DE102011077126A1 - Photovoltaic arrangement for use as integrated building facade element in building integrated photovoltaic system, has optical filter provided with reflective layer that is located on transparent substrate and provided with set of recesses - Google Patents

Abstract

The arrangement (1) has a solar cell (20) optically coupled with an optical filter (30) i.e. neutral density filter, where the filter includes a reflective layer that is located on a transparent substrate (10). The reflective layer is provided with a set of recesses such that interaction between the optical filter and an incident light radiation causes weakening of the light radiation in a predetermined wavelength range. The filter includes an absorption protecting layer with a set of recesses that correspond to the recesses of the reflective layer. An independent claim is also included for a method for manufacturing a photovoltaic arrangement.

Description

The invention relates to a photovoltaic device having an optical filter, and this filter and a method for producing the device or the filter.

State of the art

Solar energy is a renewable, natural and widely available source of energy, the use of which has increased dramatically in recent years. The photovoltaic (PV) energy conversion takes place with the help of solar cells, which are connected to so-called solar modules, in photovoltaic systems. The generated electricity can either be used locally, stored in accumulators or fed into electricity grids. Photovoltaic systems find their use to be built in a variety of ways, such. B. on building roofs, as facades or as outdoor facilities.

The uninterrupted development and multiple use of photovoltaic systems has inspired entrepreneurs and architects to integrate photovoltaics into buildings in terms of shapes, colors, variance in transparency and various sizes of PV systems. Building Integrated Photovoltaic (GiPV), often called BiPV (Building Integrated Photovoltaic) stands for the integration of photovoltaic solutions in the building envelope, not only the classic energy generation, but also other functions are desired. The GiPV systems are PV elements that are integrated in buildings as components and traditional building materials such. As glazings, roof tiles, metal or marble facades of a building or shutters replace.

This saves money and natural resources. In fact, unlike traditional PV systems, the GiPV systems have two major advantages, namely that energy is generated where it is consumed and energy losses are reduced because it does not have to be transported over a long distance. In addition, these systems not only produce electricity, but also take over the function of components, such as roof tiles or facade parts.

For example, in order to drastically increase the area that can be used to generate energy, transparent solar cells can be installed on windows and facades. Seen from the outside, these cells act as sun protection. Furthermore, they allow an unobstructed view from the outside to the outside, while the interior is not visible from the outside.

However, the physical properties of the materials used for the transparent components cause the passing sun light to be absorbed at certain wavelengths of the spectral range. Most solar cells are made of silicon. A silicon layer usually absorbs the short wavelengths of the light spectrum. It follows that only the longer wavelengths of the spectrum are passed on and that the transmitted light has an orange or red tone. This leads to a change in the inner shade or to a color distortion inside.

To reduce the effect of interior shade change is off US 2009/0165849 A1 an optical filter is known, which is coupled to the transparent solar cell and suitable for adjusting the color properties of the transmission spectrum of the solar cell. This filter limits the CIE standard colors of the transmission spectrum of the solar cell within a certain range and adjusts the color rendering index as well as the color temperature of the transmission spectrum.

Usually, such filters by a coating method, such. Chemical / physical vapor deposition, in which one or more layers of a reflective or absorptive material are mounted on a transparent optical glass. These processes require complicated and expensive equipment. In addition, they do not always deliver completely uniform homogeneous coatings, so that some areas of the filter surface have a thicker or a thinner layer of material. It follows that the filter can act locally in different ways. In addition, such coated arrangements run the risk of degrading the layer quality over time, and the filter loses its own optimum transmission properties.

Disclosure of the invention

The invention provides an arrangement with the features of claim 1, a filter with the features of claim 6 and a manufacturing method with the features of claim 9 ready. Advantageous further developments of the inventive concept are the subject of the respective dependent claims.

The invention includes the basic idea of providing a photovoltaic device having at least one solar cell having an optical filter coupled to the solar cell, the optical filter having a transparent substrate and a reflective layer disposed on the substrate, and the reflective layer having a plurality of Recesses is provided. These recesses are designed and arranged such that the interaction between the optical filter and an incident light radiation causes a weakening of the light radiation in a predetermined wavelength range.

This PV array may correspond to a transparent photovoltaic module used as a GiPV system or as part of a building, the solar cell made of transparent material having a transparent substrate of glass or plastic and the optical filter having the back side Surface of the solar cell to be connected.

Here, the optical filter is positioned on the side of the PV array facing the building interior. A transparent substrate, an optical filter and at least one (transparent) solar cell in this case correspond to the basic elements of a transparent PV module.

Of course, additional elements such. B. additional solar cells, insulation layers, protective layers, antireflection layers u. s. w., to be used.

When the light is incident on the solar cell, a certain part of the radiation is used or absorbed for conversion into electrical energy. The rest of the radiation then reaches the filter. In this case, the interaction between the light and the recesses and the absorption capacity of the material of the reflection layer allow part of the transmitted radiation to be partially reflected back by the presence of the recesses and absorbed by the solar cell so that a different part of the radiation is directly absorbed by the filter and that a last part of the radiation reaches the interior of the building.

The effect of the filter is determined by the arrangement and the design of the recesses. The interaction between the incident light and the reflection layer or the recesses of the reflection layer, in particular, enables a uniform weakening of a specific wavelength range of the light. Thus, an alternative solution for eliminating the internal color corruption of a PV array is shown, which allows a more accurate selection of the wavelength range over the known solutions and uses an optical filter which, unlike the known coated optical filters, is more durable and efficient.

It should be emphasized that both the design (the width, the depth and possibly the shape) and the number of recesses allows a change in the transmittance of the filter. Thus, the transmittance can be increased by increasing the notch width and / or by the number of notches.

The transparent substrate of the optical filter can in this case be a highly transparent optical glass, in particular float glass, but also Plexiglas. The reflective layer may comprise a metal or an oxide with a metal, in particular a transparent conductive oxide.

In one embodiment, the filter of the PV array is configured as a neutral density filter to allow a constant (attenuated) light transmission in a particular radiation area. In particular, the filter can operate in the range between 300 nm and 1400 nm, preferably between 350 nm and 1300 nm, preferably between 400 nm and 1200 nm. Here, the transmission of the visible spectrum and the near-infrared radiation is ensured by the filter.

In another embodiment, the filter of the PV array further comprises an anti-absorption layer, the anti-absorption layer being provided with a plurality of recesses corresponding to the recesses of the reflective layer. By absorption-protective layer is meant a layer which can have an optical function for the transmission of only certain spectral components of the radiation and serves as a process auxiliary layer for the clean and efficient structuring of the reflection layer. The absorption protective layer may be disposed either between the substrate and the reflective layer or on the reflective layer.

The absorption protective layer may include a semiconductor layer such as amorphous silicon, polycrystalline silicon, microcrystalline silicon or silicon germanium. Alternatively, the Hableiterschicht a material such. Copper indium gallium selenium (CIGS) in any stoichiometric composition containing no silicon. Depending on the absorbent material used, the wavelength range of the filtering action can be adjusted as needed.

In a further embodiment, the recesses are designed as trenches, which are arranged side by side. Depending on the desired transmissivity of the filter, the depth of the recesses may be deeper or less deep. In particular, the recesses can reach all the way to the substrate. To create a grid structure, the recesses may be designed as intersecting trenches.

Alternatively or additionally, point-like recesses may be provided. These can be arranged regularly or irregularly.

As explained above, the design of the recesses plays an essential role in defining the transmission characteristics of the filter. In embodiments, the recesses may be designed such that the recess width between 3 .mu.m and 300 .mu.m, preferably between 5 .mu.m and 250 .mu.m, preferably between 10 .mu.m and 200 .mu.m and the recess spacing between 3 .mu.m and 1100 .mu.m, preferably between 5 .mu.m and 1050 μm, preferably between 10 μm and 1000 μm.

The invention further includes the idea of providing an optical filter comprising a transparent substrate and a reflective layer disposed on the substrate, the reflective layer being provided with a plurality of recesses which are designed and arranged such that the interaction between the optical system and the optical system Filter and incident light radiation allows selection of the light radiation to specific wavelengths.

This filter can be used in different fields. In particular, it may be used in conjunction with other devices or as a separate element. Embodiments of this filter largely correspond to the above-described embodiments of the photovoltaic device, insofar as they relate to their filter component.

Specifically, the filter may be formed as a neutral density filter to allow a constant light transmission with respect to the wavelength of a particular radiation area. In particular, the filter can operate in the range between 300 nm and 1400 nm, preferably between 350 nm and 1300 nm, more preferably between 400 nm and 1200 nm.

In order to change the absorption properties of the filter or to improve the structuring of the reflection layer, the filter may in particular have an absorption protective layer, wherein the absorption protection layer is provided with a plurality of recesses which correspond to the recesses of the reflection layer.

The inventive method comprises arranging a reflection layer on a surface of a transparent substrate and generating a plurality of recesses in the reflection layer, in particular by a laser.

In another embodiment, the method comprises disposing an anti-absorption layer on a surface of a transparent substrate, disposing a reflective layer on the anti-absorption layer, and forming a plurality of recesses in the reflective layer and in the anti-absorption layer, particularly by a laser ,

Alternatively, the method includes disposing the reflective layer on the substrate, disposing an anti-absorption layer on the reflective layer, and forming a plurality of recesses in the anti-absorption layer and the reflective layer, particularly by a laser.

By using a laser, the recesses can be made with great precision. Thus, the filter achieves a precisely tuned transmission capability.

It should be noted here that the heating during the lasering can lead to a melt of the metal present in the reflection layer. Therefore, the absorption protective layer or the semiconductor layer and / or the oxide layer in the reflection layer can serve as absorption elements for the laser in order to avoid metal contamination of the glass substrate.

In a further embodiment, the recesses are preferably formed by a pulse laser, more specifically by an Nd: YAG pulse laser, having a wavelength between 266 nm and 1064 nm. In particular, a wavelength of 355 nm or 1064 nm, and a pulse duration, becomes shorter than 100 ns and longer than 500 ps.

In one embodiment, where the filter does not have an anti-absorption layer and the reflective layer is made of a metal, the recesses are made by the laser having a wavelength of 355 nm and a pulse duration shorter than 100 ns and longer than 500 ps ,

In an embodiment where the filter still does not have an anti-absorption layer, but the reflective layer is made of a metal and an oxide, the recesses are made by the laser having a wavelength of 355 nm or 1064 nm and a pulse duration shorter than 100 ns and longer than 500 ps.

On the other hand, if the filter has an anti-absorption layer, the recesses are made by the laser having a wavelength between 355 nm and 1064 nm and a pulse duration shorter than 100 ns and longer than 500 ps.

Drawings:

Incidentally, advantages and expediencies of the invention will become apparent from the following description of selected exemplary embodiments with reference to the figures. From these show:

1 a schematic representation of a PV array according to an embodiment of the invention, and

2a to 2c schematic representations of an optical filter according to three embodiments of the invention.

1 shows a schematic diagram of a PV array 1 which is a substrate 10 made of glass, one with the substrate 10 coupled transparent solar cell 20 and one with the back of the solar cell 20 coupled optical filter 30 having. The solar cell 20 includes first and second electrodes and a photoelectric conversion layer (not shown) disposed between the electrodes. Furthermore, between the solar cell 20 and the filter 30 an insulation layer 21 arranged to the electrode of the solar cell 20 from the filter 30 to isolate. This PV arrangement 1 is to be regarded as building-integrated facade element, whereby the filter 30 the inside and the substrate 10 with a surface 11 correspond to the outside of the facade element.

The on the substrate surface 11 incident solar radiation is from the glass substrate 10 pass through. For converting the sunlight into electrical energy, the solar cell absorbs a certain portion of the radiation, which is dependent on the material of the photoelectric conversion layer. The rest of the radiation then reaches the filter 30 so the hue is on the inside 31 the filter incident light is adjusted in a certain wavelength ranges. Here the filter works 30 as a neutral density filter in the range between 400 nm and 1200 nm.

2a shows an optical filter 30 ' which is a highly transparent optical glass 32 and one on the glass 32 arranged reflection layer 33 having. The reflection layer 33 is here with a variety of recesses 34 provided, which up to the surface of the substrate 32 pass. The on the filter 30 ' incident solar radiation is partly due to the reflection layer 33 reflected and partly through the recesses 34 forwarded. The design of the recesses 34 (For example, their width) and the material of the reflection layer allow both a selection of certain wavelengths as well as a change in the transmittance of the filter 30 ' ,

2 B shows an alternative optical filter 30 '' which is a highly transparent optical glass 32 , one on the glass 32 arranged absorption protective layer 35 and one on the absorption protective layer 35 arranged reflection layer 33 having. Both absorption protection layer 35 and the reflective layer 33 are with a variety of recesses 34 . 36 provided, with the recesses 36 the absorption protective layer 35 with the recesses 34 the reflection layer 33 correspond. The on the filter 30 '' incident solar radiation is partly due to the reflection layer 33 reflected or through the absorption protective layer 35 absorbed and partly through the recesses 34 and 36 forwarded. The design of the recesses 34 and 36 (For example, the recess width), as well as the material of the reflection layer and the absorption-protective layer, allow both a selection of certain wavelengths as well as a change in the transmittance of the filter 30 '' ,

2c shows a still alternative optical filter 30 ''' which is a highly transparent optical glass 32 , one on the glass 32 arranged reflection layer 33 and one on the reflective layer 33 arranged absorption protective layer 35 having. As in the filter 30 '' of the 2 B , are both absorption-protective layer 35 and the reflective layer 33 with a variety of recesses 34 . 36 provided, with the recesses 36 the absorption protective layer 35 with the recesses 34 the reflection layer 33 correspond. The on the filter 30 ''' incident solar radiation is partly due to the absorption protective layer 35 absorbed or through the reflective layer 33 reflected and partly through the recesses 34 and 36 forwarded. The design of the recesses 34 and 36 (For example, the recess width), as well as the material of the reflection layer and the absorption protective layer, allow both a selection of certain wavelengths as well as a change in the transmittance of the filter 30 ''' ,

The embodiment of the invention is not limited to the examples and highlighted aspects described above, but also possible in a variety of modifications, which lies within the scope of technical action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2009/0165849 A1 [0007]

Claims (10)

Photovoltaic arrangement ( 1 ) with a solar cell ( 20 ) and one with the solar cell ( 20 ) optically coupled optical filter ( 30 ; 30 ' ), which is a transparent substrate ( 32 ) and one on the substrate ( 32 ) arranged reflection layer ( 33 ), wherein the reflection layer ( 33 ) with a plurality of recesses ( 34 ), which are designed and arranged such that the interaction between the optical filter ( 30 ; 30 ' ) and an incident light radiation causes a weakening of the light radiation in a predetermined wavelength range. Arrangement according to claim 1, wherein the filter ( 30 ; 30 ''; 30 ''' ) an absorption protective layer ( 35 ), wherein the absorption protective layer ( 35 ) with a plurality of recesses ( 36 ), which leads to the recesses ( 34 ) of the reflection layer ( 33 ) correspond. Arrangement according to claim 1 or 2, wherein the filter ( 30 ; 30 '; 30 ''; 30 '' ) in the range between 300 nm and 1400 nm, in particular between 350 nm and 1300 nm, more particularly between 400 nm and 1200 nm, acts as a neutral density filter. Arrangement according to one of the preceding claims, wherein as recesses ( 34 . 36 ) intersecting trenches and / or point-like recesses are provided, which are arranged in particular regularly. Arrangement according to one of the preceding claims, wherein the recesses ( 34 . 36 ) have a lateral dimension between 10 microns and 200 microns and a distance between 10 microns and 1000 microns. Optical filter ( 30 ; 30 ' ) comprising: a transparent substrate ( 32 ) and one on the substrate ( 32 ) arranged reflection layer ( 33 ), wherein the reflection layer ( 33 ) with a plurality of recesses ( 34 ), which are designed and arranged such that the interaction between the optical filter ( 30 ; 30 ' ) and an incident light radiation causes a weakening of the light radiation in a predetermined wavelength range. The filter of claim 6, further comprising: an absorbent protective layer ( 35 ), wherein the absorption protective layer ( 35 ) with a plurality of recesses ( 36 ), which leads to the recesses ( 34 ) of the reflection layer ( 33 ) correspond. Filter according to claim 6 or 7, wherein the filter ( 30 ; 30 '; 30 ''; 30 ''' ) in the range between 300 nm and 1400 nm, in particular between 350 nm and 1300 nm, more particularly between 400 nm and 1200 nm, acts as a neutral density filter. Method for producing a photovoltaic arrangement according to one of Claims 1 to 5 or an optical filter ( 30 ; 30 ' ) according to one of claims 6 to 8, comprising the steps: - arranging the reflection layer ( 33 ) on a surface of the transparent substrate ( 32 ); and - generating the plurality of recesses ( 34 ) in the reflection layer ( 33 by laser radiation having a wavelength between 266 nm and 1064 nm, in particular 355 nm or 1064 nm, and a pulse duration shorter than 100 ns and longer than 500 ps. Method according to claim 9, comprising arranging the absorption protective layer ( 35 ) on the reflection layer ( 33 ) or arranging the absorption protective layer ( 35 ) on a surface of the transparent substrate ( 32 ) and arranging the reflection layer ( 33 ) on the absorption protective layer ( 35 ).

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