Reflective structure, photovoltaic module and method for manufacturing the same
By introducing reflective structures and buffer films into photovoltaic modules, the problem of light energy loss at string gaps is solved, thereby improving photoelectric conversion efficiency and protecting the cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG JINKO SOLAR CO LTD
- Filing Date
- 2021-03-04
- Publication Date
- 2026-07-31
AI Technical Summary
In existing photovoltaic modules, light energy is severely lost at the gaps between strings, resulting in the inability to maximize photoelectric conversion efficiency.
The reflective structure consists of reflective strips and a buffer film. The reflective strips reflect light from the gaps between the strings and the edges of the photovoltaic module onto the cells, while the buffer film alleviates stress concentration at the cell overlaps.
It improved the photoelectric conversion efficiency of photovoltaic modules, increased the overall power by about 2%, and reduced the probability of microcracks in the cells.
Smart Images
Figure CN115985990B_ABST
Abstract
Description
[0001] This application is a divisional application. The original application has the application number 202110241882.0 and the original application date is March 4, 2021. The entire contents of the original application are incorporated herein by reference. Technical Field
[0002] This application relates to the field of photovoltaic module manufacturing technology, and in particular to a reflective structure, a photovoltaic module and a method for its preparation. Background Technology
[0003] With the rapid development of the photovoltaic industry, high-power photovoltaic modules are a key industry goal. However, the presence of gaps between cells and between strings in photovoltaic modules leads to insufficient utilization of light energy. To reduce light energy loss at these gaps, gap-free photovoltaic modules are currently being developed. However, the light energy loss at the string gaps remains unresolved, preventing the maximization of photoelectric conversion efficiency. Summary of the Invention
[0004] The purpose of this application is to provide a reflective structure, a photovoltaic module, and a method for manufacturing the same, so as to solve the problem of light energy loss at the string gaps in the prior art.
[0005] A first aspect of this application provides a reflective structure comprising at least one reflective strip extending along the length of a battery string, the reflective strip being used to reflect light located at the gap between the strings within the photovoltaic module and / or light at the edge of the photovoltaic module onto the battery cells.
[0006] In one possible design, the reflective structure consists of two or more reflective strips, which are parallel to each other and are spaced equidistantly from each other.
[0007] In one possible design, the reflective strip includes a film body and at least one buffer film, the buffer film being fixedly disposed on the film body, the buffer film including an inclined surface, the inclined surface corresponding to the overlapping surface of two adjacent battery cells, and the inclined surface being parallel to the overlapping surface.
[0008] In one possible design, the side of the buffer film facing away from the inclined plane is fixedly attached to the side of the film body near the battery cell.
[0009] In one possible design, the side of the membrane body away from the battery cell is attached to the inclined surface and the buffer membrane on both sides of the membrane body along its length.
[0010] In one possible design, a strip-shaped protrusion is provided on the side of the film body near the battery cell, and the strip-shaped protrusion includes a first reflective surface and a second reflective surface on both sides of the width direction of the film body.
[0011] In one possible design, the film body is disposed at the edge of the photovoltaic module, the length of the first reflective surface is greater than the length of the second reflective surface, and the first reflective surface faces the side where the solar cell is located.
[0012] In one possible design, the maximum thickness of the buffer membrane ranges from 160 to 210 μm, the length of the inclined surface ranges from 150 to 210 mm, and the angle of inclination of the inclined surface ranges from 0.09° to 0.16°.
[0013] In one possible design, the film body comprises, from bottom to top, an adhesive film layer, a substrate layer, and a functional layer, wherein the adhesive film layer is used to fix and attach to the backsheet of the photovoltaic module.
[0014] In one possible design, the functional layer comprises a metal layer or an inorganic material layer.
[0015] In one possible design, the inorganic material layer is a titanium dioxide layer or a glaze layer.
[0016] The second aspect of this application provides a photovoltaic module, which includes the reflective structure provided in the first aspect of this application. The photovoltaic module includes, from bottom to top, a back sheet, the reflective structure, a back encapsulation film, a battery string, a front encapsulation film, and a cover plate. The reflective structure is aligned with the string gap between two adjacent battery strings.
[0017] In one possible design, the battery string includes multiple half-cells, each half-cell including cut portions and connecting portions formed on both sides of the half-cell, wherein the connecting portion of one half-cell overlaps and is fixed to the cut portion of another half-cell.
[0018] In one possible design, the connecting portion is chamfered, and the reflective structure has multiple flanges on both sides in the width direction, with the flanges aligned with the chamfer.
[0019] In one possible design, the distance between two adjacent flanges is 78–82 mm, or 103–107 mm.
[0020] In one possible design, the flange protrudes 3 to 5 mm in the width direction of the reflective structure.
[0021] In one possible design, the photovoltaic module further includes a busbar, with the reflective structure aligned with the position of the busbar.
[0022] In one possible design, the film body has a first strip-shaped protrusion and a second strip-shaped protrusion on the side near the battery cell. The first strip-shaped protrusion has a first reflective part, and the second strip-shaped protrusion has a second reflective part. The first reflective part and the second reflective part are respectively inclined to both sides of the busbar in the width direction, so as to reflect the light illuminating the location of the busbar to the battery cells on both sides of the busbar.
[0023] In one possible design, the centerline of the reflective structure in the length direction is aligned with the centerline of the string gap in the length direction.
[0024] In one possible design, the width of the reflective strip is 2 to 5 times the width of the gap between the battery cells.
[0025] In one possible design, the half-cell is a bifacial solar cell.
[0026] A third aspect of this application also provides a method for preparing a photovoltaic module, wherein the method for preparing the photovoltaic module provided in the second aspect of this application includes the following steps:
[0027] The reflective strip in the reflective structure is glued to a designated position on the back plate facing one side of the battery string;
[0028] The photovoltaic module is formed by sequentially stacking the back sheet with the reflective strips adhered to it, the back sealing film, the battery string, the front sealing film, and the cover plate, and then processing them through subsequent steps.
[0029] In one possible design, attaching the reflective strip in the reflective structure to a predetermined position on the back panel facing one side of the battery string specifically includes:
[0030] The buffer film is bonded to the film body to form the reflective structure;
[0031] The film body is bonded to a designated position on the back plate facing one side of the battery string.
[0032] In one possible design, before sequentially stacking the backsheet with the reflective structure adhered to it, the back sealing film, the battery string, the front sealing film, and the cover plate, and fabricating the photovoltaic module through subsequent processes, the method further includes:
[0033] The entire battery cell is cut to obtain half battery cells;
[0034] A flattening process is used to flatten the round wire welding strip in the radial direction to reduce the radial thickness of the round wire welding strip;
[0035] Two or more of the aforementioned half-cells are welded together using the circular wire welding strip to form the battery string.
[0036] In one possible design, after cutting the entire solar cell to obtain half-cells, the method further includes:
[0037] A buffer layer is provided at the edge of the overlapping area of the half-cell.
[0038] In one possible design, the provision of a buffer layer at the overlap area of the half-cell battery cell specifically includes:
[0039] Apply gel to the overlapping area of the half-cell battery.
[0040] The half-cell battery is left to stand to allow the gel to solidify.
[0041] In one possible design, the half-cell battery is left to stand for 2 to 4 hours.
[0042] In one possible design, the provision of a buffer layer at the overlap area of the half-cell battery cell specifically includes:
[0043] Solid film is used to adhere to the overlapping area of the half-cell battery.
[0044] In one possible design, the thickness of the buffer layer is 1 to 100 μm.
[0045] In one possible design, the width of the buffer layer is 0.2 to 2 mm.
[0046] In one possible design, the flattening process is used to radially flatten the round wire strip to reduce its radial thickness, specifically including:
[0047] A flattening process is used to flatten the portion of the round wire welding strip corresponding to the overlapping area in the radial direction, thereby reducing the radial thickness of the portion of the round wire welding strip corresponding to the overlapping area.
[0048] In one possible design, the flattening process is used to radially flatten the round wire strip to reduce its radial thickness, specifically including:
[0049] A flattening process is used to flatten the portion of the round wire welding strip corresponding to the overlapping area in the radial direction, so that the radial thickness of the portion of the round wire welding strip corresponding to the overlapping area is reduced to 1 / 3 to 1 / 2 of the diameter of the round wire welding strip.
[0050] In one possible design, after flattening the round wire strip radially using a flattening process to reduce the radial thickness of the round wire strip, the method further includes:
[0051] The round wire welding strip is heated according to the annealing temperature of the round wire welding strip material;
[0052] The heated round wire welding strip is then cooled down.
[0053] In one possible design, the cooling process for the heated round wire welding strip specifically includes:
[0054] The round wire welding strip is cooled using either air cooling or water cooling methods.
[0055] In one possible design, bonding the film body to a predetermined position on the backplate facing one side of the battery string specifically includes:
[0056] The film body is heated by a hot air blowing process to pre-melt the film body.
[0057] The pre-molded film body is bonded to a designated position on the back plate and then cured.
[0058] The technical solution provided in this application can achieve the following beneficial effects:
[0059] The reflective structure, photovoltaic module, and fabrication method provided in this application maximize the photoelectric conversion efficiency of the photovoltaic module by fully utilizing the light illuminating the gaps between the strings through the reflective structure. Furthermore, the reflective structure can also be positioned at the edge of the photovoltaic module to reflect light illuminating the outer edge of the module back onto the cells, further improving the photoelectric conversion efficiency. The photovoltaic module with the reflective structure provided in this application can achieve an overall power increase and an increase in power generation of approximately 2%.
[0060] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description
[0061] Figure 1 A top view (I) of a photovoltaic module provided in an embodiment of this application.
[0062] Figure 2 A photovoltaic module provided in one embodiment of this application is in Figure 1 Sectional view at point AA;
[0063] Figure 3 A photovoltaic module provided in another embodiment of this application is Figure 1 Sectional view at point AA;
[0064] Figure 4 This is a magnified view of a portion of the reflective structure;
[0065] Figure 5 This is a schematic diagram of the buffer membrane structure;
[0066] Figure 6 This is a cross-sectional view of the reflective structure;
[0067] Figure 7 for Figure 1 Sectional view at BB;
[0068] Figure 8 A top view (II) of a photovoltaic module provided for an embodiment of this application;
[0069] Figure 9 for Figure 8 Sectional view at CC;
[0070] Figure 10 This is a diagram showing one arrangement of half a solar cell.
[0071] Figure 11 A schematic diagram of a reflective structure;
[0072] Figure 12 This is a diagram showing another arrangement of half a solar cell;
[0073] Figure 13 This is a schematic diagram of another reflective structure;
[0074] Figure 14 A flowchart of a photovoltaic module fabrication method provided in the embodiments of this application;
[0075] Figure 15 This is a diagram showing the state of the round wire welding strip before it is flattened.
[0076] Figure 16 This is a diagram showing the state of the round wire welding strip after it has been flattened.
[0077] Figure 17 This is a diagram showing the flattened state of the portion of the round wire welding strip corresponding to the overlapping area;
[0078] Figure 18 This is a schematic diagram of the structure of a half-cell battery cell combined with a buffer layer.
[0079] Figure label:
[0080] 1-Half a cell;
[0081] 11- Overlapping area;
[0082] 12-Chamfer;
[0083] 13-Buffer layer;
[0084] 14-series gap;
[0085] 2-Round wire welding strip;
[0086] 3-Cover plate;
[0087] 4- Front sealing film;
[0088] 5- Backside sealing film;
[0089] 6-Back panel;
[0090] 7-Reflective strips;
[0091] 71-The film layer itself;
[0092] 711 - Functional Layer;
[0093] 712-substrate layer;
[0094] 713 - Adhesive film layer;
[0095] 714 - Strip-shaped protrusions;
[0096] 7141 - First reflective surface;
[0097] 7142 - Second reflective surface;
[0098] 715 - First strip-shaped protrusion;
[0099] 7151 - First reflective section;
[0100] 716 - Second strip-shaped protrusion;
[0101] 7161 - Second reflector;
[0102] 72-Buffer membrane;
[0103] 73 - Flange portion;
[0104] 8-Busbar;
[0105] a - the length of the inclined plane;
[0106] b - Maximum thickness;
[0107] θ - Angle.
[0108] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation
[0109] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0110] In the description of this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0111] In the description of this specification, it should be understood that the directional terms such as "upper" and "lower" used in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should also be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.
[0112] like Figures 1 to 13 As shown, this application embodiment provides a reflective structure consisting of at least one reflective strip 7 extending along the length of the cell string. The reflective strip 7 is used to reflect light located at the string gap 14 within the photovoltaic module and / or light at the edge of the photovoltaic module onto the cell. The photovoltaic module with the reflective structure provided by this application can achieve an overall power increase and an increase in power generation of approximately 2%.
[0113] The reflective structure corresponds to the position of the string gap 14. When light shines on this reflective structure, it reflects the light onto the solar cells on both sides, ensuring that the light shining on the string gap 14 is fully utilized, thereby maximizing the photoelectric conversion efficiency of the photovoltaic module. Furthermore, the reflective structure can also be placed at the edge of the photovoltaic module to reflect light shining outside the edge of the module back onto the solar cells, further improving the photoelectric conversion efficiency.
[0114] When a photovoltaic module includes only two cell strings, the reflective structure can correspond to the string gap 14 between the two cell strings to reflect light incident on the string gap 14 back onto the two cell strings. Of course, a photovoltaic module can also include multiple cell strings, giving it more than two string gaps 14. In this case, one reflective structure can correspond to one string gap 14, thus avoiding light loss at any string gap 14.
[0115] Among them, the reflective strip 7 is a long strip structure, and the length of the reflective strip 7 can be greater than or equal to the length of the string gap 14, so as to ensure that the light irradiated to the string gap 14 can be fully reflected by the reflective strip 7, thereby improving the photoelectric conversion efficiency of the photovoltaic module.
[0116] In this embodiment, as Figure 1 As shown, the reflective structure consists of two or more reflective strips 7, each of which is parallel to the others and there is an equal distance between adjacent reflective strips 7.
[0117] Between two adjacent reflective strips 7 is a battery string. Light can directly illuminate each battery cell for photoelectric conversion without the need for reflection by the reflective strips 7. Therefore, the reflective strips 7 only need to be set at a position aligned with the string gap 14 to reflect the light illuminating the string gap 14 onto the battery cell, thereby achieving full utilization of light energy.
[0118] As a specific implementation, the reflective strip 7 includes a film body 71 and at least one buffer film 72. The buffer film 72 is fixedly disposed on the film body 71. The buffer film 72 includes an inclined surface, which is aligned with the overlapping surface of two adjacent battery cells and is parallel to the overlapping surface.
[0119] It should be noted that the battery string is composed of multiple battery cells stacked sequentially, meaning the edge of one battery cell overlaps the edge of another. The overlapping area of two battery cells forms an overlap region 11, and the surface of the overlap region 11 forms an overlap surface. The battery cells can be fixed together by adhesive or welding, eliminating gaps between them. However, the overlap area of the battery cells will generate significant stress concentration, which can easily cause microcracks in the battery cells during the lamination process.
[0120] Therefore, in this embodiment, a buffer film 72 can be provided on the film body 71 to alleviate the stress at the overlap position of the solar cells. The size of the buffer film 72 is slightly larger than the overlap area between the solar cells. When the various parts of the photovoltaic module are stacked, the buffer film 72 can be aligned with the overlap area between the solar cells to alleviate stress. Since the solar cells are tilted at the overlap position, the direction of force on the solar cells during the lamination process forms a certain angle with the surface of the solar cells, which can easily cause excessive stress concentration at the overlap area, leading to microcracks or separation of the solar cells. Therefore, the buffer film 72 has a slope parallel to the overlap surface at the overlap position. When the solar cells are subjected to lamination pressure, the slope can provide a reaction force perpendicular to the overlap surface to alleviate stress concentration and prevent solar cell separation.
[0121] In one specific embodiment, such as Figure 2As shown, the side of the buffer membrane 72 facing away from the inclined plane is fixedly attached to the side of the membrane body 71 near the battery cell.
[0122] During the stacking process of photovoltaic modules, one side of the film body 71 can be fixed to the back sheet 6, and the other side of the film body 71 is fixedly attached to the side of the buffer film 72 that is away from the inclined surface. The inclined surface of the buffer film 72 can be aligned with the overlapping part on the cell to alleviate the stress concentration at the overlapping part.
[0123] In another specific embodiment, such as Figure 3 As shown, the side of the membrane body 71 away from the battery cell is attached to the inclined surface of the buffer membrane 72 and the two sides of the buffer membrane 72 along the length of the membrane body 71.
[0124] In this embodiment, the film body 71 can partially cover the buffer film 72. Both the side of the film body 71 away from the battery cell and the side of the buffer film 72 away from the battery cell can be fixed to the back plate 6, thereby increasing the contact area between the buffer film 72 and the film body 71 and ensuring reliable fixation between them. Furthermore, the area where the film body 71 contacts the buffer film 72 is supported by the buffer film 72 and forms a structural shape identical to that of the buffer film 72. That is, the film body 71 also forms a slope corresponding to the slope on the buffer film 72. This slope allows light to be directly incident on the inclined surface of the battery cell corresponding to the slope, improving light reflectivity.
[0125] As a specific implementation method, such as Figure 6 and Figure 7 As shown, a strip-shaped protrusion 714 is provided on the side of the film body 71 near the solar cell. The strip-shaped protrusion 714 includes a first reflective surface 7141 and a second reflective surface 7142 on both sides of the film body 71 in the width direction. The strip-shaped protrusion 714 extends in the length direction of the film body 71. Specifically, the length of the strip-shaped protrusion 714 can be equal to the length of the film body 71, and it reflects light to the solar cells on both sides through the first reflective surface 7141 and the second reflective surface 7142, respectively. Both the first reflective surface 7141 and the second reflective surface 7142 can be inclined surfaces.
[0126] As a specific implementation, the film body 71 is disposed at the edge of the photovoltaic module. The length of the first reflective surface 7141 is greater than the length of the second reflective surface 7142. The first reflective surface 7141 faces the side where the solar cells are located, so that light incident on the edge of the photovoltaic module is reflected onto the solar cells through the first reflective surface 7141. The first reflective surface 7141 can be an inclined surface, and the second reflective surface 7142 can be a surface perpendicular to the surface of the photovoltaic module, such as... Figure 7 As shown, no reflected light is required.
[0127] As a specific implementation method, such as Figure 5 As shown, the maximum thickness b of the buffer film 72 ranges from 160 to 210 μm, the length a of the inclined plane ranges from 150 to 210 mm, and the angle θ of the inclined plane ranges from 0.09° to 0.16°. This allows the buffer film 72 to achieve a better effect in relieving stress, while also avoiding increasing the thickness of the photovoltaic module.
[0128] As a specific implementation method, such as Figure 4 As shown, the film body 71 comprises, from bottom to top, an adhesive film layer 713, a substrate layer 712, and a functional layer 711. The adhesive film layer 713 is used to fix and attach to the backsheet 6 of the photovoltaic module. The adhesive film layer 713 can be heated to melt using a hot air blowing process so that the adhesive film layer 713 can adhere to the designated position on the backsheet 6. After curing, the film body 71 can be fixed to the backsheet 6.
[0129] The functional layer 711 can reflect light or trap light as a black or dark material.
[0130] The functional layer 711 may include a metal layer or an inorganic material layer, specifically a titanium dioxide layer or a glaze layer with diffuse reflection function.
[0131] This application also provides a photovoltaic module, such as... Figure 2 and Figure 3 As shown, it includes the reflective structure provided in any embodiment of this application. The photovoltaic module includes, from bottom to top, a back sheet 6, a reflective structure, a back encapsulation film 5, a battery string, a front encapsulation film 4, and a cover plate 3. The reflective structure is aligned with the string gap 14 between two adjacent battery strings to reflect the light irradiated to the string gap 14 onto the battery cells, thereby improving the photoelectric conversion efficiency of the photovoltaic module.
[0132] Specifically, the battery string includes multiple half-cells 1. Photovoltaic modules composed of half-cells 1 have advantages over conventional modules in terms of high power output, low temperature loss, and low shading loss. Each half-cell 1 includes cut portions and connecting portions formed on both sides. The connecting portion of one half-cell 1 overlaps and is fixed to the cut portion of another half-cell 1. Specifically, two half-cells 1 can be bonded or welded together.
[0133] As a specific implementation method, such as Figures 10 to 13 As shown, the connecting part is provided with a chamfer 12, and the reflective structure is provided with multiple flanges 73 on both sides in the width direction, with the flanges 73 aligned with the chamfer 12. The shape of the flanges 73 can be the same as the shape of the chamfer 12, so that light at the chamfer 12 can be reflected through the flanges 73.
[0134] Specifically, in one embodiment, such as Figure 10 and Figure 11 As shown, each half-cell 1 can be arranged in the same direction. In this case, the chamfers 12 on both sides of the string gap 14 can form a shape like... Figure 10 As shown in the diagram, the reflective structure as a whole can have a similar shape. In another embodiment, such as... Figure 12 and Figure 13 As shown, the half-cells 1 in two adjacent battery strings are arranged in opposite directions, and the chamfers 12 of the half-cells 1 on both sides of the string gap 14 can form a shape like... Figure 12 As shown in the figure, the reflective structure as a whole can have a similar shape.
[0135] The distance between two adjacent flange portions 73 can be 78–82 mm, or 103–107 mm. The length of the flange portion 73 protruding in the width direction of the reflective structure is 3–5 mm.
[0136] It is understood that the photovoltaic module also includes a busbar 8. There is a gap in the photovoltaic module at the location of the busbar 8. In order to fully utilize the light in this gap, in this embodiment, as... Figure 8 As shown, the reflective structure is aligned with the position of the busbar 8, so that light can be reflected onto the solar cells on both sides of the busbar 8 through the reflective structure, thereby improving the photoelectric conversion efficiency of the photovoltaic module.
[0137] As a specific implementation method, such as Figure 9 As shown, a first strip-shaped protrusion 715 and a second strip-shaped protrusion 716 are provided on the side of the film body 71 close to the battery cell. A first reflective part 7151 is provided on the first strip-shaped protrusion 715, and a second reflective part 7161 is provided on the second strip-shaped protrusion 716. The first reflective part 7151 and the second reflective part 7161 are respectively inclined to both sides of the busbar 8 in the width direction, so as to reflect the light irradiated to the location of the busbar 8 onto the battery cells on both sides of the busbar 8.
[0138] It is understood that the first strip protrusion 715 and the second strip protrusion 716 are symmetrically arranged in the width direction of the film body 71 so as to uniformly reflect light onto the battery cells on both sides.
[0139] As a specific implementation, the centerline of the reflective strip 7 in the length direction is aligned with the centerline of the string gap 14 in the length direction. The shape of the reflective strip 7 and the shape of the string gap 14 can be the same. In this embodiment, the reflective strip 7 is rectangular. When the centerline of the reflective strip 7 in the length direction is aligned with the centerline of the string gap 14 in the length direction, the edge of the reflective strip 7 in the width direction can slightly overlap with the projection of the edge of the battery string in the direction perpendicular to the surface of the photovoltaic module, and the overlapping areas on both sides of the reflective strip 7 are equal, so as to achieve uniform reflection of light to both sides.
[0140] Specifically, the width of the reflective strip 7 is 2 to 5 times the width of the gap 14 between the battery cells, preferably 3 or 4 times in this embodiment, to ensure sufficient reflection of light.
[0141] As a specific implementation method, the half-cell solar cell 1 can be a bifacial solar cell, which can perform photoelectric conversion on both sides, thereby further improving the photoelectric conversion efficiency.
[0142] This application also provides a method for manufacturing photovoltaic modules, such as... Figures 1 to 18 As shown, this preparation method is used to prepare the photovoltaic module provided in any embodiment of this application. The preparation method includes the following steps:
[0143] Step S1: Adhere the reflective strip 7 in the reflective structure to the back plate 6 at the set position facing the side of the battery string.
[0144] Step S2: The backplate 6 with reflective strips 7, the back sealing film 5, the battery string, the front sealing film 4, and the cover plate 3 are stacked in sequence and then processed in a subsequent process to form a photovoltaic module.
[0145] The reflective strip 7 is aligned with the gap 14 between the solar cells. When light shines on the reflective strip 7, it reflects the light onto the solar cells on both sides, so that the light shining on the gap 14 can be fully utilized, thereby effectively maximizing the photoelectric conversion efficiency of the photovoltaic module.
[0146] In addition, reflective strips 7 can also be placed on the edge of the photovoltaic module to reflect light that shines on the outside of the edge of the photovoltaic module onto the solar cells, thereby further improving the photoelectric conversion efficiency.
[0147] Specifically, step S1 includes:
[0148] Step S11: Adhere the buffer film 72 to the film body 71 to form a reflective structure.
[0149] The reflective structure includes a buffer film 72 and a film body 71. The film body 71 can be fixed to the back plate 6, and the buffer film 72 can be used to alleviate stress concentration of the battery cells in the overlapping area 11.
[0150] Step S12: Adhere the membrane body 71 to the back plate 6 at a set position facing the side of the battery string.
[0151] Specifically, step S12 includes:
[0152] Step S121: Heat the film body 71 by hot air blowing process to pre-melt the film body 71.
[0153] Step S122: Adhere the pre-molded film body 71 to the designated position on the back plate 6 and cure it.
[0154] The membrane body 71 can be slightly melted using a hot air blowing process to give its surface a certain degree of stickiness, while still maintaining its overall shape. The membrane body 71 can then be bonded to the backing plate 6 through its slightly melted surface. After static curing, a reliable bond can be achieved between the membrane body 71 and the backing plate 6.
[0155] Furthermore, prior to step S2, the preparation method further includes:
[0156] Step S2a: Cut the whole battery cell to obtain half battery cell 1.
[0157] Specifically, laser cutting technology can be used to cut a whole solar cell into two equal halves, and then the halves are welded together to form a cell string. After further processing, a half-cell solar module can be formed. Among them, half-cell solar modules have the advantages of higher power, lower temperature loss, and lower shading loss compared with conventional modules.
[0158] Step S2b: Flatten the round wire welding strip 2 radially using a flattening process to reduce the radial thickness of the round wire welding strip 2.
[0159] Step S2c: Two or more half-cell batteries 1 are welded together using round wire welding strips 2 to form a battery string.
[0160] It should be noted that, in order to eliminate the gaps between the half-cells 1, the half-cells 1 can be overlapped. However, the thickness of the overlap area of the half-cells 1 is relatively large, which increases the probability of microcracks in the half-cells 1 under lamination pressure during the lamination process. Therefore, in this embodiment, before welding, the radial thickness of the round wire welding strip 2 can be reduced, which can reduce the overall height of the overlap area, weaken the lamination stress on the half-cells 1, and thus reduce the probability of microcracks in the half-cells 1.
[0161] Furthermore, after step S2a, the preparation method further includes:
[0162] Step S2a1: A buffer layer 13 is provided at the edge of the overlapping area of the half-cell battery cell 1, such as... Figure 18 As shown.
[0163] It should be noted that after a whole solar cell is cut into half solar cells 1 using a laser, the cut portion of the half solar cell 1 will generally suffer slight cutting damage. This cutting damage can lead to the addition of hidden crack lines during lamination of the half solar cell 1. Therefore, in this embodiment, a buffer layer 13 is provided at the edge of the half solar cell 1 located in the overlapping area. This can protect the edge of the half solar cell 1, alleviate the lamination pressure on the edge of the half solar cell 1, reduce hidden crack lines, and improve the yield.
[0164] In one specific embodiment, step S2a1 specifically includes:
[0165] Step S2a11: Apply gel to the overlapping area of half-cell battery cell 1.
[0166] Step S2a12: Let half of the battery cell 1 stand still to allow the gel to solidify.
[0167] The gel can be transparent silicone, POE film, or EVA film, etc. When applying the gel, it can be in a hot-melt state. After application, the gel can be cured and shaped to achieve adhesion and fixation with the half-cell battery cell 1.
[0168] The half-cell battery cell 1 can be left to stand for 2 to 4 hours to ensure that the gel can fully solidify, thereby ensuring a reliable connection with the half-cell battery cell 1.
[0169] In another specific embodiment, step S2a1 specifically includes:
[0170] Solid film is used to adhere to the overlapping area of half of the battery cell 1.
[0171] The film can be directly bonded to half of the battery cell 1 without long-term static curing. In addition, the film has a buffering effect, and the half of the battery cell 1 will not stick to each other after the film is applied.
[0172] The thickness of the buffer layer 13 can be 1–100 μm. Within this thickness range, the buffer layer 13 can provide buffering protection without increasing the overall thickness of the battery string. In this embodiment, the thickness of the buffer layer 13 is preferably 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm.
[0173] Furthermore, the width of the buffer layer 13 can be 0.2–2 mm. Within this thickness range, a reliable connection between the buffer layer 13 and the half-cell battery 1 can be ensured, while avoiding large-area shading of the half-cell battery 1. In this embodiment, the width of the buffer layer 13 can be 0.5 mm, 0.8 mm, 1.2 mm, 1.5 mm, or 1.8 mm.
[0174] Furthermore, step S2b specifically includes:
[0175] Step S2b1: A flattening process is used to radially flatten the portion of the round wire welding strip 2 corresponding to the overlapping area, thereby reducing the radial thickness of the portion of the round wire welding strip 2 corresponding to the overlapping area. Figures 15 to 17 As shown.
[0176] The welding strip can be cylindrical and have a relatively long length. The portion of the welding strip corresponding to the overlap area can be flattened using a flattening process, while the portion of the welding strip outside the overlap area can still maintain its cylindrical shape, thus simplifying the processing of the weld joint.
[0177] Furthermore, step S2b specifically includes:
[0178] A flattening process is used to flatten the portion of the round wire welding strip 2 corresponding to the overlap area in the radial direction, so that the radial thickness of the portion of the round wire welding strip 2 corresponding to the overlap area is reduced to 1 / 3 to 1 / 2 of the diameter of the round wire welding strip 2. This reduces the overall height of the half cell 1 in the overlap area by more than half, weakens the lamination stress of the half cell 1, and reduces microcracks.
[0179] Furthermore, after step S2b, the preparation method further includes:
[0180] Step S2b2: Heat the round wire welding strip 2 according to the annealing temperature of the material.
[0181] Step S2b3: Cool down the heated round wire welding strip 2.
[0182] Heating the round wire welding strip 2 to its annealing temperature eliminates the work hardening effect and reduces its stress. In this embodiment, the main material of the round wire welding strip 2 is copper, and its annealing temperature is 550℃~650℃, specifically, the round wire welding strip 2 can be heated to 600℃. The heated round wire welding strip 2 is then cooled to facilitate subsequent string welding operations.
[0183] Specifically, the round wire welding strip 2 can be cooled using either air cooling or water cooling. Air cooling is time-consuming; therefore, water cooling is preferred in this embodiment, as it can complete the cooling process in a shorter time, thus improving the processing efficiency of the round wire welding strip 2.
[0184] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A light reflecting structure, characterized by, The reflective structure consists of at least one reflective strip (7) extending along the length of the battery string. The reflective strip (7) is used to reflect light located at the gap (14) in the photovoltaic module and / or light at the edge of the photovoltaic module onto the battery cells. The length of the reflective strip (7) is greater than or equal to the length of the gap (14). The reflective strip (7) includes a film body (71) and at least one buffer film (72). The buffer film (72) is fixedly disposed on the film body (71). The buffer film (72) includes an inclined surface. The side of the film body (71) away from the battery cell is attached to the inclined surface and the buffer film (72) on both sides of the film body (71) along its length. The inclined surface corresponds to the overlapping surface of two adjacent battery cells, and the inclined surface is parallel to the overlapping surface.
2. The light reflecting structure of claim 1, wherein The reflective structure is composed of two or more reflective strips (7), each reflective strip (7) is parallel to each other, and there is an equal distance between two adjacent reflective strips (7).
3. The light reflecting structure of claim 1, wherein, The film body (71) has a strip-shaped protrusion (714) on one side near the battery cell. The strip-shaped protrusion (714) includes a first reflective surface (7141) and a second reflective surface (7142) on both sides of the width direction of the film body (71).
4. The light reflecting structure of claim 3, wherein, The film body (71) is disposed on the edge of the photovoltaic module, the length of the first reflective surface (7141) is greater than the length of the second reflective surface (7142), and the first reflective surface (7141) faces the side where the battery cell is located.
5. The light reflecting structure of claim 1, wherein The maximum thickness (b) of the buffer membrane (72) ranges from 160 to 210 μm, the length (a) of the inclined surface ranges from 150 to 210 mm, and the angle (θ) of the inclined surface ranges from 0.09° to 0.16°.
6. The light reflecting structure according to any one of claims 1-5, characterized in that The film body (71) includes, from bottom to top, an adhesive film layer (713), a substrate layer (712) and a functional layer (711). The adhesive film layer (713) is used to fix and attach to the back sheet (6) of the photovoltaic module.
7. The light reflecting structure of claim 6, wherein, The functional layer (711) includes a metal layer or an inorganic material layer.
8. The reflective structure according to claim 7, characterized in that, The functional layer (711) is a titanium dioxide layer or a glaze layer.
9. A photovoltaic module, characterized in that, The photovoltaic module includes the reflective structure according to any one of claims 1-8, and from bottom to top, the photovoltaic module includes a back sheet (6), the reflective structure, a back encapsulation film (5), a battery string, a front encapsulation film (4), and a cover plate (3), wherein the reflective structure is aligned with the string gap (14) between two adjacent battery strings.
10. The photovoltaic module of claim 9, wherein, The battery string includes multiple half-cell battery pieces (1), each half-cell battery piece (1) having a cut portion and a connecting portion formed on both sides of the half-cell battery piece (1), wherein the connecting portion of one half-cell battery piece (1) overlaps and is fixed to the cut portion of the other half-cell battery piece (1).
11. The photovoltaic module of claim 10, wherein, The connecting part is provided with a chamfer (12), and the reflective structure is provided with a plurality of flanges (73) on both sides in the width direction, and the flanges (73) are aligned with the chamfer (12).
12. The photovoltaic module of claim 11, wherein, The distance between two adjacent flange portions (73) is 78~82mm, or 103~107mm.
13. The photovoltaic module of claim 11, wherein, The flange portion (73) protrudes for a length of 3mm to 5mm in the width direction of the reflective structure.
14. The photovoltaic module according to claim 9, characterized in that, The photovoltaic module also includes a busbar (8), and the reflective structure is aligned with the position of the busbar (8).
15. The photovoltaic module of claim 14, wherein, The film body (71) has a first strip-shaped protrusion (715) and a second strip-shaped protrusion (716) on the side near the battery cell. The first strip-shaped protrusion (715) has a first reflective part (7151), and the second strip-shaped protrusion (716) has a second reflective part (7161). The first reflective part (7151) and the second reflective part (7161) are respectively inclined to both sides of the busbar (8) in the width direction, so as to reflect the light irradiated to the location of the busbar (8) onto the battery cells on both sides of the busbar (8).
16. The photovoltaic module of claim 9, wherein, The center line of the reflective structure in the length direction is aligned with the center line of the string gap (14) in the length direction.
17. The photovoltaic module of claim 9, wherein, The width of the reflective strip (7) is 2 to 5 times the width of the gap (14) between the battery cells.
18. The method of preparing a photovoltaic module according to any of claims 10-17, wherein, The half-cell (1) is a bifacial solar cell.
19. A method for manufacturing a photovoltaic module, characterized in that, The method for preparing the photovoltaic module according to any one of claims 9-18 comprises the following steps: The reflective strip (7) in the reflective structure is glued to a set position on the back plate (6) facing one side of the battery string; The backplate (6) with the reflective strip (7) attached, the back sealing film (5), the battery string, the front sealing film (4) and the cover plate (3) are stacked in sequence and then processed through a subsequent process to form the photovoltaic module.
20. The photovoltaic module production method of claim 19, wherein, The step of attaching the reflective strip (7) in the reflective structure to a predetermined position on the back plate (6) facing one side of the battery string specifically includes: The buffer film (72) is bonded to the film body (71) to form the reflective structure; The membrane body (71) is bonded to a set position on the back plate (6) facing one side of the battery string.
21. The method of making a photovoltaic assembly of claim 19, wherein, Before the backplate (6) with the reflective structure adhered to it, the back sealing film (5), the battery string, the front sealing film (4), and the cover plate (3) are sequentially stacked and processed through subsequent steps to form the photovoltaic module, the method further includes: The entire solar cell is cut to obtain half solar cells (1). The round wire welding strip (2) is flattened radially using a flattening process to reduce the radial thickness of the round wire welding strip (2); Two or more of the half-cells (1) are welded together by the circular wire welding strip (2) to form the battery string.
22. The method of claim 21, wherein the method further comprises: After cutting the entire battery cell to obtain half battery cells (1), the method further includes: A buffer layer (13) is provided at the edge of the overlapping area of the half-cell (1).
23. The method of making a photovoltaic assembly of claim 22, wherein, The provision of a buffer layer (13) in the overlapping area of the half-cell battery (1) specifically includes: Apply gel to the overlapping area of the half-cell (1); The half-cell battery (1) is left to stand to allow the gel to solidify.
24. The method for preparing a photovoltaic module according to claim 23, characterized in that, The half-cell battery (1) is left to stand for 2 to 4 hours.
25. The method for preparing a photovoltaic module according to claim 22, characterized in that, The provision of a buffer layer (13) in the overlapping area of the half-cell battery (1) specifically includes: Solid film is used to adhere to the overlapping area of the half-cell battery cell (1).
26. The method for preparing a photovoltaic module according to any one of claims 22-25, characterized in that, The thickness of the buffer layer (13) is 1~100um.
27. The method of preparing a photovoltaic assembly according to any of claims 22-25, wherein, The width of the buffer layer (13) is 0.2~2mm.
28. The method of making a photovoltaic assembly of claim 22, wherein, The method of flattening the round wire welding strip (2) radially to reduce the radial thickness of the round wire welding strip (2) specifically includes: A flattening process is used to flatten the portion of the round wire welding strip (2) corresponding to the overlapping area in the radial direction, so as to reduce the radial thickness of the portion of the round wire welding strip (2) corresponding to the overlapping area.
29. The method of making a photovoltaic assembly of claim 28, wherein, The method of flattening the round wire welding strip (2) radially to reduce the radial thickness of the round wire welding strip (2) specifically includes: The portion of the round wire welding strip (2) corresponding to the overlapping area is flattened radially using a flattening process, so that the radial thickness of the portion of the round wire welding strip (2) corresponding to the overlapping area is reduced to 1 / 3 to 1 / 2 of the diameter of the round wire welding strip (2).
30. The method of making a photovoltaic assembly of claim 22, wherein, After flattening the round wire strip (2) radially using a flattening process to reduce the radial thickness of the round wire strip (2), the method further includes: The round wire welding strip (2) is heated according to the annealing temperature of the material. The heated round wire welding strip (2) is cooled down.
31. The method of making a photovoltaic assembly of claim 30, wherein, The cooling process for the heated round wire welding strip (2) specifically includes: The round wire welding strip (2) is cooled by air cooling or water cooling.
32. The method of making a photovoltaic assembly of claim 20, wherein, The step of bonding the membrane body (71) to the back plate (6) at a predetermined position facing one side of the battery string specifically includes: The film body (71) is heated by a hot air blowing process to pre-melt the film body (71); The pre-molded film body (71) is bonded to a designated position on the back plate (6) and then cured.