Method for manufacturing photovoltaic module applied to surface having biaxial curvature

Abstract

To provide a technology for manufacturing a flexible photovoltaic module adaptable to a surface having biaxial curvature.SOLUTION: A method manufactures a flexible photovoltaic panel (1) to be fixed to a support surface (R) of biaxial curvature. The method includes the steps of: generating a numerical model of a flat structure curved to conform the support surface (R); identifying, in the flat structure, compression zones which are subject to formation of creases or lifting as a result of curvature imposed by the support surface (R); determining a pattern of a photovoltaic cells to be arranged on the flat structure; manufacturing a flat photovoltaic panel (1) on the basis of the pattern of the photovoltaic cells; and forming cut-outs (104, 105) in the compression zones, the cut-outs being configured to close as a result of the curvature imposed by the support surface (R).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a photovoltaic module, and more particularly to a photovoltaic module that can be applied to a curved surface.

Background Art

[0002] Recently, the advantages of solar energy have been known. It has become increasingly common to generate electrical energy using this clean and renewable non-fossil energy source. In recent years, photovoltaic technology has become less expensive as a result of efficiency improvements and cost reductions associated with increased production, and government incentives have also given it a boost. On the other hand, the electrification of automobiles is advancing at an ever-faster pace. In this regard, the use of solar energy to at least partially power electric or hybrid vehicles has attracted attention. In order to apply photovoltaic modules to automobiles in a satisfactory manner, it is necessary to consider that the surfaces of these automobiles generally have double curvature, i.e., biaxial curvature. Although this problem is illustrated in this specification by way of an example of application in the automotive field, it is actually a widespread problem. That is, photovoltaic modules are usually manufactured using laminates and generally have a flat structure. The most common photovoltaic modules are composed of a flat panel of glass and an aluminum frame, and are thus essentially rigid. Even flexible photovoltaic panels in which the glass is replaced by a polymer cannot be applied to a surface with double curvature for morphological reasons.

[0003] It is of course possible to construct a photovoltaic module with double curvature using typical glass-curving techniques or by injecting resin into a mold, but the cost is higher compared to the normal manufacture of photovoltaic modules with a planar lamination apparatus. These techniques need to be based on the manufacture of molds, and a new mold is required each time the surface covered by the photovoltaic module is renewed, so the degree of freedom of the final result is limited.

[0004] The Ford C-Max Energi, unveiled in 2014, is an example of a solar roof for passenger cars, where supports for photovoltaic modules are positioned on the car's roof and designed to deform from a double-curvature roof to a single-curvature roof. While flexible photovoltaic modules are easily applicable, this substantially alters both the vehicle's weight and aerodynamics. An example of replacing a car roof with a rigid, double-curvature photovoltaic module has been proposed by a2-solar GmbH and implemented in some Toyota and Hyundai models. The Japanese company Teijin has made a recent announcement in this field, developing a curved roof using polycarbonate instead of glass. This product is also manufactured using thermoforming with appropriately curved molds. It's important to note that all examples relate to products for original equipment (OEM) parts and cannot be applied to roofs already on the market, i.e., aftermarket cars.

[0005] U.S. Patent No. 4,717,790 describes a method for manufacturing a curved photovoltaic module from a glass surface pre-curved to the shape and size of a roof to be replaced. U.S. Patent Application Publication No. 2017 / 0141253 further improves this module and discusses a method for reducing stress on connections between individual cells by arranging cells in groups along one curvature or another.

[0006] Methods that do not use glass or other pre-curved transparent materials are described in European Patent Publication No. 3712964 and Dutch Patent Invention No. 2021711. In the method described in European Patent Publication No. 3712964, the curvature of at least one of the two surfaces of the panel is obtained by a resin injection molding process. In the method described in Dutch Patent Invention No. 2021711, the idea of ​​dividing the cells into multiple groups is used, starting with individual lamination steps that consider single curvature, and then combining everything in the final process to create a surface with biaxial curvature. These two methods are slower and more complex in terms of mold and lamination techniques than the techniques used to construct standard photovoltaic modules, namely techniques based on the use of planar vacuum lamination equipment. This results in higher costs for the process of manufacturing the aforementioned solar roofs. Furthermore, all of these techniques are suitable for manufacturing original equipment solar roofs, but not for the market of vehicles already in circulation.

[0007] U.S. Patent Publication 2014 / 0130848 describes how flexible photovoltaic modules can be applied to a double-curvature surface by forming longitudinal notches in the polymer material of the panel. Thus, the panel can be partially deformed to conform to the convex double curvature of the roof. A drawback of this technique is that it is not effective for all curvatures because the notches conform to the shape of the cells, not the shape of the roof. Another drawback is that widening the notches to allow deformation causes the cells to move away from each other, resulting in a lower cell density on the final roof surface than the density achieved when the spacing between cells is minimized. Finally, the described process is completed by bonding the cut panels to a pre-curved convex transparent surface that forms a single, unified outer surface of the roof. This highlights the need to use different molds for each individual roof model.

[0008] Therefore, an object of the present invention is to provide a technology for manufacturing a flexible photovoltaic module that can be adapted to a surface having biaxial curvature, and this technology is based on conventional methods for manufacturing photovoltaic modules using a flat lamination apparatus. [Overview of the project]

[0009] According to the present invention, a method for manufacturing a flexible photovoltaic panel that is fixed to a support surface with double curvature, A numerical model of a flat structure that is curved to match the aforementioned support surface is generated. In the flat structure, a compression region is identified in which folds or lifts are likely to form as a result of the curvature provided by the support surface. Determine the pattern of photovoltaic cells arranged on the aforementioned flat structure. A flat solar panel is manufactured based on the pattern of the solar cell. A notch is formed in the compression region, configured to close as a result of the curvature provided by the support surface. This includes, The pattern comprises a plurality of blocks of photovoltaic cells separated from each other by the compression region, and in each block containing a plurality of cells, adjacent cells have a shorter distance from each other than adjacent cells separated by one of the compression regions. The aforementioned solar power generation panel is A plurality of photovoltaic cells arranged according to the aforementioned pattern of photovoltaic cells, A sealing layer configured to house the aforementioned photovoltaic cells, It comprises a flexible plastic material, and at least one surface layer that is bonded to the encapsulation layer on the first surface of the encapsulation layer, overlaps with the encapsulation layer, and is exposed to sunlight during use. To provide a method that includes [this].

[0010] This invention is based on the observation that applying a flat surface to a surface with double curvature results in deformation of the first surface having compression and expansion regions. If the material forming the photovoltaic module does not deform sufficiently, problems such as creases and lifting occur in the compression regions, preventing the photovoltaic module from adhering to the surface with double curvature. Therefore, this invention is based on appropriately shaping the outline of the photovoltaic module to reduce or eliminate compression regions when the module or panel is applied to a surface with double curvature. The photovoltaic module thus folds seamlessly into this surface and can cover this curved surface as completely as possible. In particular, the photovoltaic module can be applied to existing surfaces such as the roofs of automobiles in circulation and may therefore be designed as an aftermarket product.

[0011] Another subject of the present invention is a flexible photovoltaic panel fixed to a support surface with double curvature, Multiple solar cells arranged according to a pattern of solar cells, A sealing layer configured to house the aforementioned photovoltaic cells, It comprises a flexible plastic material, and at least one surface layer that is bonded to the encapsulation layer on the first surface of the encapsulation layer, overlaps with the encapsulation layer, and is exposed to sunlight during use. Equipped with, The material comprises a flexible material and selectively includes at least one backing layer that is bonded to the encapsulation layer on a second surface of the encapsulation layer opposite to the first surface and overlaps with the encapsulation layer, The pattern comprises multiple blocks of photovoltaic cells separated from each other by compression regions, and in each block containing multiple cells, adjacent cells have a shorter distance from each other than adjacent cells separated by one of the compression regions. The aforementioned encapsulation layer is formed by a first layer and a second layer, which are arranged on both sides of the plurality of photovoltaic cells and bonded around the photovoltaic cells. The panel is configured such that the notches penetrating the encapsulation layer, surface layer, and back layer are formed in the compression region, and the notches are configured to close as a result of the curvature provided by the support surface.

[0012] The present invention will be described by several preferred embodiments provided with reference to the accompanying drawings as non-limiting examples. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic cross-sectional view of a part of a solar power generation panel according to the present invention. [Figure 2] Schematic cross-sectional view of a modified example of the solar power generation panel shown in Figure 1. [Figure 3] Block diagram showing the main steps of the method for manufacturing a solar power generation panel according to the present invention. [Figure 4] Diagram showing a flat structure model to illustrate the overall shape of a solar power generation panel. [Figure 5] Figure 4 shows a model with the arrangement of solar power cells applied. [Figure 6] This diagram shows a portion of a solar power generation panel with a notch, in a solar power generation panel with a flat configuration. [Figure 7] This diagram shows a portion of a photovoltaic panel with a notch, applied to a support surface with double curvature. [Modes for carrying out the invention]

[0014] Figure 1 is a diagram of the layers constituting the flexible solar power generation panel according to the present invention. According to this diagram of the layers, the flexible solar power generation module is generally indicated by reference numeral 1, and essentially includes a plurality of solar power generation cells 2 arranged side by side, at least one encapsulation layer 3 made of a thermoplastic material and configured to accommodate the solar power generation cells 2 therein, at least one front layer 4 joined to and overlapping the encapsulation layer 3 on the first surface of the encapsulation layer 3, and at least one back layer 6 joined to and overlapping the encapsulation layer 3 on the second surface of the encapsulation layer 3 opposite to the first surface. The solar power generation cells 2 are cells made of, in particular, single crystal silicon or polycrystalline silicon. According to a preferred embodiment, the solar power generation cells 2 are "back contact" cells in which all the contacts (not shown) are formed on the back side of the cells. The encapsulation layer 3 is formed by a first layer 3a and a second layer 3b arranged on both sides of the solar power generation cells 2 and attached around the cells. The front layer 4 is exposed to sunlight during use. At least one front layer 4 is made of a flexible plastic material. At least one back layer 6 is made of a flexible material.

[0015] According to an embodiment not shown, the back layer 6 may not be provided.

[0016] In this specification, the terms "front" and "back" refer to the state of use of the solar power generation panel. The "front" layer faces the sunlight and is arranged between the light source and the encapsulation layer 3 that houses the solar power generation cells. On the other hand, the "back" layer is arranged on the opposite side to the encapsulation layer that houses the cells.

[0017] The flexible photovoltaic module is manufactured according to the conventional manufacturing technology by the following steps: selecting photovoltaic cells based on electrical parameters, welding the photovoltaic cells to each other to form a series of electrically connected cells known as a string, combining the strings into a certain shape, usually a rectangular shape, to form a photovoltaic module with desired dimensions, simultaneously forming electrical contacts for extracting the generated current from the completed module, stacking the various layers according to the arrangement in FIG. 1, and laminating in a flat vacuum laminator according to the temperature cycle corresponding to the materials used. The welding is performed using a tin-plated copper metal part, which ensures good conductivity.

[0018] The lamination usually requires a cycle time of 10 to 20 minutes and is currently the most reliable, rapid, and economical process for manufacturing photovoltaic modules based on single-crystalline silicon or polycrystalline silicon.

[0019] FIG. 2 shows a modified example of the layers shown in FIG. 1. In this modified example, the back layer 6 includes a conductive backsheet 7, that is, a metal film formed to create an electrical circuit in which the photovoltaic cells 2 are connected, and is housed inside the back layer 6. In the modified example of FIG. 2, since the individual cells are directly connected to the conductive backsheet 7 that makes the overall electrical contacts of the photovoltaic module, the manufacturing process does not include the creation of a string of welded cells. The other steps of the above-described process are the same. According to the modified example of FIG. 2, since the linear shape of the column (string) is replaced with a more free arrangement, a more free arrangement of the photovoltaic cells can be obtained more easily. This can be more easily realized by using back-contact cells.

[0020] Referring to Figures 3 to 7, a method for manufacturing a flexible photovoltaic panel 1 that can be fixed to a support surface with double curvature, such as the roof of an automobile, is described. The support surface is indicated by the letter R in Figure 7. The support surface may be convex, as in the illustrated example. However, the present invention also includes concave or saddle-shaped support surfaces. The photovoltaic panel 1 is bonded to the support surface R by a backing layer 6. If the backing layer 6 is absent, the photovoltaic panel 1 is bonded to the support surface R by an encapsulation layer 3.

[0021] First, a numerical model of a flat structure that is curved to match the support surface is generated (step 10 in Figure 3). This modeled flat structure is schematically shown in Figure 4 and is denoted by reference numeral 101.

[0022] Considering that the photovoltaic module 1 is curved along a support surface R with double curvature, it is necessary to consider the deformation required to conform module 1 to the support surface R. This may be done theoretically using a three-dimensional modeling system such as Rhinoceros software developed by Robert McNeel & Associates, which allows us to examine the compression and expansion regions of the flat structure that is curved to adhere to a surface with two-dimensional curvature.

[0023] Next, in the modeled flat structure 101, compression regions are identified where folds or lifts are likely to form as a result of the curvature given by the support surface R (step 20 in Figure 3). These regions are roughly shown in Figure 4 using dashed lines and are represented by reference numerals 102 and 103. Thus, as will be described later, it is possible to shape the edges of the photovoltaic module in such a way that excess surface material, i.e., material that would form folds or other deformations after bending, is removed.

[0024] Next, the pattern of photovoltaic cells to be arranged on the flat structure 101 is determined. This pattern comprises multiple blocks of photovoltaic cells (represented by 111 to 118 in Figure 5) separated from each other by the compression regions 102 and 103 determined in the previous step. In each block of cells (for example, each block 111 or block 112), adjacent cells have a shorter mutual distance than adjacent cells separated by the compression regions 102 and 103 (for example, adjacent cells separated by the upper left compression region in Figures 4 and 5 (represented by reference numeral 102 in Figure 4) (the cells in block 111 and the cells in block 112)).

[0025] Next, a photovoltaic panel having photovoltaic cells 2 arranged based on the photovoltaic cell pattern determined in step 30 is manufactured according to the lamination process described above (step 40 in Figure 3).

[0026] Next, as described above, notches 104 and 105 are formed in the compression regions 102 and 103 to remove excess material (step 50 in Figure 3). Doing so optimizes the initial shape of the photovoltaic module by creating empty spaces (notches 104 and 105, see Figure 6) that tend to close when a double curvature is given (see Figure 7). This allows for maximum coverage of the final surface radius, even if starting with a flat photovoltaic module. In fact, the initial photovoltaic module has a larger surface area than the curved surface to be covered. The notches 104 and 105 are formed starting from the edges of the photovoltaic panel 1 and oriented in directions perpendicular to each other.

[0027] Whether the ends of a photovoltaic module can be freely shaped clearly depends on the presence or absence of cells that have the correct shape and cannot be cut again. Therefore, it is necessary to start by finding a compromise between the arrangement of cells and the requirement for a shape that depends on the specific curvature to be obtained. Accordingly, it is understood that the method described for manufacturing a photovoltaic module according to the modified example shown in Figure 2 is more suitable for the purposes of the present invention.

[0028] The photovoltaic panel 1 described above may be fixed to the support surface R by a method known in itself, for example, by mechanical means or by adhesive, such that the backing layer 6 (or the encapsulation layer 3 if the backing layer 6 is absent) is bonded to the support surface R. According to one embodiment, in order to facilitate the application of the photovoltaic panel 1 to a support surface R made of iron, more generally a ferromagnetic support surface, the backing layer 6 may include a magnetic material, in particular a permanent magnet.

[0029] The advantages of the present invention for industrial manufacturing purposes are clear. It is no longer necessary to create separate molds for each surface type using thermoforming or injection molding. The optimal shape of the photovoltaic module may be numerically determined, and the edges of the photovoltaic module can be easily formed using numerically controlled cutters, allowing for the manufacture of photovoltaic modules using the efficient, fast, and economical methods described above. Finally, the present invention makes it possible to create photovoltaic modules applicable to already-commercial automobiles by bonding the modules to the roof.

[0030] As a further development, adhesive seals having the function of sealing the notches from the upper side exposed to air fluid friction may be applied to notches 104 and 105, and simultaneously, for aftermarket applications, notches 104 and 105 may be used to mechanically fasten the module to the roof of an automobile. These seals may be pre-molded to have the shape of the notches, or they may be made on a case-by-case basis using adhesive resin.

[0031] The application of photovoltaic modules can be facilitated by using vacuum technology, i.e., by compressing the modules and applying vacuum bags to them to ensure uniform adhesion to a double-curvature surface. In this process, if thermoplastic resin is used, heat may be applied (e.g., using a radiant lamp) to facilitate adhesion to the module surface.

Claims

1. A method for manufacturing a flexible photovoltaic panel (1) fixed to a support surface (R) of double curvature, comprising the steps of: generating a numerical model of a flat structure (101) that is curved to conform to said support surface (R); identifying compression areas (102, 103) in said flat structure that are prone to the formation of folds or lifts as a result of the curvature imparted by said support surface (R); determining a pattern of photovoltaic cells to be placed on the planar structure; Manufacturing a flat solar panel (1) based on the pattern of the solar cell; forming notches (104, 105) in said compression area that are configured to close as a result of the curvature provided by said support surface (R); Including, the photovoltaic cell pattern comprises a plurality of blocks (111-118) of photovoltaic cells separated from one another by the compressed regions (102, 103), adjacent cells in each block of cells having a shorter mutual distance than adjacent cells separated by one of the compressed regions; The solar power generation panel is A plurality of photovoltaic cells (2) arranged according to the pattern of the photovoltaic cells; an encapsulation layer (3) configured to house the photovoltaic cell therein; at least one surface layer (4) comprising a flexible plastic material, bonded to and overlapping the encapsulation layer on a first surface of the encapsulation layer (3), and exposed to sunlight in use; A method comprising:

2. The photovoltaic panel further comprises at least one backing layer (6) comprising a flexible material and bonded to and overlapping the encapsulation layer on a second side of the encapsulation layer opposite the first side; The method of claim 1 , wherein the notch extends through the at least one backing layer.

3. A flexible photovoltaic panel fixed to a support surface (R) of double curvature, a plurality of photovoltaic cells (2) arranged according to a photovoltaic cell pattern; an encapsulation layer (3) configured to house the photovoltaic cell therein; at least one surface layer (4) comprising a flexible plastic material, bonded to and overlapping the encapsulation layer on a first surface of the encapsulation layer (3), and exposed to sunlight in use; Equipped with the pattern of photovoltaic cells comprises a plurality of blocks (111-118) of photovoltaic cells separated from one another by compressed regions (102, 103), adjacent cells in each block of cells having a shorter mutual distance than adjacent cells separated by one of the compressed regions; A panel, wherein a notch (104, 105) passing through the encapsulation layer and the face layer is formed in the compression region, the notch being configured to close as a result of a curvature imparted by the support surface.

4. and at least one backing layer (6) comprising a flexible material and bonded to and overlapping the encapsulating layer on a second side of the encapsulating layer opposite the first side; The panel of claim 3 , wherein the cutout extends through the at least one backing layer.

5. The panel according to claim 4, wherein said at least one back layer comprises a conductive backsheet (7).

6. The panel of claim 4 , wherein the at least one backing layer comprises a magnetic material.

7. The panel of claim 3 , wherein the photovoltaic cells have electrical contacts on a back side of the photovoltaic cells.

8. The panel of claim 3 , further comprising an adhesive seal disposed within the cutout and configured to mechanically secure the photovoltaic panel to the support surface.

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