METHOD THEREOF

TECHNICAL FIELD

The present invention concerns the field of the reflection of solar radiation. In particular, the present invention concerns the field of reflecting sheets used in solar plants. Therefore, the present invention concerns a reflecting stratiform structure configured so as to reflect incident radiation, a method for forming such a reflecting stratiform structure and a solar mirror, with a production method thereof, comprising such a reflecting stratiform structure.

BACKGROUND

Currently, in order to have more sustainable development, there is a great need to exploit solar radiation as much as possible to produce electrical energy. However, at the same time it is clear that the concentration of solar energy is relatively low and therefore the concentration of energy becomes necessary. An example is that of the use of parabolic mirrors adapted to concentrate the incident radiation on them towards a solar collector positioned in the focus of the parabola. Another example is that provided by the solar mirrors used in a photovoltaic system to allow the incident radiation between two adjacent rows of photovoltaic panels, which would otherwise be dispersed, to be reflected onto them through mirrors so as to be recovered.

Concerning this last example, it should be noted that large photovoltaic systems provide for the positioning of the photovoltaic panels with a precise inclination with respect to the ground so as to maximise the radiation captured and, due to the fact that it is not wished to in any way obscure two successive rows of photovoltaic modules, there will be a predetermined distance between two adjacent rows of photovoltaic modules. This thus results in the fact that a part of the solar radiation will land in the space comprised between two adjacent rows of photovoltaic modules. Therefore, thanks to the positioning of such solar mirrors, it is possible to direct such radiation that would otherwise be dispersed towards the adjacent photovoltaic modules.

In the same way, there is currently a need to have reflecting structures that are cost-effective, efficient and long-lasting. Indeed, with regard to cost-effectiveness, it is clear that a fundamental problem is that of a reduction of the production costs to obtain systems that are competitive with other energy sources. Moreover, with regard to efficiency and lifetime, it is clear that, while on the one hand it is necessary for such structures to withstand bad weather, humidity and big temperature changes over a long time period, thus requiring a covering layer, on the other hand it is necessary for such structures comprising such a covering layer to be very transparent to allow the incident radiation to reach the reflecting layer and thus be reflected as much as possible.

The present invention thus has the purpose of providing a reflecting stratiform structure configured so as to reflect the incident radiation coming from the upper side with respect to the structure which at the same time is cost-effective, with a high degree of reflectivity and strong. Moreover, the present invention comprises a method for forming such a reflecting stratiform structure and a solar mirror, with a production method thereof, comprising such a reflecting stratiform structure.

SUMMARY

The present invention is based on the idea of providing a transparent thermoplastic film arranged above and in direct contact with a reflecting layer.

In the present invention, the terms“above",“below”,“lower”,“upper”,“top",� ��bottom”,“front” and “rear”, unless otherwise specified, refer to the relative arrangement of the various layers considering a section view of the final architecture of the structure in which the surface facing towards the sun occupies the highest level.

According to an embodiment of the present invention a reflecting stratiform structure is provided that is configured so as to reflect the incident radiation coming from an upper side with respect to the structure, said structure comprising a reflecting layer, preferably metallic, and a first transparent thermoplastic film arranged above and in direct contact with the reflecting layer so that the incident radiation can pass through the first transparent thermoplastic film and be reflected by the reflecting layer. This solution is particularly advantageous since it makes it possible to have a reflecting layer in direct contact with a transparent thermoplastic film arranged above it and thus capable of protecting the reflecting layer from external agents. At the same time, the transparent thermoplastic film allows the incident radiation to be transmitted through it.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which the first transparent thermoplastic film is made of polyethylene terephthalate (PET), preferably in amorphous form. As well-known, PET is an electrically insulating material, having a high chemical resistance and able to withstand a wide range of temperatures. Therefore, thanks to these properties, and thus thanks to the use of PET, it is possible to have an excellent insulator for the reflecting layer. Moreover, thanks to the characteristics of PET, it is possible to achieve very high moulding speeds. In addition, thanks to the amorphous form, PET is a perfectly transparent material capable of transmitting almost all of the incident radiation on it, thus having a very low reflection coefficient.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which the first thermoplastic film has a thickness comprised between 50 pm and 100 pm, preferably equal to 75 pm. This solution is particularly advantageous since it makes it possible to have a layer capable of effectively insulating the reflecting layer preventing external agents from interacting with the reflecting layer. Moreover, the low thickness of the first thermoplastic film makes it possible to have a reflecting stratiform structure having a relatively low total thickness.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which such a structure further comprises a coating layer positioned above and preferably in direct contact with the first thermoplastic film. This solution is particularly advantageous since it makes it possible to have a coating layer capable of further protecting the reflecting layer. Moreover, such a coating layer will preferably have a surface pattern that will make it possible to capture the greatest amount of incident radiation and convey it efficiently towards the reflecting layer.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which such a reflecting stratiform structure further comprises a second thermoplastic film, preferably polyethylene terephthalate (PET), arranged below the reflecting layer, wherein the second thermoplastic film has a thickness preferably comprised between 75 pm and 350 pm, more preferably equal to 150 pm. This solution is particularly advantageous for three different reasons. The first concerns the fact that having a thermoplastic film arranged lowerly with respect to the reflecting layer ensures a protection of the reflecting layer against external agents such as atmospheric agents and also ensures an electrical insulation. Moreover, secondly, having such a thickness ensures the possibility of having a self-supporting reflecting stratiform structure since such a thermoplastic film can also act as a support. Thirdly, as well known, PET is an electrically insulating material, having a high chemical resistance and able to withstand a wide range of temperatures. Therefore, thanks to these properties, it is possible to have an excellent insulator for the reflecting layer also at the bottom.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which the second thermoplastic film is attached to the reflecting layer through an adhesive layer having a thickness preferably comprised between 6 pm and 12 pm, more preferably equal to 8 pm. This solution is particularly advantageous since it makes it possible to ensure fixation between the two layers. The fixation is ensured by a layer having a constant thickness and therefore this layer ensures the possibility of having a reflecting stratiform structure having a constant thickness. Indeed, having simple glue would run the risk of having some points with more glue and some without, thus having non-constant thicknesses.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which the reflecting stratiform structure further comprises a pressure-sensitive adhesive layer positioned below the second thermoplastic film so as to be able to apply the stratiform structure to an outer body, wherein the adhesive layer is preferably in direct contact with the second thermoplastic film. This solution is particularly advantageous since it makes it possible to apply the reflecting stratiform structure to an outer support layer extremely easily. Indeed, it will suffice to simply remove the film that covers the pressure-sensitive adhesive layer and apply a pressure on the reflecting stratiform structure in contact with the support layer to fix the reflecting stratiform structure to the support layer.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which the reflecting stratiform structure further comprises an amorphous side positioned below the second thermoplastic film so as to be able to apply the stratiform structure to an outer body, wherein the amorphous side is preferably in direct contact with the second thermoplastic film. This solution is particularly advantageous since it makes it possible to apply the reflecting stratiform structure to an outer support layer extremely easily thanks to simple thermowelding.

According to a further embodiment of the present invention a reflecting stratiform structure is provided in which the reflecting stratiform structure is supplied in a reel. Such a solution is particularly advantageous since it makes it possible to have a finished product wound in a reel and ready to be applied on any type of surface. Moreover, thanks to the fact that it is possible to supply such a structure in a reel, there is the possibility of occupying very little space and the possibility of having very simple and quick application processes of such a structure to support layers.

According to a further embodiment of the present invention a solar mirror is provided that is configured so as to reflect the light striking it towards an outer body, wherein the solar mirror comprises a reflecting stratiform structure according to an embodiment of the present invention and a support layer arranged below and in direct contact with the reflecting stratiform structure configured so as to support the reflecting stratiform structure and preferably having a thickness comprised between 0.5 mm and 2 mm, more preferably equal to 1.2 mm. This solution is particularly advantageous since it makes it possible to fix the reflecting stratiform structure on a support layer so as to be positioned in a fixed manner and have a predetermined shape ensured by the support layer by which it is supported, and preferably to which it is fixed.

According to a further embodiment of the present invention a solar mirror is provided in which such a solar mirror is used as reflecting mirror to reflect the incident radiation towards a photovoltaic module positioned at a predetermined distance with respect to the solar mirror. This solution is particularly advantageous since it makes it possible to use such a reflecting stratiform structure to reflect the incident radiation towards a photovoltaic module so as to increase the amount of energy striking such a photovoltaic module.

According to a further embodiment of the present invention a solar mirror is provided in which the solar mirror is used as a mirror for parabolic surfaces configured so as to concentrate the incident radiation towards a solar collector. This solution is particularly advantageous since it makes it possible to focus the incident radiation towards a point in which a collector is positioned, which can for example be represented by a photovoltaic panel or by a simple collector in the case of a thermodynamic solar plant.

According to a further embodiment of the present invention a method for forming a reflecting stratiform structure is provided that is configured so as to reflect the incident radiation coming from an upper side with respect to the structure comprising the following steps: a. providing a reflecting layer, preferably metallic; b. providing a first thermoplastic film above and in direct contact with the reflecting layer so that the incident radiation can pass through the first transparent thermoplastic film and be reflected by the reflecting layer.

This solution is particularly advantageous since it makes it possible to have a reflecting layer in direct contact with a transparent thermoplastic film arranged above it and thus capable of protecting the reflecting layer from external agents. At the same time, the thermoplastic film allows the incident radiation to be transmitted through it.

According to a further embodiment of the present invention a method is provided that further comprises the following step: c. providing a second thermoplastic film below the reflecting layer, wherein the second thermoplastic film is preferably applied through an adhesive layer to the lower surface of the reflecting layer.

This solution is particularly advantageous for three different reasons. The first concerns the fact that having a thermoplastic film arranged lower!y with respect to the reflecting layer ensures a protection of the reflecting layer against external agents such as atmospheric agents and also ensure electrical insulation. Moreover, secondly, such a layer ensures the possibility of having a self-supporting reflecting stratiform structure since such a thermoplastic film can also act as a support. Thirdly, in the case in which such a layer is made of PET, as well known it is an electrically insulating material, having a high chemical resistance and able to withstand a wide range of temperatures. Therefore, thanks to these properties, it is possible to have an excellent insulator for the reflecting layer also at the bottom.

According to a further embodiment of the present invention a method is provided that further comprises the following step: d. providing a coating layer above the first thermoplastic film.

This solution is particularly advantageous since it makes it possible to have a coating layer capable of further protecting the reflecting layer. Moreover, such a coating layer will preferably have a surface pattern that will make it possible to capture the greatest amount of incident radiation and convey it efficiently towards the reflecting layer.

According to a further embodiment of the present invention a method is provided in which the reflecting layer is supplied on a first thermoplastic film through vacuum deposition. Such a solution is particularly advantageous since it makes it possible to use a prior art like vacuum deposition that makes it possible to have a perfectly homogeneous surface despite the very thin thickness of the layer. In particular, in the present invention, the term“vacuum deposition” is meant to indicate the family of processes used to deposit layers of material atom by atom or molecule by molecule on a solid surface. These processes operate at pressure much below atmospheric pressure (i.e. a vacuum). The layers deposited can vary from a thickness of one atom up to millimetres, forming independent structures. The process can be qualified based on the vapour source; the physical deposition from vapour uses a liquid or solid source and the chemical deposition from vapour uses - a chemical vapour. According to a further embodiment of the present invention a method is provided in which the reflecting layer is supplied on a first thermoplastic film through vacuum thermal evaporation. Such a solution is particularly advantageous since, through the vacuum thermal evaporation, it is possible to have a perfectly homogeneous surface despite the very thin thickness of the layer. Moreover, the vacuum thermal evaporation is very advantageous also from the economic point of view, thus making it possible to have low production costs. In the present invention, the term vacuum thermal evaporation is meant to indicate a particular form of vacuum deposition in which a source material is evaporated in the vacuum. The vacuum allows the particles of vapour to travel directly on the target object (substrate), where they condense once again to solid state.

According to a further embodiment of the present invention a method is provided in which the reflecting layer is supplied on a first thermoplastic film through sputtering. In the present invention, the term sputtering is meant to indicate a particular form of vacuum deposition in which there is emission of atoms, ions or molecular fragments from a solid material called target bombarded with a beam of energetic particles (generally ions).

According to a further embodiment of the present invention a method is provided that further comprises the following step: e. applying a pressure-sensitive adhesive layer lowerly with respect to the second thermoplastic film so as to be able to apply the stratiform structure to an outer body, wherein the adhesive layer is preferably applied in direct contact with the second thermoplastic film.

This solution is particularly advantageous since it makes it possible to apply the reflecting stratiform structure to an outer support layer extremely easily. Indeed, it will suffice to simply remove the film that covers the pressure-sensitive adhesive layer and apply a pressure on the reflecting stratiform structure in contact with the support layer to fix the reflecting stratiform structure to the support layer.

According to a further embodiment of the present invention a method is provided that further comprises the following step: f. applying a thermoweldable amorphous side on the lower surface of the second thermoplastic film.

This solution is particularly advantageous since it makes it possible to apply such a reflecting stratiform structure to an outer body through hot rolling. According to a further embodiment of the present invention a method for producing a solar mirror for solar concentrators comprising a reflecting stratiform structure produced according to one of the embodiments of the present invention is provided, wherein the reflecting stratiform structure is applied to a support layer, preferably a metal foil, through hot rolling. This solution is particularly advantageous since the application through hot rolling makes it possible to have an effective long- lasting fixation of the two layers. Moreover, the hot rolling makes it possible to have a high production speed.

According to an embodiment of the present invention a reflecting stratiform structure is provided that is produced according to a method of any one of the embodiments listed above. In particular, a reflecting stratiform structure in which the reflecting layer is supplied on a first thermoplastic film through vacuum deposition. Such a solution is particularly advantageous since it makes it possible to use a prior art like vacuum deposition that makes it possible to have a perfectly homogeneous surface despite the very thin thickness of the layer. According to the present embodiment there is a particularly dense and pure reflecting layer. In particular, the term density is meant to indicate the presence of micro pores or pinholes on the surface of the reflecting layer that would otherwise alter the reflection properties of the reflecting layer. Moreover, the term purity is meant to indicate the presence of foreign elements inside the reflecting layer. Indeed, thanks to the use of vacuum deposition it will thus be possible to select the particles that will form the reflecting layer, effectively preventing foreign elements from being able to be deposited in the reflecting layer. Such characteristics (density and purity) cannot be quantified easily but, however, those skilled in the art are capable, with extreme certainty, viewing the reflecting layer with suitable means, such as a microscope, of recognising that such a reflecting layer has been produced through vacuum deposition.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will be described with reference to the attached figures in which the same reference numerals and/or reference marks indicate the same parts and/or similar parts and/or corresponding parts of the system.

Figure 1 schematically shows a section of a reflecting stratiform structure according to an embodiment of the present invention;

Figure 2 schematically shows a section of a reflecting stratiform structure positioned on a support layer according to an embodiment of the present invention; Figure 3 schematically shows a reflecting stratiform structure used as reflecting system for a solar system of the retrofit type according to an embodiment of the present invention;

Figure 4 schematically shows a reflecting stratiform structure used as parabolic solar concentrator in a thermodynamic solar plant according to an embodiment of the present invention;

Figure 5 schematically shows a reflecting stratiform structure used as photovoltaic concentrator in a photovoltaic system according to an embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, the present invention is described with reference to particular embodiments, as illustrated in the attached tables of drawings. However, the present invention is not limited to the particular embodiments described in the following detailed description and represented in the figures, but rather the described embodiments simply exemplify the various aspects of the present invention, the purpose of which is defined by the claims. Further modifications and variations of the present invention will become clear to those skilled in the art.

In the present description, the term film is meant to indicate a layer of thin planar material that can be applied above a surface, preferably flat, and which has a preferably constant thickness along the plane on which it extends. Moreover, the term thermoplastic film is thus meant to indicate a layer of a substance that is thermoplastic and that thus has the property of reversibly acquiring plasticity, and thus mouldability, under the action of heat.

Figure 1 schematically shows a reflecting stratiform structure 100 which makes it possible to reflect the incident radiation coming from an upper side with respect to such a structure 100. Hereinafter, the various layers comprised in such a stratiform structure 100 will be described. However, it should be emphasised that it is clear to those skilled in the art that some layers can be omitted or other layers can be added without departing from the scope of the invention which is defined by the attached claims.

In the particular example represented in figure 1 , a transparent thermoplastic film 102 is positioned above and in direct contact with a reflecting layer 103 so as to protect the reflecting layer 103 beneath. Indeed, it is important to have insulation between the reflecting layer and the outside so that the external agents, like for example humidity, do not deteriorate the reflecting layer 103.

Such a transparent thermoplastic film described above, used in such a film 102, can for example be a layer of PET having a thickness for example comprised between 50 pm and 100 pm, wherein such a thickness is preferably equal to 75 pm. Alternatively, the layer 102 can be a layer of fluorinated film (FEP, PVF, PVDF) or a layer of acrylate film (PMMA). The use of fluorinated or acrylate films is particularly advantageous since such materials are particularly resistant to atmospheric agents.

The reflecting layer 103, as will be explained in greater detail hereinafter, is preferably a metallic layer of aluminium in the case of a solar plant of the retrofit type or a metallic layer of silver in the case of a solar concentrator. Such a reflecting layer 103 has the purpose of reflecting the greatest possible amount of incident light. Therefore, thanks to the metallic layer made for example of silver or aluminium, the incident light can be reflected, even more than 94% in the case in which it is silver. Such a reflecting layer 103 has a very thin thickness for example equal to 0.1 pm.

Therefore, the incident solar radiation on such a reflecting stratiform structure 100 can penetrate through such a transparent thermoplastic film 102, be reflected by the reflecting layer 103 and come back out from such a structure passing again through such a transparent thermoplastic film 102. Thereby, the layer 102 will have a high transmission coefficient of the radiation so as to allow the transmission of almost all of the incident radiation through it along both directions: both the radiation coming from above and that reflected by the reflecting layer 103 positioned below it.

A transparent protective coating layer of solidified thermoplastic resin 101 is positioned above the layer 102. The transparent protective coating of solidified thermoplastic resin 101 (hereinafter called“transparent protective coating layer 101”) makes it possible to provide more protection to the reflecting layer 103. Such a transparent protective coating layer 101 can have either a perfectly smooth surface or a pattern to be able to better interact with light. However, it is important that such a transparent protective coating layer 101 also has a high transmission coefficient so as to allow the greatest amount of incident radiation possible to be transmitted through it.

Below the reflecting layer 103, in the particular example represented in the figures, a second thermoplastic film 105 is positioned which is applied to the reflecting layer 103 through an adhesive layer 104 thus positioned between the reflecting layer 103 and the second thermoplastic film 105.

Such a thermoplastic film used in the thermoplastic film 105 can, also in this case, be represented by PET even if in this case it is not necessary for it to be a transparent material since, being located at the rear with respect to the reflecting layer, it clearly does not perform the task of reflecting the incident light as on the other hand occurs for the first thermoplastic film 102 described previously. As far as the thicknesses are concerned, the second thermoplastic film 105 can have a thickness comprised between 75 pm and 350 pm and preferably it is equal to 150 pm. Such a thickness will however depend greatly on the application inside which such a reflecting stratiform structure 100 is applied. In the case for example in which it is wished to have a self-supporting structure, it will be preferable to have a very high thickness of such a layer 105, equal for example to 350 pm. On the other hand, in the case in which the reflecting stratiform structure 100 is subsequently applied to a support layer, the layer 105 can also have a much lower thickness, for example equal to 75 pm.

The adhesive layer 104 that makes it possible to fix the layer 105 to the reflecting layer 103 can have a thickness comprised between 6 pm and 12 pm, preferably equal to 8 pm.

Therefore, as described, the reflecting layer 103 will be positioned between two thermoplastic films, such as PET, which thus make it possible to“sandwich” the reflecting layer protecting it from external agents. Moreover, it is clear that, being a thermoplastic film, it is also possible in this way to electrically insulate the reflecting layer preventing possible electromagnetic alterations thereof. Indeed, the layer 105 will also have the advantage of providing a protection against the galvanic corrosion that there would be between the reflecting layer 103 (which as stated is preferably made of metallic material) and a support layer on which such a structure 100 is applied, in the case in which the support layer is metallic.

Below such a second thermoplastic film 105, in the case in which it is wished to apply the reflecting stratiform structure 100 to an outer body, it is possible to install a pressure-sensitive adhesive layer 106 in direct contact with the second thermoplastic film 105. In this way, by applying a simple pressure on such a stratiform structure, it will be possible to apply the structure 100 to an outer support. It is clear that, below such a pressure-sensitive adhesive layer 106, it is possible to apply a tear-away coating (not depicted) that can be removed before the application of the reflecting stratiform structure 100 to an outer element.

Alternatively, the lower side of the second thermoplastic film 105 can be made so that such a surface is weldable, for example thermoweldable. Indeed, in the state of the art there are known amorphous surfaces applicable to stratiform structures, like the one described here, which make it possible to apply the structure itself to an outer body through hot welding.

The reflecting stratiform structure 100 described above can be supplied in reels of great length, also equal for example to 1000 m of length. For example, a reel can have a length of the order of 1000 m and a width of the order of 1.5 m. Figure 2 shows, as described earlier, a support layer 200 on which such a reflecting stratiform structure 100 described earlier is positioned. Such a support layer 200 can preferably have a thickness comprised between 0.5 mm and 2 mm, more preferably equal to 1.2 mm.

The surface of the support layer 200 can have a roughness (Ra) equal to 2 thus making it possible to have a surface of the support layer 200 that is rough enough. The support layer 200 can be made for example from steel or aluminium, above which the reflecting stratiform structure 100 can be applied.

Figures 3 to 5 represent possible applications of the reflecting stratiform structure 100 described above.

As shown in figure 3, the reflecting stratiform structure 100 can be applied as a reflecting system for a solar system of the retrofit type. As is indeed known in the state of the art, due to the optimal inclination of the photovoltaic modules 99 that makes it possible to absorb the greatest possible amount of solar radiation, empty spaces are formed between two adjacent rows of photovoltaic modules 99. Such spaces are due to the fact that it is wished to prevent the possibility that two rows of photovoltaic modules inclined with respect to the ground overshadowing one another. For this reason, a part of the solar radiation will be dispersed being partially absorbed by the ground at such empty spaces.

It therefore becomes necessary to recover such energy, which would otherwise be dispersed, through solar mirrors configured so as to reflect the incident radiation on them towards a photovoltaic module so as to at least partially recover the radiation that would otherwise be dispersed. It is calculated that the increase in energy produced thanks to such mirrors is of the order of 10-15% at a latitude of 23°.

In the present invention, it has therefore been discovered that it is very advantageous to make such mirrors through a reflecting stratiform structure 100 in which the reflecting layer 103 is arranged below and in direct contact with a transparent thermoplastic film 102 capable of effectively protecting the reflecting layer 103 and of allowing almost all of the incident light to penetrate through it.

In this case, given the extension that such mirrors must cover and the relatively low concentration of incident radiation, it will be preferable to make such a reflecting layer 103 from aluminium, making it possible to have relatively low production costs. As shown in figures 4 and 5, such a reflecting stratiform structure 100 can also be used as parabolic solar concentrator in a thermodynamic solar plant (figure 4) and as photovoltaic concentrator in a photovoltaic system (in figure 5).

In this case, given the high concentration of incident radiation, it will be preferable to make the reflecting layer 103 of the reflecting stratiform structure 100 from silver having a very high reflection coefficient that makes it possible to reflect even more than 94% of the incident radiation.

In general, the reflecting stratiform structure 100 can be applied directly on a support layer 200 for example made from metal such as iron or polymeric surfaces.

Hereinafter, the production method of a reflecting stratiform structure 100 according to a particular embodiment of the present invention is described.

As a first step a first thermoplastic film 102, like the one described earlier, is provided, on which a reflecting layer 103 is applied. The metallic reflecting layer 103 can be applied on the lower surface of the first thermoplastic film 102 through vacuum deposition which makes it possible to obtain a very thin thickness of the layer and, despite this, a perfectly homogeneous surface, thus having a low bulk and low production costs.

Indeed, as described earlier, according to the present embodiment it is possible to have a reflecting layer 103 having a very thin thickness, for example equal to 0.1 pm. In particular, according to the present invention, thanks to the production method described above, a reflecting layer is obtained having a thickness comprised between 0.01 pm and 0.2 pm.

Moreover, according to preferred embodiments, it is possible to use specific vacuum deposition methods. In particular, the inventor has discovered that it is particularly advantageous to use vacuum thermal evaporation on the layer of transparent thermoplastic film 102. Alternatively, the inventor has discovered that advantageous properties can also be obtained with sputtering.

According to the production methods of the reflecting layer described above a reflecting layer 103 is obtained that is particularly dense and pure.

In particular, the term density is meant to indicate the presence of micro pores or pinholes on the surface of the reflecting layer that would otherwise alter the reflection properties of the reflecting layer.

Moreover, the term purity is meant to indicate the presence of foreign elements inside the reflecting layer 103. Indeed, thanks to the use of vacuum deposition it will thus be possible to select the particles that will form the reflecting layer effectively preventing foreign elements from being able to deposit in the reflecting layer 103.

Such characteristics (density and purity) are not easily quantifiable but, nevertheless, those skilled in the art are able, with extreme certainty, viewing the reflecting layer with suitable means, such as a microscope, to recognise that such a reflecting layer 103 has been produced through vacuum deposition.

Moreover, the production methods listed above are valid both in the case in which the reflecting layer is made from aluminium and from silver.

Above the first thermoplastic film 102, a transparent protective coating layer 101 is provided so as to protect the underlying layers from external agents, like for example humidity. Such a transparent protective coating layer 101 can have a thickness of between 4 pm and 50 pm, and preferably equal to 15 pm.

Below the reflecting layer 103, a second thermoplastic film 105 is provided which is applied to the reflecting layer 103 through an adhesive layer 104.

Below the second thermoplastic film 105 it is alternatively possibly to provide a pressure-sensitive adhesive layer 106, so as to be able to apply the reflecting stratiform structure 100 to an outer body, or the second thermoplastic film 105 can be provided with a lower amorphous side which is weldable, for example thermowe!dable.

Therefore, there will be two different methods of applying the reflecting stratiform structure 100 described above to a support layer 200 arranged lowerly with respect to the structure 100.

Indeed, in the case in which the structure comprises a pressure-sensitive adhesive layer 106, the structure 100 can be applied to the support layer 200 by simply exerting a pressure on the structure 100 against the support layer 200. Such a solution is preferably applicable in the case in which the solar mirror 1000 that will thus be formed is used for concentrators, as shown in figures 4 and 5. The reason is due to the fact that, since the concentrators are normally curvilinear surfaces, it will in this way be easier to apply the reflecting stratiform structure 100 to such surfaces.

On the other hand, in the case in which the structure comprises a thermoweldable amorphous lower side, the reflecting stratiform structure 100 can be applied to the support layer 200, which as stated can be a metal foil, through hot rolling. Such a solution is preferably applicable in the case in which the solar mirror 1000 that will be formed is used as a reflecting mirror to reflect the incident radiation towards a photovoltaic module positioned at a predetermined distance with respect to such a solar mirror 1000. The reason is due to the fact that in such types of mirrors normally the surfaces are flat and therefore hot rolling is advantageous.

Even if the present invention has been described with reference to the embodiments described above, it is clear to those skilled in the art that it is possible to make different modifications, variations and improvements of the present invention in light of the teaching described above and in the attached claims, without departing from the object and from the scope of protection of the invention.

For example, even if the presence of a single transparent protective coating layer 101 has been described, it is possible for many coating layers to be provided arranged one on top of the other. Moreover, even if not specifically described, it is clear that such a reflecting stratiform structure 100 can be applied in various fields, like for example construction. Indeed, such a structure 100 can be applied for example on the surfaces of buildings to allow incident light to be reflected and thus have better heat insulation.

Finally, fields that are deemed known by those skilled in the art have not been described in order to avoid needlessly excessively overshadowing the invention described.

Consequently, the invention is not limited to the embodiments described above, but is only limited by the scope of protection of the attached claims.