of the string of solar cells. The overlapping optical layer element 104 is configured to redirect light originally directed toward the first region 106 a, 106 b of each of the solar cells 102 a, 102 b, so that the redirected light is at least partially directed toward a selected second region, preferably a more active region 106 a, 106 b, optionally including a central region, of each solar cell 102 a, 102 b.

[0059] Providing at least one overlapping optical layer element 104 may include adhesively attaching the overlapping optical layer element 104 to the surfaces of the first and second solar cells 102a, 102b to stabilize the cell matrix and string line positions during fabrication of the structure.

[0060] Considering a module having a string of solar cells 102a, 102b, at least some of the solar cells 102a, 102b may have an associated overlapping optical layer element 104. Also, all cells 102a, 102b of the string of solar cells may have at least one (or more) associated overlapping optical layer element 104.

[0061] The present invention and related overlap optical layer elements 104, provided as films / tapes with selected film overlap OL, can provide additional power gain and stabilize the power and quality of modules or optical structures by reducing the cost of module / structure manufacturing, particularly by replacing the need for edge passivation, replacing the most advanced cell cutting techniques, and stabilizing the cell matrix and string line position. This can stabilize the gain in edge regions, which can vary or shift during outdoor use (see: damp heat reduces gain at the edges of cells). The overlap optical layer elements 104 are stable under outdoor use and do not cause gain loss. The overlap optical layer elements 104 can cover inefficient and unstable edge regions of PV cells 102, stabilizing module function. The overlap optical layer elements 104 are suitable for covering any type of inefficient and unstable areas and spacing to provide improved power gain associated with the module.

[0062] The present invention has been described above with reference to the above-mentioned embodiments, and some advantages of the present invention have been demonstrated. It is clear that the present invention is not limited to these embodiments, but encompasses all possible embodiments within the spirit and scope of the inventive idea and the scope of the following claims.

[0063] The features recited in the dependent claims may be freely combined with one another unless expressly stated otherwise.

Claims

1. An optical structure comprising: a first region of the solar cell, the first region being a less active edge region of the solar cell, at least partially covered by an overlapping optical layer element; the overlapping optical layer structure is configured to at least partially redirect light that was originally directed toward the first region; the redirected light is directed toward a second region of the solar cell, optionally including a central region; the second region is a region having a higher activity than the first region, This preferably provides an optical structure with increased light conversion efficiency, thereby providing higher energy and improved overall gain in the solar cell or in a module including the solar cell.

2. 10. The structure of claim 1, wherein the function of the overlapping optical layer elements is based on reflection, refraction, transmission, scattering diffraction, or any combination thereof.

3. 3. A structure according to claim 1 or 2, wherein the overlapping optical layer elements are formed by or include optical patterns such as buried cavity optical elements, optionally including cavities of air or other gas.

4. The structure of any one of claims 1 to 3, wherein the overlapping optical layer elements are formed by or include optical patterns, combinations of materials with different refractive indices, and / or reflective coatings.

5. 5. A structure according to any one of claims 1 to 4, wherein the material of the overlapping optical layer elements preferably comprises or is based on transparent polymers, thermoplastic or thermosetting resins, glass or ceramic materials, and / or combinations of different layers, potentially including opaque coatings.

6. A structure according to any one of claims 1 to 5, wherein the material of the overlapping optical layer elements comprises or is based on an opaque material, optionally including a metal coating.

7. 7. The structure of any one of claims 1 to 6, wherein the overlapping optical layer elements comprise a film, or specifically a tape, between the solar cells and string spacing including module edge regions and interconnection regions, the film or tape overlapping the cell edge regions.

8. the overlapping optical layer elements include or are partially reflective and partially transmissive films; 8. A structure according to any one of claims 1 to 7, wherein the film may be optimised for PV cell edge efficiency characteristics by optimum (as desired / selectively optimised) combination of turning and transmission to achieve maximum gain values ​​at each edge region.

9. The structure of any one of claims 1 to 8, wherein the optical pattern density in the overlapping optical layer elements is configured to increase or decrease, at least locally, gradually or linearly.

10. 1. Use of an overlapping optical layer element (preferably comprising a film) at least partially overlapping a first edge region of a solar cell to at least partially redirect light initially directed toward the first region, comprising: The redirected light is directed towards at least a second region, preferably a more active region, such as a central region of a solar cell.

11. 1. A method for improving the efficiency of a solar cell or associated module, comprising at least partially covering a first edge region of the solar cell with an overlapping optical layer element configured to redirect light initially directed toward the first region, the redirected light is at least partially directed to a selected second region of the solar cell, preferably a more active region, optionally including a central region; This preferably results in a method whereby during operation, higher energy and improved overall gain is provided in the solar cell or module containing the cell due to improved and better light conversion efficiency.

12. providing a string of solar cells; providing at least one overlapping optical layer element to at least partially cover a first edge region of at least a first solar cell and a first edge region of an adjacent at least a second solar cell of a string of solar cells; the overlapping optical layer elements are configured to redirect light that is initially directed toward the first region of each solar cell; The method wherein the redirected light is at least partially directed to a selected second region of each solar cell, preferably a more active region, optionally including a central region.

13. 13. The method of claim 12, wherein providing the overlapping optical layer elements comprises adhesively attaching the overlapping optical layer elements to surfaces of the first solar cell and the second solar cell to stabilize cell matrix and string line positions during fabrication of the structure.

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