Method for manufacturing a photovoltaic module

Abstract

To provide a method of manufacturing a colored photovoltaic module having desired coloration.SOLUTION: A method of manufacturing a photovoltaic module (1) comprising at least a first layer and a second layer affixed to each other by means of an encapsulant comprises steps of: providing a lamination device; disposing the first layer in the lamination device; and disposing an encapsulant material on the first layer. Manufacture of the encapsulant material comprises steps of: providing a base resin comprising a silane-modified polyolefin and having a melting point below 90°C; and forming a mixture of the base resin, pigment particles and an additive that comprises a crosslinking catalyst, the cross-linking catalyst being present in a proportion of 0.01 to 5 parts per 100 of the resin.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic devices. More particularly, the present invention relates to a method for manufacturing a colored photovoltaic module suitable for incorporation into buildings.

[0002] Photovoltaic (PV) devices - also called solar cells or solar panels - tend to be a color close to black. Usually in a purple or blue hue, a clearly defined pattern of individual cells is visible. When such PV devices are installed in a building, such PV devices are obtrusive and for this reason are usually difficult to tolerate for direct use as building cladding.

[0003] To solve this problem, colored PV devices that can be incorporated into building structures - especially as external cladding - have been proposed.

[0004] Patent Document 1 discloses a film provided on the front sheet of a PV device to modify the appearance of the module. However, this film requires a specific profile that requires alignment with the geometry of the individual PV cells that make up the module and relies on a complex design that includes facets within the front sheet and embedded elements within the inactive portions of the module.

[0005] Patent Document 2 discloses a PV device that includes a graphic film provided inside the module. This film is printed to have a color or texture and requires a selective reflective layer to limit the impact of the film on the efficiency of the module.

[0006] Patent Documents 3 and 4 disclose decorative film overlays provided on or inside PV modules such as Patent Documents 5 and 6.

[0007] Patent Document 7 discloses a white photovoltaic module in which an interference filter is formed on an intermediate layer provided on the light incident surface of a photovoltaic module so as to reflect a certain amount of light over the entire visible spectrum. Special devices and methods are required to produce this interference film.

[0008] However, all of these prior art solutions are either complex or require additional layers to be provided to the module. In essence, for each of the additional layers added to the module, an interface exists between the plurality of separable layers, so the risk of delamination of the module increases. Furthermore, there may be a need for special manufacturing techniques or devices.

[0009] Patent Document 8 proposes a solution to this problem. In the embodiment of FIG. 7 of Patent Document 8, the front sealing layer itself contains pigment particles randomly dispersed therein. This therefore does not require an additional colored film in addition to the front sealing layer, but causes a completely different set of problems. The sealant used in Patent Document 8 is a conventional one and is laminated at a conventional lamination temperature on the order of 130° C. to 170° C. under a pressure of up to 1 bar, so the pigment particles may migrate during lamination. For this reason, the color matching becomes significantly non-uniform. Furthermore, in extreme cases, the excessive flow of the sealant causes significant variations in thickness - especially between the regions where the PV cells are present and where they are not present - within the module. As a result, although it is repetitive, the color varies across the entire module.

[0010] Second, standard temperature and pressure are compatible with most PV cell technologies, such as thin-film silicon, crystalline silicon, and germanium-based cells, but typically not with typical perovskite-based organic and dye-sensitized cells. These latter types of cells, also known as Grätzel cells, utilize a photosensitive dye adsorbed on a thin film of titanium dioxide and employ a liquid or gel-based electrolyte. The liquid or gel-based electrolyte is at risk of damage when heated to temperatures above 90°C. Therefore, these latter types of cells are not compatible with conventional lamination methods. Perovskites are similarly sensitive to heat, although to a lesser extent.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Summary of the Invention

Problems to be Solved by the Invention

[0012] Accordingly, an object of the present invention is to provide a method for manufacturing a colored photovoltaic module having a desired color scheme, and as a second consideration, to propose a method that is compatible with dye-sensitized, perovskite, and other temperature-sensitive photovoltaic technologies. Means for Solving the Problems

[0013] More specifically, the present invention relates to a method for manufacturing a solar cell module including at least a first layer and a second layer fixed to each other by a sealing body. Of course, even if the photovoltaic module includes a photoelectric conversion element, the photoelectric conversion element does not necessarily have to be either the first layer or the second layer, but it may be either one. The method includes providing a laminating device such as a vacuum bag laminating device, providing the first layer, which is either alone or as an existing prefabricated PV module or a part of the PV module, such as a front sheet, a back sheet, or another layer, in the laminating device, (a) providing a base resin having a melting point of less than 90°C and containing a silane-modified polyolefin (e.g., an ethylene-containing copolymer); (b) generating a mixture of an additive containing a crosslinking catalyst present in a proportion of 0.01 to 20, preferably 0.01 to 5 parts per 100 parts of the resin, the base resin, and pigment particles of a convenient type, size, and concentration; (c) melting the mixture at a temperature of 90°C to 190°C, preferably 160°C to 180°C; and (d) extruding the mixture to form a sealing material, and providing the sealing material that can be provided as a sheet and / or powder on the first layer, providing the second layer, which is, for example, a photoelectric conversion device, an internal front sheet constituting a part of an existing PV module, or an appropriate other layer, on the sealing material, laminating the first layer, the second layer, and the sealing material while applying heat and pressure applied at a temperature of 60°C to 125°C, preferably 60°C to 100°C, more preferably 70°C to 90°C, so as to crosslink the base resin.

[0014] During lamination at a temperature of up to 125°C, at least a part of the above-mentioned encapsulating resin can be cross-linked. As a result, mechanical properties suitable for use in a PV module - specifically, sufficient rigidity and creep resistance at the highest expected supply temperature (i.e., about 85°C, up to 105°C taking into account a safety margin) - are obtained. The cross-linking may also be carried out or continued after the lamination of the module is completed.

[0015] As a result of the processing temperature being lower than normal, the viscosity during lamination becomes higher than normal and the tangent delta becomes lower than normal. This not only prevents migration and aggregation of the dye particles, but also prevents excessive inflow of the colored encapsulant. As a result, the color scheme of the module becomes uniform. This result is surprising and shows an unexpected synergistic effect between the low-temperature treatment and the use of the dye for coloring the module.

[0016] Furthermore, combining such a specific encapsulant with a temperature lower than the normal lamination temperature is suitable not only for laminating conventional PV modules in a conventional lamination apparatus, but also for use when laminating PV modules containing temperature-sensitive PV cells - such as perovskite cells, organic cells, or dye-sensitized cells. Also, the reduction in the processing temperature during lamination results in a decrease in energy consumption. Note that one of the above-mentioned first layer and second layer may constitute a part of an existing pre-manufactured PV module on which other layers are laminated, or may be an individual layer of the PV module.

[0017] An alternative method according to the present invention is providing a lamination apparatus, and providing the first layer (described above) in the lamination apparatus, and A step of providing a sealing material in a powder state on the first layer, which is realized by: (a) providing a base resin having a melting point of less than 90 °C and containing a silane-modified polyolefin (for example, an ethylene-containing copolymer) in a powder state; and (b) mixing at least a powder or liquid additive containing a crosslinking catalyst present in the sealing material at a ratio of 0.01 to 20, preferably 0.01 to 5 parts per 100 resins (considering the whole mixture of the sealing material), pigment particles of a convenient type, size, and concentration, and the powder of the base resin to produce the sealing material; A step of providing the second layer (described above) on the sealing material; A step of laminating the first layer, the second layer, and the sealing material while applying heat and pressure at a temperature of 60 °C to 125 °C, preferably 60 °C to 100 °C, more preferably 70 °C to 90 °C, so as to crosslink the base resin.

[0018] During lamination at a temperature of up to 125 °C, even if the catalyst particles and the base resin particles are discrete, the resin is crosslinked in the same manner as described above. As a result, mechanical properties suitable for use in PV modules - specifically, sufficient rigidity and creep resistance at the expected maximum supply temperature (i.e., about 85 °C, with a safety margin added, up to 105 °C) - are obtained.

[0019] As a result of the processing temperature being lower than normal, the viscosity during lamination becomes higher than normal, and the tangent delta becomes lower than normal. This not only prevents the migration and aggregation of pigment particles but also prevents the excessive inflow of the colored sealing material. As a result, the color scheme of the module becomes uniform. This result is surprising and shows an unexpected synergistic effect between low-temperature processing and the use of pigments to color the module.

[0020] Therefore, this method can be used not only when laminating conventional PV modules in a conventional laminator, but also when laminating PV modules containing temperature-sensitive PV cells, such as perovskite cells or dye-sensitized cells. Also, the energy consumption is reduced by the decrease in the processing temperature during lamination. Again, it should be noted that one of the above-mentioned first layer and second layer may constitute a part of an existing pre-manufactured PV module on which other layers are laminated, or may be an individual layer of the PV module.

[0021] Advantageously, the base resin has a complex viscosity of more than 10000 Pa·s at 85°C and more than 6000 Pa·s at 100°C before lamination.

[0022] Advantageously, the base resin exhibits a tangent delta value of less than 1.0 at 85°C and less than 1.2 at 100°C before lamination.

[0023] Due to the above characteristics, a sealing material with good processability can be obtained.

[0024] Advantageously, the mixture further contains other additives including at least one of an antioxidant, an ultraviolet absorber, and an ultraviolet stabilizer. This other additive may be mixed and / or combined with the base resin simultaneously with the mixing and / or combination with the catalyst, or in a separate step before the resulting mixture is mixed and / or combined with the catalyst.

[0025] Advantageously, the catalyst comprises one or more of boric acid, metallocene catalysts, geometrically constrained catalysts, reversible chain transfer catalysts, such as multi-site catalysts like Ziegler-Natta catalysts or Phillips catalysts. Such crosslinking catalysts may include metal (e.g., cobalt, tin, zinc, iron, lead, etc.) carboxylic acids, dialkyltin mercaptides, tin octoate, dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, tin acetate, tin caprylate, zinc caprylate, organic bases - such as ethylamine, dibutylamine, or hexylamine -, inorganic acids - such as sulfuric acid -, or organic acids - such as toluenesulfonic acid, stearic acid, and maleic acid.

[0026] Advantageously, after the lamination step, the encapsulant exhibits a complex viscosity greater than 15000 Pa·s at 85°C and greater than 10000 Pa·s at 100°C.

[0027] Advantageously, after the lamination step, the encapsulant exhibits a tangent delta value of less than 1.0 (preferably less than 0.8 at 85°C) and less than 1.2 (preferably less than 1.0 at 85°C) at 100°C.

[0028] These properties are sufficient to provide the required structural stability and creep resistance at the supply temperature required immediately after lamination. Further crosslinking after lamination further improves the creep resistance of the encapsulation layer.

[0029] Advantageously, at least a portion of the pigment particles - preferably at least 50% or even more preferably at least 75% - have a diameter that takes a median value in the range of 100 nm to 50 μm - preferably 100 nm to 5 μm, more preferably 300 nm to 700 nm, and even more preferably 400 nm to 600 nm. The diameter of the particles can be optimized for the desired optical properties of the front encapsulation layer. Similarly, the pigment particles may be provided in the front encapsulation layer at a mass concentration of 0.01 to 10 parts per 100 parts of resin. This is repeated, but can be adjusted to optimize the desired properties. Precise particle size and particle concentration can be arrived at by routine experimentation to achieve the desired optical properties (color, reflectance, transmittance, special interference effects, etc.), and it goes without saying that there is no special relationship between the prior art particle size and particle concentration - this relationship depends on the desired optical properties.

[0030] Advantageously, the pigment particles comprise at least one of zinc-based pigments (such as zinc oxide or zinc chromate), titanium-based pigments (such as titanium oxide or titanium yellow), iron-based pigments (such as iron oxide or Prussian blue), chromium-based pigments (such as chromium oxide), bismuth-based pigments (such as bismuth vanadate), cobalt-based pigments (such as cobalt blue) or cobalt tin oxide or cobalt / lithium / titanium oxide), aluminum-based pigments (sodium silicate composite containing sulfur), tin-based pigments (such as tin sulfide) or copper-based pigments.

[0031] Such a photovoltaic module will, of course, be suitable for use in building structures.

Brief Description of the Drawings

[0032] Further details of the present invention will become clearer by reading the following description together with the following figures.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

[0033] Hereinafter, it should be noted that one or more intermediate layers can also exist between the above-mentioned layers unless it is specified that a specific layer is directly provided on an adjacent layer. Therefore, "on" should be taken to mean "directly or indirectly on" unless otherwise specified. Furthermore, the patterning of certain layers, connectors, etc. is not shown because it is well known to those skilled in the art.

[0034] Figure 1 shows a classical configuration of the photovoltaic module 1. The photovoltaic module 1 includes a front sheet 3 provided on the light incident surface of the photovoltaic module 1 and intended to emit light during use, and a back sheet 11 provided on the surface of the module 1 located opposite to the front sheet 3. The front sheet 3 may be glass, transparent ceramics, polymer, or any other convenient and substantially transparent material. The back sheet may be metal, glass, ceramics, polymer, or any other convenient material. The front sheet 3 may be constructed to have a coating. One of the front sheet 3 and the back sheet 11 may represent the "first layer" in the present invention. The layer sealed by this first layer with a sealing layer corresponds to the "second layer" in the present invention. Alternatively, any two specific layers of the configuration of the PV module sealed together may represent the first layer and the second layer in the present invention. Alternatively, either the first layer or the second layer may constitute a part of an existing pre-manufactured PV module with other layers laminated thereon.

[0035] As is widely known, one or more PV cells having NIP, PIN, NP, or PN junctions, patterned, and interconnected, are provided between the front sheet 3 and the back sheet 11. The PV cells may be based on thin-film silicon, crystalline silicon, germanium, perovskite, dye-sensitized cells, or any other type of PV technology adapted to generate electricity from light incident on the light incident surface of the PV module 1 and passing through the photoactive region of the PV conversion device 7. The present invention is particularly applicable to the encapsulation of PV modules incorporating dye-sensitized perovskite cells, but is equally applicable to any PV cell technology.

[0036] The PV conversion device 7 is sealed on the light incident surface by a front sealing layer 5 that seals the light incident surface to the front sheet 3, and on the back surface by a back sealing layer 11. The back sealing layer 11 seals the PV conversion device 15 to the back sheet 19. That being said, the back sealing layer 11 itself may constitute the back sheet. Each of the sealing layers 5, 9 typically has a thickness of from 200 μm to 1 mm. Further, a plurality of front sealing layers 3 may be laminated on top of each other. The front sealing layer 5 and / or the back sealing layer 9 are produced specifically according to the present invention. The front sealing layer 5 and / or the back sealing layer 9 will be described in detail later.

[0037] Note that other intermediate layers may be provided between the plurality of layers shown in the figure, and these layers need not be flat, may have a curvature, or may represent a more complex surface. In such cases, using the powdery sealing material by itself or in combination with its film can be advantageous in ensuring that all details of the shape are filled with the sealant. In particular, using the powdery sealing material to fill a certain area on the base layer to ensure a uniform sealing layer after lamination, the same principle can be applied regardless of the shape of the layer.

[0038] Figure 2 shows another variant of the structure of the PV module 1 produced by laminating the front sheet 3 on an existing pre - manufactured PV module 17 by means of the front seal 5. The other layers 7, 9, 11 are those designed hitherto. As a result, the original front sheet and the front seal of the pre - manufactured module 17 become the inner front sheet 13 and the further sealing layer 15, respectively. The same applies to the back seal 9 and the back sheet 11 as described above. This structure enables the front functional expression of an existing module 17 by a front sheet 3 that is constructed, printed, contains the desired additives, for example, the optical filters disclosed in Patent Documents 7, 9, 10, or exhibits a similar functional expression.

[0039] Figure 3 schematically shows a method for manufacturing the PV module 1 according to the present invention.

[0040] The laminate 31 comprising at least layers 3, 5, 7, 9 is united within the laminating apparatus 33 together with the other existing layers. In the case of the embodiment of FIG. 2, the laminate includes the pre-manufactured PV module 17. On the pre-manufactured PV module 17, the front sealing layer 5 and the front sheet 3 (and any other desired layers) are applied. Note that the laminate 31 can be united within the laminating apparatus 33. At this time, in either a state where the light incident surface of the final PV module faces upward or downward, this orientation determines which specific layer is the "first" and "second" layer in the present invention. Further, one or more of the sealing layers 5, 9 may be applied to the laminate 31 as a film and / or powder.

[0041] The laminating apparatus may be a vacuum bag laminating apparatus, a roller type laminating apparatus, or any other convenient type. The laminating apparatus 33 then applies heat and pressure at a temperature lower than normal. The temperature is applied particularly at 60°C to 125°C, preferably at 60°C to 100°C, more preferably at 70°C to 90°C, and the pressure is applied at a maximum of 2 bar gauge pressure (usually substantially 2 bar gauge pressure) for an appropriate period (for example, 20 minutes to 2000 minutes). Thereby, various sealing layers are fused and crosslinked to form the final PV module 1.

[0042] As a result, the PV module 1 according to the present invention can be made with a conventional PV processing apparatus without the need for a special apparatus. Further, the energy consumption in manufacturing is reduced due to the decrease in the processing temperature.

[0043] In order to enable lamination at a temperature lower than the normal temperature as described above while maintaining the desired mechanical properties of the sealant during lamination and supply, at least one of the sealing layers 5, 9 is specially manufactured as described below.

[0044] The encapsulation layer 5,9 is produced from a silane-modified polyolefin base resin - for example polyethylene or other ethylene polymers or copolymers or mixtures of such polymers. Such base resins contain silane functional groups already bonded to the polymer molecules and are commercially available from, for example, Padanaplast, Dow, Evonik and other companies. Hereinafter, a specific form will be referred to by the manufacturer's reference data which does not vary for the specific form. Thus reproducibility is guaranteed to those skilled in the art.

[0045] Such base resins can typically be obtained by treating one or more polyolefins (for example polyethylene, polypropylene, or a copolymer of ethylene or propylene with another monomer selected from C 3 -C 10 alkenes) in the presence of a compound containing a hydrolyzable silane group. Other examples of polyolefins are allylcyclohexane, vinylcyclohexane, norbornene, polystyrene, acrylic polymers, acrylate polymers, methacrylates - such as PMMA - and the like. Further examples of polyolefins can be found in ASM D883-12 or Ullmann's Encyclopedia of Industrial Chemistry. The treatment of the base resin may be carried out, for example, by melt-treating one or more polyolefins in the presence of a compound containing a hydrolyzable silane group and a compound capable of generating free radicals. However, since such base resins are available as off-the-shelf products from multiple manufacturers, those skilled in the art do not need to synthesize them themselves but only need to select a suitable base resin. The base resin in question ideally has the following properties before lamination. The base resin in question ideally has the following properties before lamination.

Table 1

[0046] For reference, complex viscosity is a frequency-dependent viscosity function determined during forced harmonic oscillation of shear stress and is defined as the complex modulus divided by the angular frequency. Here, the complex modulus represents the overall resistance to deformation of the material, whether the deformation is recoverable (i.e., elastic) or non-recoverable (i.e., viscous). This is measured by a dynamic moving rheometer or similar device at a frequency of 1 Hz and a strain of 10% in the present application. Tangent delta - also known as "loss tangent" - is the phase angle given by the ratio of the loss modulus (G'') to the storage modulus (G') and represents the presence and magnitude of elasticity in a fluid. Again, at a frequency of 1 Hz and a strain of 10%, a tangent delta less than 1.0 suggests elastic-dominated (i.e., solid-like) behavior, while a value greater than 1 suggests viscous-dominated (i.e., liquid-like) behavior.

[0047] The cited density ranges represent the optimum in terms of the crystallinity and melting point of the base resin. The melting point range ensures that the encapsulant can melt at low lamination temperatures. The viscosity value and the tangent delta value are important values that reflect the processability of the encapsulant under standard lamination conditions. Examples of specific commercially available resins with these properties are given in the following examples, but those skilled in the art know how to select others based on the properties given by examining appropriate material data sheets. Essentially, polymers having the above-described properties are laminatable at the required temperature, while those having parameters outside these ranges have typically been shown to be unsuitable.

[0048] The base resin is combined with a crosslinking catalyst at a concentration of 0.01 phr to 5 phr, or even up to 20 phr. This catalyst may include boric acid as a water source, metallocene catalysts, geometrically constrained catalysts, reversible chain transfer catalysts such as Ziegler-Natta catalysts or Phillips catalysts or silanes, and other optional types of multi-site catalysts suitable for catalyzing the crosslinking of polyolefin molecules by water. The water may be water in the environment and / or may be provided by, for example, boric acid or a similar compound that decomposes to release water when heated. The catalyst may be provided as a powder or solution, or may already be incorporated with the polymer in a catalyst masterbatch. Other examples of such catalysts are metal (such as cobalt, tin, zinc, iron, lead, etc.) carboxylic acids, dialkyltin mercaptides, tin octoate, dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, tin acetate, tin caprylate, zinc caprylate, organic bases such as ethylamine, dibutylamine, or hexylamine, inorganic acids such as sulfuric acid, or organic acids such as toluenesulfonic acid, stearic acid, and maleic acid.

[0049] Hereinafter, the preparation of such catalysts will be referred to again by the manufacturer's reference data that does not change for specific forms. Thus, reproducibility is guaranteed to those skilled in the art.

[0050] Other additives - for example, antioxidants, UV absorbers, and / or UV stabilizers may be added to the encapsulant base resin at a concentration of, for example, 0.1% to 5%. Further, the encapsulant may also contain pigment particles as additional additives. Such particles may be present, for example, at a concentration of 0.01 to 10 phr or wt%, preferably 0.1 to 5 phr or wt%, more preferably 0.1 to 1 phr or wt%, and may have a size in the range of 100 nm to 1 μm, more notably 300 nm to 700 nm, and most notably 400 nm to 600 nm. Preferably at least 50%, more preferably at least 75%, and even more preferably substantially all of the pigment particles have a set size. It should be noted that the pigment particles are discrete particles that are clearly different from the colorant dispersed at the molecular level within the encapsulant or the encapsulant made from a pre-colored material. As an example of a suitable pigment, titanium oxide or zinc oxide particles may be used to produce white. Yellow, orange, red, and brown may be produced using iron oxides - Fe 2 O 3 for red-brown or FeO(OH) - for yellow. Blue may be produced, for example, by a sulfur-containing sodium silicate complex or Prussian blue. Such pigment particles 21 absorb a portion of the visible light incident on the PV device 1 to produce the desired color and diffuse the light that masks various features of the PV conversion device 15. The various features are, for example, the patterning of the PV conversion device 15, the electrical interconnections between individual cells, the edges of individual cells, the color shift between individual cells and the back encapsulant 17 and / or the backsheet 19, etc.

[0051] More detailed examples of specific off-the-shelf dyes that have been tried and succeeded are as follows.· Red: Red iron oxide dyes - for example, Rot110M of Scholz Farbpigmente Schweiz in Switzerland, Sicocer® F Coral2320 of BASF. Typical dosages are 0.05 - 2 phr.· White: Dupont Ti-Pure R-900, R-960 of DuPont. Typical dosages are 0.1 - 1 phr.· Yellow: Nubifer Y-4000 of Ferro. Typical dosages are 0.1 - 2 phr.· Green: PG17 S series of Ferro, Sicopal® GREEN K 9610 or 9710 of BASF. Typical dosages are 0.05 - 2 phr.

[0052] Of course, it also points out other commercially available off-the-shelf dye particles. Such dye particles include zinc-based dyes (such as zinc oxide or zinc chromate), titanium-based dyes (such as titanium oxide or titanium yellow), iron-based dyes (such as iron oxide or Prussian blue), chromium-based dyes (such as chromium oxide), bismuth-based dyes (such as bismuth vanadate), cobalt-based dyes (such as cobalt blue) or cobalt tin oxide or cobalt / lithium / titanium oxide), aluminum-based dyes (sodium silicate composite containing sulfur), tin-based dyes (such as tin sulfide) or copper-based dyes.

[0053] The dye particles 21 absorb a part of the visible light incident on the PV device 1 so as to generate a desired color, and diffuse the light that provides a uniform color and hides various features of the PV conversion device 15. The various features are, for example, the patterning of the PV conversion device 15, the electrical interconnection between individual cells, the ends of individual cells, and the color deviation between individual cells and the back seal 17 and / or the back sheet 19.

[0054] This scattering effect is particularly advantageous over simply providing a front encapsulant colored by a colorant dispersed internally at the molecular level. This is because such colorants hide the various features of the PV conversion element 7 described above by greatly increasing the light transparency due to the absence of light scattering.

[0055] Furthermore, the scattering effect facilitates the diffusion of light passing through the front encapsulant 5 and entering the photo - electrically active part of the PV conversion element 7 in a manner similar to that of a conventional diffusion element contained within the PV module 1 on the light - incident surface of the PV conversion element 7, thereby increasing the average optical path length of the light passing through the cell. Naturally, the overall efficiency decreases in proportion to the light that is reflected, i.e., scattered backward, towards the light - incident surface of the PV device.

[0056] The size of the dye particles 21 can be adjusted to increase the transmittance within the infrared range of the PV conversion element 5 sensitive to IR light. By optimizing the size and density of the dye particles within the front encapsulation layer 5, interference can occur between the dye particles 21 that gives a glow, a faint light, or an iridescent effect. More specifically, the size and concentration of the dye particles, the front encapsulation layer, etc. can be adjusted by ordinary experiments within the above - mentioned ranges to achieve the desired color, optical effect, transmittance, reflectance, etc.

[0057] The mixture of the base resin, the pigment particles, and the catalyst (along with any other additives) is combined to produce a film of the sealing material or any other convenient form (such as a cylinder) that is later milled into a powder. Then, at a temperature of 90°C to 190°C, preferably at a temperature of 140°C to 180°C, preferably at a temperature of 160°C to 180°C, preferably at a temperature of 160°C to 180°C, preferably at a temperature of 165°C to 180°C, it can be extruded, for example, by a twin-screw extruder or other forms of extruders. This is schematically represented in Figure 4. In the figure, the base resin and the catalyst preparation (including catalyst powder, solution, or catalyst masterbatch containing a catalyst already combined with the polymer) are mixed, combined, and extruded. Figure 5 schematically represents another variant of this process. In the figure, the base resin is mixed and combined with other additives - such as ultraviolet absorbers, ultraviolet stabilizers, and / or antioxidants - and then extruded. The resulting mixture is subsequently mixed and combined with the catalyst preparation (described above) and extruded.

[0058] By means of a conventional extrusion process, it is ensured that the time the melt remains in the extruder before solidifying is relatively short, making the cross-linking of the polymer relatively unlikely to occur. However, some cross-linking will occur but it will not be a problem. Even if excessive cross-linking occurs in the extruder, those skilled in the art can easily solve such problems by modifying the extrusion parameters (temperature, extrusion pressure, extrusion flow rate, etc.) through normal experiments. Thus, the sheet and / or powder can be provided in the laminate 31 within the laminating device 33 as described above. By applying heat and pressure, the silane cross-links the polymer molecules in the presence of water (which may be derived from, for example, boric acid or other components of the catalyst) at the lamination temperature to cure the sealing material and bond it to the adjacent layer.

[0059] In other variants, any additives other than the base resin and the catalyst are combined at the above temperature, extruded into a shape such as a cylinder or a strand, and then milled to form a powder. As schematically represented in FIG. 6, this base resin powder may subsequently be mixed with a crosslinking material powder or liquid (either itself or already combined with a polymer) containing a crosslinking agent (i.e., a catalyst) material, pigment particles, and optionally further additives - antioxidants, UV absorbers, and / or UV stabilizers. This powder may have a particle size of 1 to 1000 μm, preferably 1 to 100 μm. The resulting powder mixture constitutes the encapsulant of the present invention. In a further variant of this process, schematically represented in FIG. 7, the base resin (which may be in powder, pellet, or any other convenient form) and the above-mentioned further additives are first mixed, combined, and extruded. The resulting mixture is then milled to form a powder. This latter powder is subsequently mixed with the above-mentioned crosslinking agent in powder or liquid form (which may or may not contain a polymer component) to form the encapsulation material powder.

[0060] This powder mixture is subsequently provided within the above-described laminate 31 and heated at 60° C. to 125° C., preferably 60° C. to 100° C., more preferably 70° C. to 90° C., and a pressure of 0.5 to 2 bar gauge pressure is applied so that when these components soften and bond, the catalyst interacts with the base resin. Thereby, the polymer of the base resin is crosslinked in the same manner as when the catalyst is mixed with the base resin before extrusion.

[0061] After lamination, the resulting encapsulant has the following modified properties. These modified properties provide the desired strength and creep resistance at the time of provision.

Table 2

[0062] As a result, the rheological behavior of the encapsulant during the overall process is controlled. As a result, migration of the dye particles and excess material in the laminate is prevented. Aggregation of the dye particles and significant flow of the encapsulant are avoided. As a result, the color scheme of the module becomes uniform. The reason for this is that the viscosity of the encapsulant remains high throughout the process (with a complex viscosity of ≧4000 Pa·s, and the tangent delta value of the encapsulant being less than 1.2, preferably less than 1.0), thereby preventing migration of these dye particles especially during the initial stage of the laminate where heat is applied. During this stage of a conventional laminate, the viscosity value typically becomes relatively low before the time when the encapsulant should cure. This has allowed migration and aggregation of the dye, which causes significant thickness variation in the encapsulation layer, and flow of the excess material. Such a synergistic effect between low-temperature lamination in particular and avoidance of dye migration and flow of excess material gives an unexpected technical effect, enabling a very uniform color scheme of the module.

[0063] A number of test results without dyes are reproduced below. The following test results give specific examples of specific combinations of materials where the method of the present invention achieves the desired results of good low-temperature lamination and also achieves the desired mechanical specifications and rheological properties of the encapsulation layer.

[0064] "Example 1"

Table 3

[0065] Table 3 describes the details of the form of this example. In the table, "phr" relates to parts per 100 resins. The antioxidant and the UV stabilizer were first compounded into an additive masterbatch by a twin-screw extruder at 170°C. Subsequently, a mixture of the base resin, the catalyst masterbatch, and the additive masterbatch was extruded by a single-screw extruder at 170°C into a film with a thickness of 0.5 mm. The extruded film was subsequently tested in a series of evaluation steps.

[0066] The film was first laminated between two glass plates, each with a thickness of 3 mm, in a standard flat trapezoidal vacuum bag lamination apparatus at 65 °C with a total cycle time of 60 minutes. The resulting laminate had no bubbles or other visual defects. The post-lamination peel strength between the foil and the glass was measured to exceed 10 N / mm by a standard 90° peel test performed by a standard tensile testing apparatus. Subsequently, the laminated glass plates were subjected to a standard creep test at 85 °C and 85% relative humidity. As a result, it was shown that no creep occurred under the weight of the glass even after 100 hours. This is equivalent to a laminate of 15 kg / m 2 of the laminate.

[0067] "Example 2"

Table 4

[0068] Table 4 describes the details of the form of this example. The antioxidant, ultraviolet absorber, and ultraviolet stabilizer were first formulated into an additive masterbatch by a twin-screw extruder at 170 °C. Subsequently, a mixture of the base resin (including a 50:50 mixture of two different resins shown in the table), the catalyst masterbatch, and the additive masterbatch was extruded by a single-screw extruder at 170 °C into a film with a thickness of 0.5 mm. The subsequently extruded film was tested in a series of evaluation steps.

[0069] The film was first laminated between two glass plates, each with a thickness of 3 mm, in a standard flat trapezoidal vacuum bag lamination apparatus at 85 °C with a total cycle time of 60 minutes. The resulting laminate had no bubbles or other visual defects. The post-lamination peel strength between the foil and the glass was measured to exceed 5 N / mm by the above-mentioned standard 90° peel test. Subsequently, the laminated glass plates were subjected to a standard creep test at 85 °C and 85% relative humidity. As a result, it was shown that no creep occurred even after 100 hours. "Example 3"

Table 5

[0070] Table 5 describes the details of this example form. The antioxidant, the ultraviolet absorber, and the ultraviolet stabilizer were first compounded into an additive masterbatch by a twin-screw extruder at 170°C. Subsequently, a mixture of the base resin, the catalyst masterbatch, and the additive masterbatch was extruded by a single-screw extruder at 170°C to form a film with a thickness of 0.5 mm. Subsequently, the extruded film was tested in a series of evaluation steps.

[0071] The film was first laminated between two glass plates each with a thickness of 3 mm in a standard flat trapezoidal vacuum bag laminating device at 85°C and a total cycle time of 60 minutes. There were no bubbles or other visual defects in the resulting laminate. The peel strength between the foil and the glass after lamination was measured to exceed 5 N / mm by the above-mentioned standard 90° peel test. Subsequently, the laminated glass plates were subjected to a standard creep test at 85°C and a relative humidity of 85%. As a result, it was shown that no creep occurred even after 100 hours.

[0072] "Example 4"

Table 6

[0073] Table 6 describes the details of this example form. The antioxidant and the ultraviolet stabilizer were first compounded into an additive masterbatch by a twin-screw extruder at 190°C. Subsequently, a mixture of the base resin, the catalyst masterbatch, and the additive masterbatch was extruded by a single-screw extruder at 170°C to form a film with a thickness of 0.5 mm. Subsequently, the extruded film was tested in a series of evaluation steps.

[0074] The foil film was first laminated between two glass plates, each with a thickness of 3 mm, in a standard flat trapezoidal vacuum bag laminating device at 85 °C with a total cycle time of 60 minutes. The resulting laminate had no bubbles or other visual defects. The peel strength between the foil and the glass after lamination was measured to exceed 10 N / mm by the above-mentioned standard 90° peel test. Subsequently, the laminated glass plates were subjected to a standard creep test at 85 °C and 85% relative humidity. As a result, it was shown that no creep occurred even after 100 hours.

[0075] As shown by the above results, the encapsulant material produced by the method of the present invention can be laminated at a significantly lower temperature than conventional materials, while maintaining the peel strength and creep resistance at 85 °C. As a result, conventional lamination devices and methods can be used to laminate PV modules containing temperature-sensitive PV cells - for example, those based on perovskite technology or dye-sensitized technology - into one.

[0076] Regarding the use of dyes, the presence of the dye did not affect the mechanical properties of the resulting module. Furthermore, during annealing, the colored encapsulant did not decolorize or change its properties. As a result, it can be concluded that no specific cross-degradation mechanism occurred between the dye and the encapsulant used.

[0077] The results of the chemical stability and UV stability tests of various samples produced by the present invention are reported in Figures 8 to 10 as follows.

[0078] Figure 8 represents a graph of reflectance and transmittance against wavelength at various equivalent exposure times in a standard QSun exposure chamber. In the graph, the module was constructed according to Figure 1, with 1 phr of TiO 2A 0.8 mm thick polyolefin type front seal 21 (Polidiemme FE1252 EXP) containing a pigment (Dupont's Ti-Pure R-960, median particle size: 0.5 μm) was used. The front sheet was a 2 mm thick glass plate. As can be seen from the figure, there was no change in reflectivity or transmittance at any wavelength of light equivalent to up to 6423 hours of sunlight exposure. The change was simply within the range of measurement variation.

[0079] The perceived color change was also measured according to the CIE (1994) standard.

Table 7

[0080] As can be seen from the figure, the value of ΔE CIE94 is very low and remains substantially constant (within the range of measurement variation) over a long exposure time. In a practical sense, no color change was observed.

[0081] Figure 9 shows the sample of Figure 8 that has been subjected to 1000 hours of damp heat exposure according to IEC61215 at 85 °C and 85% relative humidity. Again, hardly any difference in transmittance and reflectivity was observed at any wavelength, and a ΔE CIE94 value of 0.62 was obtained at 1000 hours. Again, in a practical sense, no color change was observed.

[0082] Figure 10 shows a red-colored sample similar to that used to generate the data of Figure 8. However, the pigment was iron oxide with a concentration of 0.1 phr (Scholz Farbpigmente's Rot110M with a median particle size of 0.5 μm), which gave the same results as before. The value of ΔE CIE94 was as follows.

Table 8

[0083] Therefore, although it is repetitive, in a practical sense, no color change was observed.

[0084] Finally, FIG. 11 shows the photovoltaic module 1 according to the invention placed on the ceiling of the building structure 35. Alternatively, the PV module 1 may be placed on the outer wall or, instead, may be integrated into the wall and / or ceiling structure - for example, as a cladding. In a general sense, the PV module 1 may be placed on or inside the building structure 35.

[0085] Although the invention has been described in specific embodiments, variations of the invention are possible without departing from the technical scope of the invention as defined in the "claims".

Claims

1. 1. A method for manufacturing a photovoltaic module comprising at least a first layer and a second layer secured together by an encapsulant, comprising: Providing a lamination device; providing the first layer in the lamination apparatus; providing an encapsulant on the first layer by providing a base resin having a melting point below 90°C comprising a silane modified polyolefin; forming a mixture of said base resin, pigment particles and an additive comprising a crosslinking catalyst present in a ratio of 0.01 to 20 parts per 100 parts of resin; melting said mixture at a temperature of 90°C to 190°C; and extruding said mixture to form an encapsulant; providing the second layer over the encapsulant; laminating the first layer, the second layer, and the encapsulant under heat and pressure applied at a temperature of 60° C. to 125° C. to crosslink the base resin; The base resin has a complex viscosity of greater than 10,000 Pa·s at 85° C. and greater than 6,000 Pa·s at 100° C. before lamination; said base resin exhibiting a tan delta value at 85°C less than 1.0 and at 100°C less than 1.2 prior to lamination; After the lamination step, the encapsulant exhibits a complex viscosity at 85° C. of greater than 15,000 Pa·s and at 100° C. of greater than 10,000 Pa·s; After the lamination step, the encapsulant exhibits a tan delta value of less than 1.0 at 85° C. and less than 1.2 at 100° C. method.

2. The method of claim 1 , wherein the encapsulant is extruded as a sheet.

3. The method of claim 1 , wherein the encapsulant is extruded and subsequently ground into a powder before being disposed over the first layer.

4. 1. A method for manufacturing a photovoltaic module comprising at least a first layer and a second layer secured together by an encapsulant, comprising: Providing a lamination device; providing the first layer in the lamination apparatus; providing an encapsulant in powder form on the first layer, the encapsulant being realized by providing a base resin in powder form, the base resin having a melting point of less than 90° C., the base resin comprising a silane-modified polyolefin; and mixing an additive comprising a crosslinking catalyst present in the encapsulant in a ratio of 0.01 to 5 parts per 100 parts of resin, pigment particles, and the powder of the base resin to form a mixture to form the encapsulant; providing the second layer over the encapsulant; laminating the first layer, the second layer, and the encapsulant under heat and pressure at a temperature of 60° C. to 125° C. to crosslink the base resin; The base resin has a complex viscosity of greater than 10,000 Pa·s at 85° C. and greater than 6,000 Pa·s at 100° C. before lamination; said base resin exhibiting a tan delta value at 85°C less than 1.0 and at 100°C less than 1.2 prior to lamination; After the lamination step, the encapsulant exhibits a complex viscosity at 85° C. of greater than 15,000 Pa·s and at 100° C. of greater than 10,000 Pa·s; After the lamination step, the encapsulant exhibits a tan delta value of less than 1.0 at 85° C. and less than 1.2 at 100° C. method.

5. 5. The method of claim 1, wherein the mixture further comprises other additives including at least one of an antioxidant, an ultraviolet absorber, and an ultraviolet stabilizer.

6. 6. The method of claim 5, wherein the catalyst comprises one or more of boric acid, a metallocene catalyst, a constrained geometry catalyst, a chain shuttling catalyst, a multi-site catalyst such as a Ziegler-Natta catalyst or a Phillips catalyst.

7. The method of claim 6 , wherein at least a portion of the pigment particles have a diameter in the range of 100 nm to 50 μm.

8. The method of claim 7 , wherein the pigment particles are provided in the encapsulant at a weight concentration ranging from 0.01 to 10 parts per 100 parts of resin.

9. 9. The method of claim 8, wherein the pigment particles comprise at least one of a zinc-based pigment, a titanium-based pigment, an iron-based pigment, a chromium-based pigment, a bismuth-based pigment, a cobalt-based pigment, an aluminum-based pigment, a tin-based pigment, and a copper-based pigment.

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