FR3084524A1 - PROCESS FOR PRODUCING A FLEXIBLE LAMINATE OF PHOTOVOLTAIC CELLS - Google Patents

Abstract

The present invention relates to a method for manufacturing a flexible laminate (1) of photovoltaic cells (3) in which - a layer of photovoltaic cells (3) connected to each other and front (5) and rear ( 7) for encapsulating the layer of photovoltaic cells (3), (101) - a decorative film (9) is deposited on the front encapsulation layer (5), (102) - a protective layer is deposited (11 ) on the decorative film (9) (103).

Description

Method for manufacturing a flexible laminate of photovoltaic cells

The present invention relates to the field of photovoltaic panels. More particularly, the present invention relates to laminated photovoltaic panels. These photovoltaic panels are of the flexible or flexible type, that is to say that they can be deformed so that they do not crack when they are applied a curvature with a radius of curvature of 1 meter.

With the advent of renewable energies and in particular solar energy, research in the field of photovoltaic panels composed of one or more photovoltaic cells is booming and in particular to increase the conversion yields, and therefore l energy produced from such photovoltaic panels, as well as to reduce the operating and maintenance costs of these photovoltaic panels.

To date, we want to better exploit the surfaces of existing industrial or commercial buildings, in particular by installing photovoltaic panels on their facades or roofs. In fact, for the building operator, the generation of electrical energy can generate additional income or savings and help to promote the economic operation of the building.

However, these commercial or industrial buildings are often constructed with, for example, a metal or wooden frame which is sized to meet just the technical constraints in terms of load to support the roof with insulation as well as a snow load for example depending of the construction area.

Thus, due to their weight, it is currently not possible to install certain photovoltaic panels on the roof of certain buildings so as not to contravene the technical standards in force. Indeed, most known photovoltaic panels generally have a glass front face and a metal support frame so that a single photovoltaic panel often weighs more than 20 kg, or even 30 kg for certain models.

Furthermore, the state-of-the-art photovoltaic panels generally have a black color which can limit or prevent their development in areas where town planning rules impose certain aesthetic constraints to prevent constructions from degrading the landscape or the landscape too much. uniformity of existing constructions.

Thus, we are deprived of equipping photovoltaic panels with large areas available today, in particular old buildings due to their limited dimensioning in terms of load or town planning rules preventing the introduction of large black areas on buildings .

The object of the present invention is to at least partially remedy the various drawbacks of the prior art set out above in particular by proposing a manufacturing process making it possible to obtain laminate of colored photovoltaic cells whose weight is reduced in order to increase the number of locations in which photovoltaic panels can be installed.

In order to achieve at least partially at least one of the aforementioned objectives, the present invention relates to a method of manufacturing a flexible laminate of photovoltaic cells in which a layer of photovoltaic cells connected to each other and front layers is assembled by lamination. and rear of encapsulation of the layer of photovoltaic cells, a decorative film is deposited on the front encapsulation layer, a protective layer is deposited on the decorative film.

According to another aspect of the present invention, the deposition of the decorative film is carried out by a vapor deposition process.

According to an additional aspect of the present invention, the decorative film comprises an interferometric filter.

According to a further aspect of the present invention, the decorative film is a film comprising a colored pattern.

According to another aspect of the present invention, the photovoltaic cells are silicon-based cells.

According to an additional aspect of the present invention, the protective layer is a transparent varnish.

According to an additional aspect of the present invention, the varnish is produced from a polymer-based material chosen from polyurethane varnishes, acrylic type varnishes, polyester type varnishes, silicone type varnishes, or even type varnishes epoxy ..

According to another aspect of the present invention, the varnish has anti-fouling properties such as a water repellency or anti-reflection properties or anti-scratch properties.

According to a further aspect of the present invention, the protective layer is a flexible transparent film forming an additional layer bonded to the decorative film by an adhesive.

According to an additional aspect of the present invention, the adhesive is made of the same material as the encapsulation layers and comprises ethylene vinyl acetate "EVA".

According to another aspect of the present invention, the additional layer has anti-fouling properties, in particular a predetermined roughness and / or a water-repellent character or anti-reflective properties or anti-scratch properties.

According to a further aspect of the present invention, the lamination assembly also includes a rear connection layer disposed behind the rear encapsulation layer.

Other characteristics and advantages of the present invention will appear more clearly on reading the following description, given by way of illustration and not limitation, and the appended drawings in which:

• Figure 1 is a schematic top view of a photovoltaic panel, • Figure 2 is a schematic cross-sectional and exploded view of a laminate of photovoltaic cells according to a first embodiment, • Figure 3 is a view schematic in cross-section and exploded view of a laminate of photovoltaic cells according to a second embodiment, • Figure 4 is a flow diagram of the steps of a manufacturing process according to the present invention.

In these figures, identical elements have the same numerical references.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments.

In the following description, the term "front layer" means the surface of the flexible laminate exposed first to the sun's rays in the installed state of the flexible laminate. Likewise, the term “rear layer” is understood in the following description to mean the layer opposite to the front layer, that is to say the surface which is last impacted by the sun's rays during their passage through the laminate to the installed state of the laminate.

Then, by “transparent” in the following description is meant a material, through which light can pass with a transmittance of at least 80%, in particular in the wavelengths between 315 nm and 1200 nm.

In addition, in the following description, the term “film or laminate of flexible or flexible material” means the fact that when a certain radius of curvature is applied, the film does not crack. In the present invention the material should withstand without damage a radius of curvature of 1 meter.

On the other hand, with reference to Figures 2 and 3, the different layers making up a flexible laminate 1 are spaced from each other. This representation is only made to better identify the different layers. As the flexible laminate 1 is delivered, the different layers shown are in contact with one another.

Referring to Figures 1, 2 and 3, there is shown a flexible laminate 1 of photovoltaic cells 3 to form for example a panel or a photovoltaic module. The flexible laminate 1 comprises a layer of photovoltaic cells 3, composed according to this particular representation by four strips of photovoltaic cells 3, connected together, a front layer 5 and a rear layer 7 of encapsulation of the layer of photovoltaic cells 3, a decorative film 9 located on the front encapsulation layer face and a protective layer 11, also called front layer, located on the decorative film 9. The laminate 1 may also include a rear connection layer 13 disposed on the rear layer encapsulation 7 and configured in particular to produce the electrical connections between the various photovoltaic cells 3. The rear layer 13 may also include reflective properties for returning the solar rays to the layer of photovoltaic cells 3. Alternatively, the electrical connections between the photovoltaic cells 3 can be performed without neck rear che 13.

The flexibility of the laminate 1 is obtained thanks to the materials constituting the different layers composing this laminate 1 as is explained in more detail later. The use of a flexible laminate 1 for such a photovoltaic panel or module makes it possible to facilitate its transport and its installation because the fragility of the latter is reduced. In addition, the front layer is generally made of a polymer material which may comprise an additive but devoid of glass fibers, which makes it possible to reduce the total weight of the panel.

At least the front encapsulation layer 5, the decorative film 9 and the protective layer 11 are transparent to allow the sun's rays to reach the layer of photovoltaic cells 3 in order to allow their conversion into electrical energy via the photovoltaic effect.

The manufacturing process for this flexible laminate 1 comprises different stages associated with different techniques which will be described from the flow diagram of FIG. 4 and with reference to FIGS. 2 and 3.

The first step 101 relates to the assembly of the layer of photovoltaic cells 3, of the front 5 and rear 7 encapsulation layers and possibly of the rear connection layer 13. This assembly is for example obtained by a conventional lamination process, that is to say by raising the temperature, under vacuum or under an inert atmosphere for example, from a stack of the different layers forming the laminate 1 and then by pressure. on this stack for a determined period.

The front 5 and rear 7 encapsulation layers may for example each comprise a glass fiber fabric 51, 71 and an encapsulation resin 53, 73.

More particularly, the encapsulation resin 53, 73 is disposed between the layer of photovoltaic cells 3 and the glass fiber fabric 51, 71 in order to ensure cohesion between the glass fiber fabric 51, 71 and the layer of photovoltaic cells 3.

Alternatively, each of the two front 5 and rear 7 layers may be formed from a single layer of fiberglass fabric impregnated with encapsulating resin.

The encapsulation resin is for example made of ethylene vinyl acetate "EVA".

The second step 102 relates to the deposition of the decorative film 9 on the front encapsulation layer. The decorative film 9 corresponds for example to a colored film which may have a particular pattern, for example a logo or reproduce a design. The decorative film 9 can choose the final appearance of the laminate, for example to match the tint of the photovoltaic module with the tint of the facade on which it is arranged to reduce its visual impact or, on the contrary, to provide a pattern making it possible to highlight value the photovoltaic module by means of a drawing or a color inscription. The decorative film 9 is for example deposited by physical vapor deposition or by chemical vapor deposition in particular from a plasma. The deposition can also be done by soaking (“dip coating” in English), by centrifugal coating (“spin coating” in English) or by spraying.

The decorative film corresponds for example to a Kromatix® type film which includes a multi-layer interferometric filter making it possible to filter certain wavelengths of visible light to give a colored appearance while allowing high transmittance in the length range d important wave for photovoltaic cells (315-1200nm). Indeed, the interferometric filter makes it possible to return or reflect only a very small portion of the visible spectrum (corresponding to the color desired for the photovoltaic panel), the rest of the spectrum being transmitted to the photovoltaic cells. Such a film is for example described in patent application EP2897795.

The third step 103 relates to the deposition of the protective layer 11 on the decorative film 9. The protective layer 11 makes it possible to protect the other layers of the laminate 1 and in particular the decorative film 9 which allows the photovoltaic module to keep its appearance even when the protective layer 11 is damaged superficially.

According to a first embodiment shown in Figure 2, the protective layer 11 is a transparent varnish. The varnish can be produced in a polymer-based material chosen from polyurethane type varnishes, acrylic type varnishes, polyester type varnishes, silicone type varnishes, or even epoxy type varnishes.

The varnish can allow an anti-reflection, anti-soiling or anti-scratch treatment.

The varnish can also comprise at least one self-extinguishing additive and / or at least one additive making it possible to improve the light scattering and / or at least one additive making it possible to convert photons from certain spectral ranges to the spectral ranges of interest.

The varnish is for example deposited by spraying, by dipping, by chemical vapor deposition (CVP) or applied by roller.

According to a second embodiment shown in FIG. 3, the protective layer 11 is a flexible transparent film comprising at least one additional layer 17 and an adhesive 15 placed on the decorative film 9, for example by an adhesive of the ethylene-acetate type. vinyl (EVA) which can be the same material as the material used for the front and rear encapsulation layers 5 and 7. Alternatively, the protective layer 11 can be applied by liquid, with solidification thereafter.

The, at least one, additional layer 17 comprises for example an anti-reflective, anti-scratch or anti-fouling treatment. The anti-fouling treatment corresponds for example to a predetermined roughness and / or a water-repellent nature making it possible to prevent the adhesion of soiling to the surface of the additional layer 17. The additional layer or layers 17 is for example made of flexible polymer, in particular in the family of polyvinylidene fluorides (PVDF), polyvinyl fluorides (PVF), ethylene tetrafluoroethylene (ETFE), or polyethylene terephthalates (PET), polyurethane, acrylics, or silicones. Two additional layers 17 can for example be superimposed on each other. The additional anti-fouling layer 17 is then placed outside.

When the flexible laminate 1 is installed, the sun's rays first penetrate the protective layer 11, then the decorative film 9, then the front encapsulation layer 5, then the layer of photovoltaic cells 3 and finally, if they do not the back encapsulation layer 7 is not absorbed.

Thus, the protective layer 11 and in particular the additional layer 17 is highly exposed to dust and climatic hazards which can clog it up due to its arrangement. Indeed, soiling can be deposited on this additional layer 17 and cause absorption or scattering phenomena of light which can reduce the production of electrical energy from the photovoltaic panel.

In order to avoid this fouling, the additional layer 17 is made of flexible material with anti-fouling and transparent properties. More particularly, the additional layer 17 of flexible material may have an average roughness of less than 1 μm, in particular between 0.1 and 0.5 μm.

Mean roughness here is understood to mean the roughness generally indicated under the symbol Ra, which corresponds to the arithmetic mean of all the ordinates of the additional layer 17 within a base length. Indeed, such an average roughness for this additional layer 17 makes it possible to limit the adhesion of dust and sandy residues which can for example be contained in rainwater in order to limit and prevent the deposition of dirt and possibly the formation mold on the flexible laminate 1.

Indeed, the lower the roughness, the less the dirt can be anchored on this additional layer 17 because their possibility of adhesion on this additional layer 17 is greatly reduced.

Thus, such an additional layer 17 makes it possible to space the cleaning and maintenance operations to be carried out on this flexible laminate 1, and therefore the costs generated by such operations.

Furthermore, in order to minimize the possibilities of adhesion of dirt on the laminate 1, the additional layer 17 may have a maximum roughness of less than 3 μm, and in particular between 0.1 and 2.6 μm. The term “maximum roughness” is understood here to mean the roughness generally indicated under the symbol Rz which corresponds to the sum of the greatest of the heights of the profile and the greatest of the depths of the trough of the additional layer 17 within a length of base averaged over the total number of base lengths. Indeed, the maximum roughness for this additional layer 17 is also a parameter to take into account, because if the flexible laminate 1 has in certain places points of high roughness, dirt can accumulate around these points and adversely affect the yield. conversion of the photovoltaic panel in which the laminate 1 is integrated.

The "transparency" of the additional layer 17 is not only obtained by its absorption capacities, but also by its thinness. The protective layer 11 of flexible material can have a thickness e of between 20 μm and 500 μm.

In addition, the use of fluoropolymers makes it possible to increase the resistance of the flexible laminate 1, and in particular that of the additional layer 17, to humidity or even to acid attack. In addition, when the polymer forming the additional layer 17 of flexible material is chosen from polyethylene terephthalates (PET), this additional layer 17 is in the form of a three-layer film of which at least one layer is composed of polyethylene terephthalate. The use of such a polymer also makes it possible to confer on the additional layer 17 properties of resistance to humidity or to acid attack in particular. Thus, the maintenance and operating costs of this flexible laminate 1 are limited.

Such materials have average and maximum roughness characteristics compatible with the values necessary to limit the fouling of the flexible laminate 1. In addition, such materials are dielectric materials. Thus, their attraction of dust for example by electrostatic effect is greatly reduced, which also makes it possible to limit the fouling of the flexible laminate 1. Furthermore, the use of such materials allows the additional layer 17 of flexible material to present anti-reflective properties so as to optimize the photovoltaic conversion yields of the flexible laminate 1.

The photovoltaic cells 3 forming the layer of photovoltaic cells 3 in this flexible laminate 1 are for example cells based on monocrystalline or polycrystalline silicon. The use of monocrystalline silicon provides good yields of photo voltaic conversion per square meter. Furthermore, such a material also has good resistance to aging, which makes it possible to increase the longevity of this flexible laminate 1.

Furthermore, the front 5 and rear 7 encapsulation layers may each have a thickness E of between 0.05 mm and 3 mm. Such a thickness E of the front 5 and rear 7 encapsulation layers makes it possible to obtain a flexible laminate 1 of small thickness, which in particular makes it possible to reduce the costs associated with its transport and its weight. According to the particular embodiments shown here, the front 5 and rear 7 encapsulation layers have the same thickness E. However, according to a variant not shown here, these front 5 and rear 7 encapsulation layers may have different thicknesses.

The exemplary embodiments developed here are examples provided by way of illustration and not limitation. Indeed, it is entirely possible for a person skilled in the art to use other photovoltaic cells 3 than cells based on monocrystalline or polycrystalline silicon such as for example organic cells or inorganic thin layers, without leaving of the scope of the present invention.

Thus, the manufacturing method described above allows in a simple way, thanks to the deposition of a decorative film on the front encapsulation layer of the photovoltaic cells, to obtain flexible photovoltaic panels whose weight is reduced and having a decorative pattern. to limit their visual impact, for example for camouflage or to standardize with the existing colors of a building or on the contrary to produce a visual message such as a logo or writing. In addition, a front layer having for example anti-fouling, anti-scratch or anti-reflection properties can be added in the manufacturing process.

Claims (12)

1. Method for manufacturing a flexible laminate (1) of photovoltaic cells (3) in which a laminated layer of photovoltaic cells (3) connected together and front (5) and rear (7) layers is assembled by lamination encapsulation of the layer of photovoltaic cells (3), (101) a decorative film (9) is deposited on the front encapsulation layer (5), (102) a protective layer (11) is deposited on the decorative film ( 9) (103). 2. The manufacturing method according to claim 1 wherein the deposition of the decorative film (9) is carried out by a vapor deposition process. 3. The manufacturing method according to claim 1 or 2 wherein the decorative film (9) comprises an interferometric filter. 4. Manufacturing method according to one of the preceding claims wherein the decorative film (9) is a film comprising a colored pattern. 5. Manufacturing process according to any one of the preceding claims, in which the photovoltaic cells (3) are silicon-based cells. 6. The manufacturing method according to any one of the preceding claims wherein the protective layer (11) is a transparent varnish. 7. The manufacturing method according to claim 6, in which the varnish is produced from a polymer-based material chosen from polyurethane varnishes, acrylic type varnishes, polyester type varnishes, silicone type varnishes, or even varnishes. epoxy type. 8. The manufacturing method according to claim 6 or 7 wherein the varnish has anti-fouling properties such as a water repellency or anti-reflection properties or anti-scratch properties. 9. The manufacturing method according to any one of claims 1 to 5 wherein the protective layer (11) comprises a flexible transparent film forming an additional layer 17 bonded to the decorative film by an adhesive 15. 10. The manufacturing method according to claim 9 wherein the adhesive is made of the same material as the encapsulation layers and comprises ethylene vinyl acetate "EVA". 11. The manufacturing method according to claim 9 or 10 wherein the additional layer 17 has anti-fouling properties, in particular a predetermined roughness and / or a water repellency or anti-reflective properties or anti-scratch properties. 12. Manufacturing method according to one of the preceding claims wherein the assembly by lamination also comprises a rear connection layer (13) disposed at the rear of the rear encapsulation layer (7).