Method for applying a glare-reducing coating to a substrate, coating liquid, solar glass or solar film having a coating, solar cell and / or solar module, and solar installation

Abstract

The invention relates to a method for applying a glare-reducing coating to a substrate, in particular to a solar glass and / or to a solar film, wherein a structured coating for refracting and / or scattering incident light is applied to the substrate, comprising the following steps: - providing the substrate, so that the substrate is available for the application of the coating, - applying a coating liquid to the substrate, so that a liquid raw layer is produced on the substrate, - pre-curing a surface of the coating liquid by means of pre-curing radiation radiated at the surface, so that the surface is pre-cured and a supporting layer located between the surface and the substrate remains liquid and / or at least is only gelled and the surface forms a random micro-structure as a result of the radiating of the pre-curing radiation, - curing the surface and the supporting layer by means of curing radiation radiated at the previously liquid raw layer, so that the coating composed of the cured surface and the cured supporting layer is formed by means of the coating liquid from the raw layer, so that a glare-reducing coating is applied to the substrate.

Description

Method for applying a bend-reducing coating on a substrate, coating liquid, Solar glass or solar film with a coating, Solar cell and / or solar module and solar system

[0001] The invention relates to a method for applying a light-reducing coating to a substrate, in particular to a solar glass and / or to a solar film, wherein a structured coating for refracting and / or scattering incident light is applied to the substrate. The invention further relates to a coating liquid, a solar glass having such a coating with an irregular microstructure, a solar cell and / or a solar module, wherein the solar cell and / or the solar module comprise a solar glass, and a solar system having a plurality of solar cells and / or a plurality of solar modules.

[0002] Especially for photovoltaic cells, also called solar cells, it is necessary to design a corresponding, usually glass, surface to reduce light reflection, i.e., to reduce or prevent reflection of incident light, so that the solar cell achieves the highest possible solar yield or power output. Furthermore, this avoids reflections that are unpleasant for observers and / or relevant to building regulations.

[0003] Known substrates, in particular solar glass and / or solar films, are pressed with a uniform microstructured pattern, for example from a matrix or using a rolling process, so that this uniformly structured surface has a significantly reduced radiation behavior compared to reflected radiation by at least one to three orders of magnitude. Such microstructures are molded from a master, i.e. the matrix or corresponding rollers, or are present as natural regular or irregular microstructures in glass such as rolled glass or float glass and are designed, in particular as a film or directly as rolled glass, then bonded, i.e. glued or connected, to a front glass or other cover of photovoltaic modules. Etched glasses that can be used as solar glass are also known.However, these processes are often complex and sometimes require specific tools and usually multiple production steps. Furthermore, the achievable surface structures are comparatively coarse, for example, with structures on the order of millimeters or at least a few hundred microns. Although glasses modified by etching can exhibit finer structures, the manufacturing process is complex, and the result is sometimes unsatisfactory for the specific purpose of glare-free glass.

[0004] US 2013 / 0129980 A1 discloses a method for producing abrasion-resistant matting for plastic substrates, in particular a substrate made of a PMMA coating. This involves using acrylate-based coatings that are irradiated with excimer radiation.

[0005] In "UV curing and matting of acrylate coatings reinforced by nano-silica and mirco-corundum particles (Parti)" (Frank Bauer, Roman Flyunt et al., 2007 Elsevier BV), the creation of matte surfaces with embedded nanoparticles is described. For this purpose, acrylate-based coatings are used.

[0006] In "UV curing and matting of acrylate nanocomposite coatings by 172nm excimer irradiation (Part 2)" (Frank Bauer, Ulrich Decker et al., 2008 Elsevier BV), the generation of a coating from a liquid phase is also described, using acrylic and epoxy-based coating systems.

[0007] The publication "VUV-induced micro folding of acrylate-based coatings, 2. Characterization of surface properties" (Rolf Schubert, Frank Frost et al., 2009 Elsevier BV) shows the creation of microstructures in coatings using the irradiation of high-energy light to create a microfold.

[0008] US 2006 / 0019114 A1 discloses a method for Creating a nanostructured surface coating.

[0009] US 2008 / 0135091 A1 describes a method for Manufacturing a solar panel with an increased luminous efficacy .

[0010] The known coatings are either not weather-resistant enough or do not have the desired optical properties, i.e. low glare with simultaneous optimised light transmission.

[0011] The object of the invention is to improve the state of the art.

[0012] The object is achieved by a method for applying a light-reducing coating to a substrate, in particular to a solar glass and / or to a solar film, wherein a structured coating for refracting and / or scattering incident light is applied to the substrate, comprising the following steps: - Providing the substrate so that the substrate is available for applying the coating, - applying a coating liquid to the substrate so that a liquid raw layer is created on the substrate, - Pre-hardening of a surface of the Coating liquid by means of pre-curing radiation radiated onto the surface with a pre-curing dose of at least 60, in particular 60 to 200, in particular 100 to 200 mJ / cm 2, so that the surface is pre-cured and a support layer arranged between the surface and the substrate is still liquid and / or at least only gelled and the surface is cured by irradiating the pre-curing radiation with the pre-curing dose of at least 60, in particular 60 to 200, in particular 100 to 200 mJ / cm 2 a random microstructuring is formed, - Curing the surface and the base layer by means of curing radiation radiated onto the previously liquid raw layer, so that the coating of the cured surface and the cured base layer is formed by means of the coating liquid from the raw layer, so that a bend-reducing coating is applied to the substrate.

[0013] This enables a continuous, simple and cost-optimized application and especially pre-curing for the formation of the random microstructuring of a corresponding coating on the substrate. In addition, no complex and expensive tools are required. In particular, corresponding matrices or structured rollers can be dispensed with. It should be noted that a pre-curing dose of more than 60 mJ / cm 2 used to achieve the effect according to the invention. In addition, the pre-curing dose can also be limited, in particular to 200 mJ / cm 2 in order to be energy efficient, for example.

[0014] The comparatively high pre-curing dose of more than 60, in particular 60 to 200, in particular 100 to 200 mJ / cm 2is required to trigger a photo-frontal polymerization within the coating liquid, particularly with photons of the respective wavelengths. This also a greater penetration depth of the crosslinking is created in a short time, thus producing structures with a desired larger aspect ratio.

[0015] In particular, a gloss level of <0.3 / <l , 5 / <l , 5 bei 20° / 60° / 85° erzeugt. Die Messung dieses „Glanzgrades" erfolgt dabei nach DIN EN ISO 2813 in der zum Zeitpunkt der vorliegenden Anmeldung geltenden Fassung.

[0016] The following terms are explained in this context:

[0017] A "method for applying a glare-reducing coating" is a technical process that uses appropriate steps to ensure that a "glare-reducing coating" is used, i.e., a coating that positively improves the reflection behavior to increase irradiation and / or reduce back reflection. In addition to reducing the actual reflection, the targeted scattering and / or deflection of light can also reduce back reflection, for example, by distributing or changing the angle of the outgoing light. As a measure of glare reduction, a reference of a maximum of 100,000 cd / m² can be used here. 2 , maximum 50,000 cd / m 2 or a maximum of 25,000 cd / m 2 or a maximum of 10,000 cd / m 2, depending on the respective requirements and also depending on the respective angles to the vertical. The corresponding light-reducing coating is applied to a "substrate", for example on a solar film, a solar glass or another carrier, in particular transparent or a partially transparent carrier, so that the corresponding substrate can then be used to produce a solar module. For example, an appropriately pretreated solar film can then be applied to a solar module; however, a solar module or a cover glass of a solar module can also serve directly as the substrate and be treated accordingly. The substrate can also be formed by a solar cell itself, i.e. the solar cell, which is made of silicon, for example, can be coated directly, provided, for example, that the additional weight of solar glass is to be avoided.It should be noted that the terms "solar film" and "solar glass" can refer, on the one hand, to a film produced, for example, from a plastic, and, on the other hand, to a correspondingly processed glass for use in a solar application, but are generally synonymous with a layer covering and / or protecting the solar cell, in particular a translucent layer. Thus, the method according to the invention is generally suitable for providing corresponding translucent layers for covering and / or protecting solar cells with a corresponding light-reducing coating.

[0018] A "solar cell" typically refers to a silicon wafer for photovoltaics, which is configured to generate electricity by means of connecting contacts. A "solar module," on the other hand, describes deployable and applicable units, for example, robustly designed with a frame, in which one or more solar cells are installed and electrically contacted. Such a solar module can, for example, also have additional electrical connections and / or switching devices, for example to enable electrical power to be fed into a power grid.

[0019] A "structured coating" describes a coating which has corresponding elevations and depressions, in particular in the thickness direction, so that a physical structure is introduced into the coating which is particularly suitable for refracting or scattering incident light. "Incident light" in this context describes, for example, sunlight which strikes the solar glass and / or the solar film and can then be used for a solar cell arranged behind the solar glass or behind the solar film after the incident light has been refracted and / or scattered.A "breaking" of the incident light describes the deflection or redirection of the incident light, in particular at transition areas between different materials, for example from an environment into the solar film, whereas a "scattering" describes a diffuse and / or in particular disordered redirection and / or deflection of incident light.

[0020] The "provision" of the substrate describes the introduction of the substrate into a corresponding system or to a corresponding workstation, for example in a process, so that the substrate is in a corresponding position for the application of the coating. In particular, the substrate is arranged horizontally, for example, so that a Coating can be applied accordingly along a gravitational direction.

[0021] “Application” describes the physical application of a “coating liquid” to the substrate, whereby a coating liquid can be a liquid, for example, with a viscosity analogous to water or paint, but can also be a gel-like mass. “Liquid” is synonymous with viscous media of different viscosities which are flowable or deformable, in particular with a viscosity below, for example, 100,000 mPa-s. What these possible coating liquids have in common is that they are flowable or spreadable. The result is a “liquid raw layer”, i.e. a layer of the coating liquid, for example analogous to a layer of paint on the substrate.

[0022] It should also be mentioned that the adhesive force on the substrate can be increased before or during application of the coating liquid, for example by applying a primer, by chemically or physically activating the surface of the substrate, and / or by adapting, modifying, or equipping the coating liquid with adhesion-enhancing components. If a primer is used, this primer can also be subjected to its own curing process before the coating liquid is applied.

[0023] “Pre-curing” describes the partial hardening, i.e. chemical and / or physical conversion, of the coating liquid in such a way that the viscosity is greatly increased and, for example, converted into a solid. This involves pre-curing a “surface”, i.e. a portion of the coating liquid facing away from the substrate and towards the environment. This pre-curing is carried out by means of “irradiated pre-curing radiation”, i.e. with appropriately energetic electromagnetic radiation which is suitable and used to carry out the pre-curing. Such pre-curing radiation can be selected from different spectral ranges of the electromagnetic spectrum and can also include visible light, for example. The result is that the surface is then pre-cured, i.e. converted into a higher viscosity state, in particular a solid state.In contrast to the surface, a "supporting layer" which is arranged between the surface and the substrate remains liquid and / or at least merely gelled, whereby "liquid" describes a viscosity which is at least lower than that of the surface. "Gelled" describes a transition from a technically liquid state to a gel-like and / or solid state.

[0024] It has been surprisingly shown that when selecting a suitable coating liquid, the surface is subjected to pre-curing radiation and has a "random microstructuring", i.e. a random and particularly irregular number of Raised areas and depressions are formed, particularly in the microscopic range, so that a correspondingly structured surface with random microstructuring is prepared. In this regard, it should be mentioned that a typical microstructuring produced in this way has, for example, an aspect ratio of 0.1 to 0.4, resulting in, for example, a frequency of around 6 oscillations per 200 pm with correspondingly irregular deviations. This makes it possible to produce structuring in the range from 5 pm to 50 pm, for example around 25 pm or around 35 pm. The amplitude of corresponding microstructurings can be, for example, 1 pm to 5 pm. The result is a fine and finely structured coating with significant glare reduction.

[0025] The "aspect ratio" is a ratio of height to width of corresponding characteristic structural dimensions, in the case of the aspect-reducing coating a ratio of an average height of corresponding topographies to their average width over a measuring range.

[0026] The surface and the base layer then "harden", whereby the hardening describes a transfer of the surface and the base layer to a solid or a viscous medium that has gelled to such an extent that flowing off and / or changing the surface and the base layer is prevented and a permanent state is established. The hardening of the previously liquid raw layer takes place by means of "irradiated curing radiation", i.e. an analogue to the irradiated Pre-curing radiation specifically selected electromagnetic radiation so that the coating is formed from the cured surface and the cured base layer by means of the coating liquid from the raw layer.

[0027] The result is a bend-reducing coating by creating and fixing, in particular curing, the random microstructuring on the Substrate applied.

[0028] In order to carry out the process particularly reliably and as technically simply as possible, a coating liquid which can be hardened with ultraviolet radiation and in particular comprising an acrylate, an acrylate residue, an epoxy residue, an aryl, a vinyl and / or a vinyl residue is applied, so that the pre-hardening and / or curing takes place in particular by means of ultraviolet radiation and / or the pre-hardening and / or curing takes place by means of excimer radiation and / or by means of electron beams and / or by means of infrared radiation. Monomers or oligomers with unsaturated compounds are particularly suitable for this purpose. In addition, the corresponding coating liquid can comprise additives which serve, for example, to set the desired properties of the coating liquid or the bond-reducing coating.

[0029] “Ultraviolet radiation” describes in particular a radiation that is invisible to the human eye. Wavelength range of electromagnetic radiation, whereby the ultraviolet range of the electromagnetic spectrum is described from approximately 380 nm to approximately 100 nm, although corresponding boundary areas can be blurred here. It has been shown that acrylates and / or oligomeric acrylates in particular can be pre-cured and / or cured using ultraviolet radiation. Pre-curing and / or curing can also be carried out by means of “excimer radiation”, whereby such excimer radiation is generated by means of an excimer, acronym for “excited dimer”. This technology is used, for example, in excimer lasers in which short-lived particles in an excited state emit light, whereby light of a particular wavelength is generated here in particular. For example, light with a wavelength of 172 nm can be generated using a xenon excimer emitter, which can be used for pre-curing.

[0030] “Electron radiation” describes a technically generated beam of electrons, whereby, with the appropriate choice of coating fluids, electron radiation can also be used for pre-curing and / or curing.

[0031] In one embodiment, the pre-curing radiation and / or the curing radiation has a wavelength of 100 nm to 300 nm, in particular 150 nm to 250 nm, in particular 172 nm and / or 222 nm.

[0032] In order to produce a structured coating suitable for photovoltaic modules, the Application of the coating liquid with a layer thickness of 3 pm to 100 pm, in particular 5 pm to 35 pm, and / or by means of a roller application, by means of a spray application, by means of screen printing, by means of spraying through a slot nozzle and / or by means of a doctor blade application.

[0033] According to one embodiment of the invention, the coating liquid is applied with a viscosity of 0.4 to 0.8 Pa-s. This viscosity range, in particular, for example, 0.5 Pa-s or even 0.6 Pa-s, ensures that a correspondingly glare-free microstructure of the coating surface is achieved.

[0034] Viscosity describes the property of liquid or gaseous material systems to flow under the influence of mechanical stress and to be irreversibly deformed in the process. The absorbed mechanical stress depends on the deformation rate. A high viscosity describes a low flowability compared to a material system with a low viscosity. Viscosity is generally expressed in Pa-s (Pascal-seconds).

[0035] For example, the mixture of corresponding monomers and oligomers is crucial for the viscosity of the coating fluid. For example, a mixture of aliphatic urethane acrylate with an acrylate functionality of 2 to 4 and a weight fraction of 25 to 40% and an acrylate with an acrylate functionality of 2 and a weight fraction of 28 to 40% if a photoinitiator and nano-silica are also added.

[0036] According to a further embodiment of the invention, the coating liquid comprises a SiO x on , whereby a portion of the SiO x in the coating liquid is 20 to 30 wt .% . With such a proportion of SiO x a corresponding tendency of the coating liquid to form a microfold, i.e. an irregularly wavy and thus glare-free coating, is promoted. The SiO xis particularly available as nanoscale SiO x introduced .

[0037] Silanization of the surface of the SiO x contribute to an increase in SiO x -part, while still maintaining a relatively low viscosity. By such silanization, on the surface of the SiO x -particles (particles) creates a polysiloxane layer, which compensates for surface tensions on SiO x -particles and surrounding organic liquid of the coating liquid.

[0038] The term "SiOx" describes in particular inorganic oxides of silicon, whereby in particular silicon dioxide, also known as quartz, can be used. In particular, pyrolytically produced SiO xbe used, whereby typical grain sizes (particle sizes) of 2 to 100 nm, in particular 10 to 100 nm, are achieved, especially after silanization. Such SiO x - Particles with these grain sizes are generally also called Nanosilica is called .

[0039] Appropriate layer thicknesses ensure the above-described effect of creating a random microstructure particularly reliably. "Roller application" describes application using, for example, a cylindrical roller, so that the substrate can be reliably coated with the coating liquid in a corresponding layer thickness, for example, in a continuous process. Analogously, known processes for coating substrates can be used.

[0040] In a further embodiment, pre-curing takes place in an ambient atmosphere, wherein the temporary viscosity of the coating liquid and / or a frequency of microfolding of the random microstructuring of the surface is adjusted by adjusting the irradiation duration and / or the wavelength of the pre-curing radiation. Likewise, other parameters, such as layer thickness, selection of the coating liquid, and adjustment of the radiation intensity of the pre-curing radiation and / or the curing radiation, can be varied in order to adjust the irradiation-reducing coating accordingly.

[0041] Pre-curing in ambient atmosphere has proven to be particularly reliable for generating random microstructuring, whereby a "irradiation time", i.e. a corresponding time of Irradiation and / or the selection of an appropriate wavelength of the pre-curing radiation can be used to design the random microstructuring as desired. A "temporary viscosity," i.e., the viscosity of the coating fluid that develops during the process, and / or a "microfolding frequency," i.e., a number of surface ridges and valleys within a specific design range, such as a specified measuring distance, are designed accordingly.

[0042] In particular, curing can take place in a protective atmosphere with a higher nitrogen content or a lower oxygen content than the ambient atmosphere. An atmosphere with a higher nitrogen content or another inert or unreactive gas can be used for this purpose, particularly to displace oxygen.

[0043] For example, harmful influences are kept away by the protective atmosphere, with nitrogen proving to be particularly reliable.

[0044] According to a further embodiment, the pre-curing takes place at a pre-curing temperature of 10°C to 50°C, in particular 20°C to 35°C. This temperature range, in particular in combination with the further embodiments, contributes to achieving the microstructuring according to the invention.

[0045] According to one embodiment, cleaning, purifying, and / or preparing the substrate can also be carried out using excimer radiation, particularly in an atmosphere of ambient air. In this case, a provided or even increased oxygen content can contribute to improving the cleaning, purifying, and / or preparing.

[0046] In one embodiment, the field-reducing coating is applied by means of a direct application to a solar cell, a solar glass and / or a solar module or a product or translucent component that encloses, covers and / or protects solar cells and / or solar modules. Examples of applications, each with photovoltaic elements, include: automobile roofs, house facades, electronic devices for handheld operation, bicycle speedometers, mobile energy storage devices with solar power supply and / or mobile data processing devices. An example of a directly coated solar cell is a weight-optimized solar cell for a space application.

[0047] Such a "direct application" refers to the direct application of the coating liquid onto a solar cell, a substrate, the solar glass, the solar film and / or onto the solar module, whereby corresponding intermediate steps for a transfer or bonding of a coating element carrying the microstructuring can be omitted. In this case, the substrate, in particular the solar glass, the solar film and / or the solar module, can already be pretreated with a primer, for example.

[0048] In a further aspect, the object is achieved by a coating liquid for producing a bond-reducing coating on a substrate, in particular by means of a method according to one of the previously described embodiments, wherein the coating liquid comprises an acrylate, an acrylate residue, an epoxy residue, an aryl, a vinyl and / or a vinyl residue and a viscosity of 0.4 to 0.8 Pa -s.

[0049] It should be noted that conventional oligomeric acrylate binders have a relatively high viscosity of >0.8 Pa-s, for example, 10 to 10,000 Pa-s. The desired viscosity is achieved by adding another component, in particular a low-viscosity reactive diluent (for example, HDDA = hexanediol diacrylate).

[0050] According to one embodiment, an acrylate present in the coating liquid is a 1,6-hexanediol diacrylate, in particular with a concentration of 10 to 30 wt.%. This ensures high weathering stability in the saturation-reducing coating.

[0051] The "weathering stability" refers in particular to the stability of the weather-reducing coating against abrasion, yellowing or becoming milky, whereby corresponding negative effects are caused in particular by light, more specifically by UV light when exposed to sunlight. A high Weathering stability refers to long-term resistance to corresponding negative influences.

[0052] According to one embodiment, the coating liquid has a SiO x -Concentration of 20 to 45 wt.%, in particular 20 to 30 or 30 to 40 or 30 to 45 wt.%.

[0053] By means of the method according to the invention according to one or more of the previously described embodiments, in particular a bend-reducing coating is produced which has a profile with an amplitude of 3-10 pm, an aspect ratio between 0.1 and 0.2 and / or frequencies of 6 to 8 oscillations per 200 pm measuring section.

[0054] In a further aspect, the object is achieved by a substrate, in particular a solar glass or a solar film with a coating having an irregular microstructure, wherein the coating is produced by a method according to the previously described embodiments and / or by means of a coating liquid according to one of the previously described embodiments.

[0055] A "solar glass", which can in particular form a cover glass of a photovoltaic module, is made, for example, from corresponding glasses usable for photovoltaic modules, whereby solar glass is optimized to transmit certain wavelength ranges necessary for solar yield or with regard to another optical property. A "solar film", as described above, is a flexible and / or moldable cover made, for example, from a plastic. which is usually flat and thin compared to its surface area. Solar glass or solar film can also be optimized for mechanical strength, for economic reasons, or for abrasion resistance.

[0056] In a further aspect, the object is achieved by a solar cell and / or a solar module, wherein the solar cell and / or the solar module has or has a solar glass and / or a solar film according to the previously described embodiment and / or the solar cell has or has a field-reducing coating according to the invention.

[0057] In a further aspect, the object is achieved by a solar system with a plurality of solar cells and / or a plurality of solar modules according to the previously described embodiment. Such a solar system can utilize the microstructuring according to the invention, in particular the field-reducing coating according to the invention with the random microstructuring, to generate particularly high solar yields.

[0058] The invention will be explained in more detail below using exemplary embodiments. Figure 1 shows a coating process for coating a substrate for solar applications, Figure 2 shows a surface scan of a structured Surface of the coating of Figure 1 with a diagram, Figure 3 shows a diagram with a function for Reflection of incident light onto the coating of Figure 1 , as well as Figure 4 shows a PV element with a cover having a coating with a structure.

[0059] A coating process 101 serves to coat a substrate 103. The substrate 103 can be a thin glass layer, but the substrate 103 can also be formed by a film or another suitable, particularly translucent, surface. In the example described here, a substrate made of thin solar glass is assumed. Such solar glass has a particularly high transmittance for light wavelengths that can be converted into electrical current by a solar cell.

[0060] By means of a roller 105, in an application area 106 a coating liquid 131 is rolled onto the substrate 103 with a defined layer thickness. The layer thickness is approximately 25 pm. The coating liquid 131 is an acrylate and has a varnish-like viscosity. It should be mentioned that the substrate 103 is moved along a conveying movement 181 in a continuous process, i.e. is also guided under the roller 105. In a subsequent application area along the conveying movement Pretreatment area 107 can then be used for pretreatment and / or evaporation of the coating liquid 131. Likewise, for example, targeted aeration, smoothing and / or conditioning of the coating liquid 131 in this pretreatment area 107.

[0061] In this pretreatment area 107, the coating liquid 131 is arranged as a liquid layer 133 on the substrate 103. Along the conveying movement 181, the substrate 103 with the liquid layer 133 then passes through a surface hardening zone 123, in which radiation is introduced onto the liquid layer 133 by means of a surface hardener 109. This is excimer radiation with a wavelength of 172 nm. An appropriate atmosphere, for example by means of purified air, can be set within a pre-hardening volume 153 located between the surface hardener 109 and the liquid layer 133. The liquid layer 133 then forms a surface 135 and a support layer 137, wherein the surface 135 is oriented in the direction of the surface hardener 109, whereas the support layer 137 forms the contact in the direction of the substrate 103.The support layer 137 remains liquid, i.e., similar to the liquid layer 133, whereas the surface 135 undergoes an initial hardening by the excimer radiation through the surface hardening 109. The surface 135 forms a random microstructure, the geometry of which is pre-fixed, for example gelled, by the surface hardening 109 and is received in a floating manner on the support layer 137. If the substrate 103 is then conveyed further along the conveying movement 181 into a through-curing zone 125, the surface 135 and the support layer 137 are bonded together by means of a... Through-curing 111 is irradiated, wherein a through-curing volume arranged between the through-curing 111 and the substrate 103 can be equipped, for example, with a nitrogen atmosphere in order to keep atmospheric oxygen away from the surface 135. In this area, the surface 135 and the support layer 137 are cured to form the finished layer 139, wherein the microstructuring of the surface 135 is also fixed. The result is a coating 141 on the substrate 103, wherein a random microstructuring is applied to the coating 141.

[0062] A surface scan 201 shows this microstructuring on the coating 141 in the form of a height profile. This shows peak areas 203 and valley areas 207 which form the microstructure 207. It should be mentioned again in this regard that the microstructure 207 is randomly geometrically shaped, i.e. for example, by means of an intensity of the surface hardening 109, corresponding mean frequencies and / or wavelengths as well as corresponding amplitudes can be set, but in particular no geometrically repeating or uniform structures are created. A diagram 221 has an abscissa 223 and an ordinate 225, wherein the abscissa 223 and the ordinate 225 correspond to corresponding X / Y directions of the microstructure 207 of the surface scan 201. A height function 227 maps the corresponding height profile around a mean value 229 along a reference line, whereby the mean value 229 is "0" here.As can be seen in Figure 2, the height function 227 is random and has. different local wavelengths, different amplitudes and valley depths.

[0063] A diagram 301 has an abscissa 303 and an ordinate 305, wherein the abscissa 303 denotes an angle of incidence of light onto the surface of the coating 141, measured from 0° to 90°, and the ordinate 305 denotes a corresponding luminance in [cd / m 2 ] A function 307 shows the corresponding luminance as a function of the angle of incidence.

[0064] A PV element 401 has a solar module 403. A solar cell 405 is embedded within the solar module 403, wherein electrical power generated by the solar cell 405 can be dissipated via connecting cables 407. A cover 409 is applied in the direction of the incoming sunlight 421, wherein the cover comprises the substrate 103 with the coating 141 having the microstructure 207. By means of the microstructure, the reflection of the incoming sunlight 421 is significantly minimized, so that more effective radiation reaches the solar cell 405, thus correspondingly increasing the electrical yield and / or avoiding unpleasant, harmful, or legally prohibited glare. Reference symbol list 101 Coating Processes 103 Substrat 105 whales 106 Order area 107 Pretreatment area 109 Surface hardening 111 Curing 121 Pre-curing zone 123 Surface hardness zone 125 hardening zone 131 Coating liquid 133 Liquid layer 135 Surface 137 base layer 139 Finished shift 141 Coating 153 pre-curing volume 155 curing volume 181 Conveyor movement 201 Area scan 203 high areas 205 valley areas 207 Microstructure 221 Diagram 223 Abs zisse 225 Ordinate 227 Height function 229 mean 301 Diagram 303 Abs zisse 305 Ordinate 307 Function 401 PV element 403 solar module 405 solar cell 407 Connection cable 409 Cover 421 Sunlight

Claims

Patent claims:

1. A method (101) for applying a field-reducing coating (141) to a substrate (103), in particular to a solar glass and / or to a solar film, wherein a structured coating (141) for refracting and / or scattering incident light (421) is applied to the substrate (103), comprising the following steps: - providing the substrate (103) so that the substrate (103) is available for applying the coating (141), - applying (106) a coating liquid (131) to the substrate (103) so that a liquid raw layer (133) is produced on the substrate (103), - pre-curing (109) a surface (135) of the coating liquid (133) by means of pre-curing radiation radiated onto the surface (135) with a pre-curing dose of at least 60 mJ / cm 2, so that the surface (135) is pre-cured and a support layer (137) arranged between the surface (135) and the substrate (103) is still liquid and / or at least only gelled and the surface (135) is cured by irradiating the pre-curing radiation with the pre-curing dose of at least 60 mJ / cm 2 a random microstructuring (201) is formed, - Curing (111) of the surface (135) and the base layer (137) by means of curing radiation radiated onto the previously liquid raw layer (133), so that the coating (139, 141) is formed from the cured surface (135) and the cured base layer (137) by means of the coating liquid (131) from the raw layer (133), so that a bend-reducing coating (141) on the substrate (103) is applied.

2. Method according to claim 1, characterized in that the application (106) of a coating liquid (131) which can be cured with ultraviolet radiation, in particular comprising an acrylate, an acrylate residue, an epoxy residue, an aryl, a vinyl and / or a vinyl residue, takes place, so that the pre-curing (109) and / or the curing (111) takes place in particular by means of ultraviolet radiation and / or that the pre-curing (109) and / or curing (111) takes place by means of excimer radiation and / or by means of electron radiation and / or by means of infrared radiation.

3. Method according to claim 1 or 2, characterized in that the pre-curing radiation and / or the curing radiation has a wavelength of 100nm to 300nm, in particular 150nm to 250nm, in particular 172nm and / or 222nm.

4. Method according to one of the preceding claims, characterized in that the application (106) of the coating liquid (131) takes place with a layer thickness of 3pm to 100pm, in particular 5pm to 35pm, and / or by means of a roller application (105, 106).

5. Method according to one of the preceding claims, characterized in that the application (106) of the coating liquid (131) takes place with a viscosity of the coating liquid of 0.4 to 0.8 Pa -s.

6. Method according to one of the preceding claims, characterized in that the coating liquid (131) comprises a SiOx, wherein a portion of the SiO x in the Coating liquid (131) is 20 to 30 wt.%. I. Method according to one of the preceding claims, characterized in that the pre-curing (109) is carried out in an ambient atmosphere (153) and / or under a Inert gas atmosphere, wherein by adjusting an irradiation duration and / or a wavelength of the pre-curing radiation, the in particular temporary viscosity of the coating liquid (131) and / or a frequency of a microfolding of the random microstructuring (201) of the surface (135) is adjusted.

8. Method according to one of the preceding claims, characterized in that the pre-curing is carried out at a pre-curing temperature of 10°C to 50°C, in particular 20°C to 35°C.

9. Method according to one of the preceding claims, characterized in that the curing (111) takes place under a nitrogen atmosphere (155) or under a protective atmosphere (155) having a nitrogen content increased compared to the ambient atmosphere.

10. Method according to one of the preceding claims, characterized in that the application (106) of the field-reducing coating (141) is carried out by means of a direct application on a solar glass and / or on a solar module. II. Coating liquid for producing a bond-reducing coating on a substrate, in particular by means of a method according to one of the preceding claims, characterized in that the coating liquid comprises an acrylate, an acrylate residue, an epoxy residue, an aryl, a vinyl and / or a vinyl residue and a viscosity of 0.4 to 0.8 Pa -s.

12. Coating liquid according to claim 11, characterized in that in the coating liquid acrylate present is a 1,6-hexanediol diacrylate, in particular with a concentration of 10 to 30 wt.%.

13. Coating liquid according to claim 11 or 12, characterized by a SiO x-Concentration of 20 to 45 wt%, in particular 30 to 40 wt%.

14. Solar glass (409) or solar film with a coating (141) with an irregular microstructure (201), wherein the coating (141) is applied by a method according to one of the preceding claims 1 to 10, and / or by means of a Coating liquid prepared according to one of the preceding claims 11 or 13.

15. Solar cell (403) and / or solar module (401), wherein the solar cell (403) and / or the solar module (401) comprises or comprises a solar glass (409) or a solar film according to claim 14.

16. Solar system with several solar cells (403) and / or several solar cells and / or solar modules (401) according to Claim 15.

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