DE102021127793A1 - Power dissipation system for a shading device and shading device therefor - Google Patents

Abstract

The invention relates to a current removal system for a shading device, at least with a large number of slats (7) with photovoltaic elements (7a) for generating electricity, there being at least one busbar (4) which runs through the slats (7) and connects them to one another in an electrically conductive manner , in order to dissipate the electricity generated in the photovoltaic elements (7a). The invention also relates to a shading device with a large number of slats (7) with photovoltaic elements (7a) for generating electricity, with a current discharge system according to the invention being present for dissipating the generated electricity.

Description

The invention relates to a power dissipation system for a shading device, at least with a large number of slats with photovoltaic elements for generating electricity, and a shading device with a power dissipation system.

External venetian blinds with slats on which photovoltaic elements (also called photovoltaic cells) are applied are already known from the prior art. For this purpose, for example, reference is made to the publications DE 10 2007 031 236 A1 or DE 10 2014 200 359 A1 referred.

Furthermore, it is from the pamphlet DE 21 2019 000 358 U1 known to connect the slats by means of a conductor wire for current dissipation. However, this conductor wire is visually unattractive and has a negative effect on the handling and functionality of the external venetian blind.

It is therefore the object of the invention to provide an alternative current discharge for a shading device with photovoltaic slats and a shading device for this.

This object is solved by the features of the independent patent claims. Advantageous developments of the invention are the subject matter of subordinate claims.

The inventors have recognized that there is an alternative possibility of dissipating the electrical energy generated in the photovoltaic elements on the movable slats of an external venetian blind or a blind to a power grid or power storage device and of avoiding the disadvantages of the prior art.

The invention therefore describes the possibility of dissipating current via an electrically conductive rod, strip or flat rod which runs through the cutouts in the slats, with electrically conductive sliding contacts being present in the cutouts and being electrically connected to the photovoltaic elements. Complex wiring of the individual slats is therefore no longer necessary.

Different photovoltaic elements can be used on the slats. The different concepts for the photovoltaic slats can be divided according to the different technologies of the photovoltaic elements used. First generation photovoltaic elements (wafer-based photovoltaic elements) and second generation photovoltaic elements are characterized by not exceeding the Shockley-Queisser (SQ) limit for single band section devices. Third-generation photovoltaic elements, on the other hand, have an efficiency potential above the SQ limit. The SQ limit describes the maximum achievable conversion efficiency of solar energy for a specific material. The frontier is the benchmark against which new photovoltaic technologies are compared. A certain material has a certain band gap, which is responsible for the fact that only certain spectrums of light can be absorbed. The remaining spectra cannot be absorbed and therefore cannot be used to convert them into electricity (first and second generation photovoltaic elements). Photovoltaic elements of the third generation circumvent this fact, for example with so-called tandem photovoltaic elements, in which several materials are used in different layers in order to be able to also absorb the remaining spectrum of the light and convert it into electricity.

First-generation conventional photovoltaic elements: First-generation photovoltaic elements, i.e. wafer-based photovoltaic elements, are used here. This technology is advantageous because, due to many years of research and its large market share, it has a particularly high degree of long-term testing and a very good price-performance ratio as well as a very high efficiency. A major disadvantage, however, is that mass-produced photovoltaic modules using this technology are only available in sizes that cannot be applied to the slats. Therefore, slats equipped with conventional photovoltaic elements must be manufactured in such a way that the photovoltaic elements are connected and laminated to form a module on the raw slats themselves. Since individual standard photovoltaic elements are too large for the slats, these have to be cut through.

Photovoltaic elements of the second and third generation: These photovoltaic elements have the advantage that they can be manufactured in almost any size with significantly fewer modifications of the manufacturing process, partly due to other manufacturing processes. As a result, the existing surface of the slat can be used without free spaces and thus more efficiently. On the other hand, a decisive disadvantage is that, based on the current state of the art, photovoltaic elements of the second and third generation often cannot compete with the photovoltaic elements of the first generation in terms of their efficiency. Some manufacturing processes allow the photovoltaic cell layer, which is a thin film, to be vapour-deposited directly onto the lamellae, which then act as a substrate. It may be beneficial to coat the slats in advance so that they are more suitable properties for their role as a substrate. The methods used during the manufacturing process include thermal evaporation, sputter deposition, laser deposition and metal-organic vapor phase epitaxy.

• Hier werden ebenfalls Photovoltaikelemente der zweiten und dritten Generation verwendet, die allerdings nicht auf der Lamelle selbst, sondern auf einer Folie hergestellt und anschließend auf die Lamellen aufgeklebt werden. Dieses Konzept bringt den entscheidenden Vorteil mit sich, dass eine räumliche Trennung zwischen der Produktion der Lamellen und der Produktion der Photovoltaikelemente möglich ist. Die Photovoltaikfolie kann als Meterware hergestellt und in der korrekten Breite vorgelagert und passend zugeschnitten werden.

Adhesive photovoltaic elements of the second and third generation:

• Photovoltaic elements of the second and third generation are also used here, although they are not produced on the slat itself, but on a foil and then glued to the slats. This concept has the decisive advantage that a spatial separation between the production of the slats and the production of the photovoltaic elements is possible. The photovoltaic foil can be manufactured by the meter and pre-stored in the correct width and cut to size.

In addition, different slats can also be used. Positive effects can result from the use of lamellas that are less curved in the application area of the photovoltaic elements, for example flat lamellas. On the one hand, the photovoltaic elements only have to adapt to a less pronounced bend, which simplifies the production process and reduces the demands on the photovoltaic elements themselves. On the other hand, the photovoltaic elements can be protected more easily from external influences. It is crucial that the encapsulation of the photovoltaic cell layer adheres sufficiently strongly and reliably to the edges of the slats so that it can develop its encapsulating effect. Since expansion or contraction of the lamellae can cause detachment at weak points such as the edges, it makes sense to take special precautions here. For example, the encapsulation can be wrapped around one or more outer edges of the lamellae, so that the film can also adhere to the underside of the lamellae. Since the flat lamella has no flanging on the outer edges, the film can be folded over without any problems. In the case of a lamella with a beaded edge, the film would not be able to be turned over and laminated without problems and the package height would continue to increase, since the film would reach over the bead and thus further thicken the thickest part of the lamella. The film can then be attached particularly strongly to the underside by other possible methods such as gluing.

Accordingly, the inventors propose a power dissipation system for a shading device, in particular an external venetian blind or a blind, at least with a large number of slats with photovoltaic elements for generating electricity, with at least one busbar being present which runs through the slats and connects them to one another in an electrically conductive manner in order to dissipate the electricity generated in the photovoltaic elements.

The power dissipation system according to the invention serves to feed the power generated in the photovoltaic elements of the slats into a power grid or a power storage device. Depending on the design of the current removal system, an inverter is also advantageously provided. The shading device is preferably a venetian blind or a blind, in particular a blind canopy. The invention is described below using a shading device designed as an external venetian blind.

As with conventional external venetian blinds, the slats of the external venetian blind are movably mounted in lateral guide rails by means of guide bolts attached to the short longitudinal ends. When raising and lowering or tilting the slats, the guide pins move in the guide rails. Furthermore, the shading device, in particular the external venetian blind, has at least one tension element for moving the slats. Advantageously, there are two traction elements in the form of traction cables, cords or straps, which are preferably arranged in the area of the two longitudinal ends of the slats. The slats can be moved up and down and tilted around their longitudinal axis using the drawstrings.

The current discharge via busbars running through the slats can of course be combined with other ways of discharging the current generated in the photovoltaic elements, for example by means of busbars in the guide rails.

In a preferred embodiment with busbars arranged exclusively according to the invention, at least two busbars running through the laminations are formed.

Exactly two busbars, which are electrically connected to the photovoltaic elements, preferably run through each lamella. However, it is also possible for more busbars to run through the laminations, in which case there is not an electrical connection to every lamina. As a result, different types of series connection of the slats to increase the voltage are possible. For example, a busbar is alternately electrically connected to the slats, or the slats are opposite the busbar isolated. According to the invention, however, the busbars run through all the laminations, even if there is not an electrical contact with each lamina. In an embodiment with two busbars, these are advantageously at the same potential.

In principle, it is also possible for more than one busbar to run through a recess and for the individual busbars to be contacted differently and, for example, also to be at different potentials.

The busbars are advantageously connected to a power grid or power storage unit at the lower and upper ends.

The busbars are preferably designed to be stationary. In order to enable the busbars to run through the lamellae, in a particularly favorable embodiment the lamellae each have recesses or openings or holes through which the busbars are guided. In this case, either electrical contacts to the busbars can be present in the recesses, or the recesses can be insulated from the busbars in order to prevent electrical contact. Advantageously, each lamella has at least two recesses, through which runs a busbar that is in contact with all lamellae for current dissipation. The recesses are preferably located near the longitudinal ends of the slats.

In one embodiment of the slats, sliding contacts are thus arranged in the recesses of the slats, which are electrically conductively connected to the photovoltaic elements. The sliding contacts move along the busbar when the slats are pulled up and down. The electrical contact from the movable slats or sliding contacts to the stationary busbars is advantageously maintained even when the slats are tilted or rotated.

The busbars are advantageously contacted from at least two opposite sides. This enables better and more reliable contacting by pressing on two opposite sides.

One embodiment of the sliding contacts provides that the sliding contacts are designed as at least one electrically conductive contact pin. Advantageously, two contact pins are formed, which establish the electrical contact to a busbar in a recess from two opposite sides. The contact pins are also advantageously spring-loaded, for example in the form of spring contact pins.

Another embodiment of the sliding contacts provides that the sliding contacts are designed as at least one electrically conductive brush, for example as a copper brush. Advantageously, an electrically conductive brush is arranged all around in the recess. Alternatively, two individual brushes can also be arranged in the recess at least on two opposite sides.

In another embodiment of the lamellae, an electrically insulating insert is formed in the recesses, so that the respective lamella has no contact with a busbar or just has no contact with a specific busbar of a plurality of busbars.

Due to the different design of the recesses with or without a sliding contact or with or without insulation, it is possible, on the one hand, to design more than two busbars or busbars that are at the same potential. Furthermore, the slats can be connected to the busbars in different series circuits, for example two or three slats can be connected in series.

The busbars are preferably in the form of an electrically conductive rod, ribbon or cord. A busbar that is flat and wide is particularly suitable, since this facilitates contacting. The busbars are basically made of a material that is as conductive as possible. In a preferred embodiment, a metal or an alloy, for example (made of) copper or aluminum, is suitable for this. A busbar advantageously extends over the entire height of the shading device.

Furthermore, the current discharge system according to the invention is advantageously protected from the effects of the weather such as rain, solar radiation, etc., in order to ensure the longest possible service life with little wear.

One embodiment of the current dissipation system therefore provides that rubber seals and/or brush seals are inserted at least in sections into the longitudinal openings of the guide rails. These seals do not completely close the longitudinal opening, but allow the guide pins to slide up and down through the seals.

• - die einfache Umsetzbarkeit durch vorgefertigte Leisten, die entlang der Längsöffnungen aufgebracht werden können;
• - Bürstendichtungen sind witterungs- und wasserbeständig;
• - der Austausch von Lamellen wird dadurch nicht beeinflusst; und
• - Schutz in allen Positionen der Lamellen.

The advantages of brush seals, for example made of nylon or perlon, are:

• - The ease of implementation by prefabricated strips that can be applied along the longitudinal openings;
• - Brush seals are weather and water resistant;
• - this does not affect the replacement of slats; and
• - Protection in all positions of the slats.

However, individual bristles can come loose and thus soil the busbars. A brush seal also does not offer complete protection against the ingress of moisture and dust.

• - Schutz vor Spritzwasser und Schmutz;
• - leichte Installation;
• - der Austausch von Lamellen wird dadurch nicht beeinflusst;
• - Schutz in allen Positionen der Lamellen.

The advantage of rubber seals, for example made of silicone rubber, is:

• - Protection against splashing water and dirt;
• - easy installation;
• - this does not affect the replacement of slats;
• - Protection in all positions of the slats.

However, there are high demands on the material of the rubber seals, as they should be permanently elastic and not become brittle. The friction of the guide pins on the seal is significantly greater with a rubber seal than with a brush seal.

Another embodiment of the power dissipation system provides that a fabric insert is arranged between the guide bolts of adjacent slats, which is stretched when the slats are in the lowered state and at least partially covers the openings of the guide rails. The material used is advantageously as flexible as possible, weather-resistant and breathable as well as waterproof and UV-proof.

• - die Längsöffnungen werden staub- und wasserdicht abgedeckt;
• - Installation schon mit mittlerem Aufwand möglich; und
• - eingedrungene Feuchtigkeit kann wieder verdunsten.

The advantage of fabric inserts is:

• - the longitudinal openings are covered dust- and watertight;
• - Installation possible with moderate effort; and
• - Penetrated moisture can evaporate again.

However, a fabric insert only protects the longitudinal opening when the slats are lowered. Depending on the material, the individual fabric areas can fray on the sides. Replacing individual slats is made more difficult by the fabric inserts attached to the slats.

In an advantageous embodiment of the power dissipation system according to the invention of a shading device with a large number of slats with photovoltaic elements, it is proposed that at least two slats in each case be electrically connected to one another in series to form a set of slats, with the connection points between the two slats of a set of slats being parallel to one another via a busbar in each case are electrically coupled.

• - die potentialgleichen Verbindungsstellen zwischen der jeweils ersten Lamelle und der zweiten Lamelle eines Lamellensatzes über eine Sammelschiene auf einer ersten Seite der Beschattungseinrichtung elektrisch verbunden sind, und
• - jeder Lamellensatz an je eine positive und eine negative Sammelschiene auf der zur ersten Seite gegenüberliegenden zweiten Seite der Beschattungseinrichtung elektrisch angeschlossen ist. Hieraus ergibt sich dann, dass die Lamellen bezüglich ihrer Polarität von oben nach unten alternierend angeordnet sind.

If several sets of slats are used in the shading device, each consisting of two slats connected in series, this can be implemented by having exactly two slats connected in series for each set of slats, where:

• - the equipotential connection points between the respective first slat and the second slat of a set of slats are electrically connected via a busbar on a first side of the shading device, and
• - Each set of slats is electrically connected to a positive and a negative busbar on the second side of the shading device, opposite the first side. From this it follows that the lamellae are arranged alternately with regard to their polarity from top to bottom.

• - die potentialgleichen Verbindungsstellen zwischen den jeweils ersten Lamellen und den zweiten Lamellen über eine erste Sammelschiene auf einer ersten Seite der Beschattungseinrichtung elektrisch verbunden sind,
• - die potentialgleichen Verbindungsstellen zwischen den jeweils zweiten Lamellen und den dritten Lamellen über eine zweite Sammelschiene auf einer zweiten - der ersten Seite gegenüberliegenden - Seite der Beschattungseinrichtung elektrisch verbunden sind, und
• - jeder Lamellensatz an eine positive Sammelschiene und eine negative Sammelschiene auf jeweils einer Seite der Beschattungseinrichtung elektrisch angeschlossen ist.

If several sets of slats are used in the shading device, each consisting of three slats connected in series, this can be achieved by designing a current dissipation system in such a way that there are exactly three slats connected in series for each set of slats, where:

• - the equipotential connection points between the respective first slats and the second slats are electrically connected via a first busbar on a first side of the shading device,
• - the equipotential connection points between the respective second slats and the third slats are electrically connected via a second busbar on a second side of the shading device, opposite the first side, and
• - Each set of slats is electrically connected to a positive bus bar and a negative bus bar on either side of the shading device.

The invention also relates to a shading device, in particular an external venetian blind or a venetian blind, with a large number of slats with photovoltaic elements for generating electricity, with a current discharge system according to the invention as described above being present for dissipating the generated electricity.

The shading device is preferably a venetian blind or a blind, in particular a blind canopy. The invention is also described in terms of a shading device designed as an external venetian blind.

The structure of the external venetian blind corresponds to that of a conventional external venetian blind. Photovoltaic elements for power generation are attached to the slats, for example as a complete coating of the slats or individual areas on the slats. Both conventional photovoltaic elements of the first generation and also photovoltaic elements of the second or third generation can be used.

One embodiment of the shading device, in particular an external venetian blind, provides that the curtain comprises at least a first slat pack and a second slat pack, the slat packs being tilted differently about the respective longitudinal axes of the slats. This type of curtain is also generally referred to as a two-part curtain. Preferably, an upper set of disks can be rotated or tilted separately from the remaining disks. For example, a lower area of the curtain can be completely closed for power generation, while an upper area is still open or at least partially open to allow daylight to enter a room.

The invention is described in more detail below on the basis of the preferred exemplary embodiments with the aid of the figures, with only the features necessary for understanding the invention being shown.

• 1: eine schematische Perspektivansicht zweier Lamellen mit dem erfindungsgemäßen Stromabführungssystem,
• 2: einen vergrößerten Ausschnitt einer Lamelle gemäß der 1 im Bereich einer Aussparung,
• 3: eine schematische Draufsicht des Ausschnitts gemäß der 2,
• 4: eine schematische Querschnittsansicht des Ausschnitts gemäß der 2,
• 5: eine schematische Darstellung eines Raffstores mit Stromabführungssystem und einer ersten Reihenschaltung der Lamellen,
• 6: schematisch vereinfachte Darstellung der elektrischen Serienschaltung des Raffstores gemäß 5,
• 7: eine schematische Darstellung eines Raffstores mit Stromabführungssystem und einer weiteren Reihenschaltung der Lamellen, und
• 8: schematisch vereinfachte Darstellung der elektrischen Serienschaltung des Raffstores gemäß der 7.

They show in detail:

• 1 : a schematic perspective view of two slats with the current discharge system according to the invention,
• 2 : an enlarged section of a lamella according to the 1 in the area of a recess,
• 3 : a schematic top view of the section according to FIG 2 ,
• 4 : a schematic cross-sectional view of the section according to FIG 2 ,
• 5 : a schematic representation of an external venetian blind with power dissipation system and a first series connection of the slats,
• 6 : Schematically simplified representation of the electrical series connection of the external venetian blind according to 5 ,
• 7 : a schematic representation of an external venetian blind with power dissipation system and another series connection of the slats, and
• 8th : Schematically simplified representation of the electrical series circuit of the external venetian blind according to 7 .

In the 1 a schematic perspective view of two slats 7 with the current discharge system according to the invention is shown. The slats 7 are part of a shading device designed as a venetian blind. For a better overview, the guide bolts on the lateral longitudinal ends of the slats as well as the drawstrings for moving the slats 7 and the other components of the external venetian blind are not shown. A flat photovoltaic element 7a for generating electricity is formed on each of the slats 7 . The slats 7 are shown tilted about their longitudinal axis.

The current removal system according to the invention comprises two busbars designed as electrically conductive rods 4 . The rods 4 are at their upper and lower ends - connected to a power grid or a power storage unit - not shown here. Both rods 4 are at different potentials. When moving the slats 7, the rods 4 remain stationary, and in particular are not moved up and down. The slats 7 each have two laterally arranged recesses 2 through which the rods 4 are guided. The current generated in the photovoltaic elements 7a is discharged to the rods 4 via sliding contacts in the cutouts 2 . For this purpose, the photovoltaic elements 7a have an electrical connection 6, for example wiring, to the sliding contacts.

In the embodiment shown here as an example, see also 2 , the sliding contacts are designed as brushes 5. In the 3 a schematic top view of the lamella 7 in the area of the recess 2 is shown again. The brush 5 is formed circumferentially in the recess 2 so that the round bar 4 is contacted by the brush 5 on all sides. As a result, changes in the length of the lamellae 7 caused by temperature can also be compensated for without the electrical contact breaking.

In the 4 is a schematic cross-sectional view through the lamella 7 in the area Recess 2 shown. It is easy to see that the rods 4 are evenly contacted by the brush 5 on both sides.

The 5 shows an embodiment according to the invention of the upper part of an external venetian blind with a slat box 8 and a curtain whose slats 7.1 and 7.2 are provided with photovoltaic elements which are connected to one another in sets in series and each form a set of slats 7. In this case, photovoltaic elements of the slats are connected in sets to the busbars 4+ and 4- for current discharge, with one connection of the photovoltaic elements to the busbar 4.z being established for each set in such a way that a total of each set of slats 7 has a serial connection between the photovoltaic elements of the two slats 7.1 and 7.2 arises and thus the voltage U1 and U2 generated with the photovoltaic elements is added to a total voltage Uges and is doubled in the ideal case. How from the 9 As can be seen, the busbar for the intermediate potential 4z runs on one side on the left in one guide rail 1, while the two current discharge rails 4+ and 4- run in the right-hand guide rail 1.

For a clearer presentation, the schematic electrical circuit of the photovoltaic elements mounted on the slats 7.1 and 7.1 is shown in FIG 5 again in the 6 shown. In this case, the negative or grounded busbar 4- is arranged on the left, from which derivatives lead to the respective first lamella 7.1 of a lamella set 7. The first and second laminations 7.1 and 7.2 are connected together and with reversed polarity to the busbar 4.z, a common intermediate potential of the voltage U1 being present there between the respective first and second laminations 7.1 and 7.2. The respective second slats 7.2 are then connected to the positive side of their photovoltaic elements with their voltage U2 to the busbar 4+, with a total voltage Uges=U1+U2 being generated between the busbars 4- and 4+. The two busbars 4+ and 4- serve to carry away current with the potential of the total voltage Uges and combine the total power output of the external venetian blind according to the invention.

The external venetian blind according to the invention thus consists of a large number of slat sets 7 connected in parallel from slats 7.1 and 7.2 connected in series, the intermediate potential between all the first slats 7.1 and all second slats 7.2 being connected to one another.

Another embodiment of the external venetian blind according to the invention provides that three slats 7.1, 7.2 and 7.3 of a set of slats 7 are connected in series and the sets of slats 7 of the entire external venetian blind are connected in parallel and the first, second and third slats 7.1, 7.2 and 7.3 are connected to one another in parallel . Such an embodiment is exemplified in 7 shown. This shows the upper part of an external venetian blind with a slat box 8 with laterally arranged guide rails 1 designed according to the invention and three sets of slats 7. Each set of slats 7 contains a first, second and third slat 7.1, 7.2 and 7.3, each with a photovoltaic element arranged thereon. A busbar 4+ and 4- is arranged on the right and left in the guide rails, which on the one hand is connected to an external power connection and on the other hand electrically connects the sets of laminations 7 . In addition, a busbar 4.z is arranged in each of the lateral guide rails 1, which connects the individual slats 7.1 with 7.2 and 7.2 with 7.3 in series and at the same time all first slats 7.1, all second slats 7.2 and all third slats 7.3 in parallel.

A schematic representation of this electrical circuit from the 7 is in the 8th shown. There are four sets of slats 7, each consisting of the three slats 7.1 to 7.3. These three slats 7.1, 7.2 and 7.3 are connected to one another in series for each set of slats 7. At the same time, the sets of laminations are each connected in parallel via busbars 4- and 4+. In addition, there is also a parallel connection to the same intermediate potentials of the individual slats 7.1 and 7.2 via the two busbars 4.z, with these busbars 4.z each being designed to be insulated from the outside. In this way, the operating voltage Uges achieved can be increased to the sum of the individual voltages U1+U2+U3 of the first, second and third segments 7.1, 7.2 and 7.3 in order to keep transmission losses as low as possible. At the same time, the power output of the slat sets 7 is added up according to their number in the external venetian blind.

Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. In particular, the invention is not limited to the specified combinations of features, but other combinations and sub-combinations that are obviously executable for the person skilled in the art can also be formed from the disclosed features. Therefore, the invention also includes and discloses embodiments that are not explicitly shown or explained in the figures, but by separate combinations of features from the explained forms guides emerge and can be generated. Likewise, it is also within the scope of the invention to cause a mechanical reversal of the functions of the individual mechanical elements of the invention.

Reference List

1

guide rail

2

recess

4

busbar / rod

4+

positive busbar

4-

negative busbar

4.z

Busbar for intermediate potential

5

brush

6

Connection between sliding contact and photovoltaic element

7

Louvers with photovoltaic elements

7a

photovoltaic element

7.1

first slat with photovoltaic element of a serial set of slats

7.2

second slat with photovoltaic element of a serial set of slats

7.3

third slat with photovoltaic element of a serial set of slats

8th

slat box

9+

positive busbar

9-

negative busbar

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102007031236 A1 [0002]
• DE 102014200359 A1 [0002]
• DE 212019000358 U1 [0003]

Claims (14)

Power dissipation system for a shading device, in particular an external venetian blind or a blind, at least with a large number of slats (7) with photovoltaic elements (7a) for generating electricity, there being at least one busbar (4) which runs through the slats (7) and supplies them electrically conductively connected to one another in order to dissipate the electricity generated in the photovoltaic elements (7a). Current removal system according to the above Claim 1 , characterized in that at least two busbars (4) running through the lamellae (7) are formed. Current removal system according to the above patent claim 2 , characterized in that exactly two busbars (4), which are electrically connected to the photovoltaic elements (7a), run through each lamella (7). Current removal system according to any of the preceding patent claims 1 until 3 , characterized in that the lamellae (7) have recesses (2) through which the busbars (4) are guided. Current removal system according to the above patent claim 4 , characterized in that in the recesses (2) of the lamellae (7) sliding contacts are arranged, which are electrically conductively connected to the photovoltaic elements (7a). Current removal system according to the above Claim 5 , characterized in that the sliding contacts are designed as at least one electrically conductive contact pin. Current removal system according to any of the preceding patent claims 5 until 6 , characterized in that the sliding contacts are designed as at least one electrically conductive brush (5). Current removal system according to any of the preceding patent claims 4 until 7 , characterized in that an electrically insulating insert is formed in the recesses (2). Current removal system according to any of the preceding patent claims 1 until 8th , characterized in that the busbars (4) are designed as an electrically conductive rod, flat strip or cord. Current removal system according to any of the preceding patent claims 1 until 9 , characterized in that at least two lamellae (7.1, 7.2, 7.3) are electrically connected to one another in series to form a set of lamellae (7), the connection points (9) between the lamellae (7.1 with 7.2 and 7.2 with 7.3) being parallel to one another are each electrically coupled via a busbar (4.z). Current removal system according to the above Claim 10 , characterized in that each set of lamellae (7) has exactly two lamellae (7.1, 7.2) connected in series, with: - the equipotential connection points (9) between the respective first lamella (7.1) and the second lamella (7.2) via a busbar ( 4.z) are electrically connected on a first side of the shading device, and - each set of slats (7) is electrically connected to the positive and negative busbars (4+, 4-) on the second side of the shading device opposite the first side, the Polarity (+, -) of the slats in the shading device is designed to alternate from top to bottom. Current removal system according to the above Claim 10 , characterized in that each set of lamellae (7) has exactly three lamellae (7.1, 7.2, 7.3) connected in series, with: - the equipotential connection points (9) between the respective first lamella (7.1) and the second lamella (7.2) being first busbar (4.z) are electrically connected on a first side of the shading device, - the equipotential connection points (9) between the respective second slat (7.2) and the third slat (7.3) via a second busbar (4.z) on a second side of the shading device - opposite the first side - each set of slats (7) is electrically connected to a positive busbar (4+) and a negative busbar (4-) on each side of the shading device. Shading device, in particular an external venetian blind or a venetian blind, at least having a curtain with a large number of slats (7) with photovoltaic elements (7a) for generating electricity, characterized in that a current discharge system according to one of the preceding ones is used to discharge the electricity generated patent claims 1 until 12 present. Shading device according to the above Claim 13 identified thereby characterized in that the curtain comprises at least a first set of slats and a second set of slats, wherein the slat sets can be tilted differently about the respective longitudinal axes of the slats.

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