DE102009019937A1 - Sequence solar cell arrangement for use in photovoltaic system, has sequence solar cells and reflectors, where solar cells have two photoactive layers and refractive intermediate layer - Google Patents

Abstract

The sequence solar cell arrangements (11,12) have sequence solar cells (2) and reflectors, where the solar cells have two photoactive layers (4) and a refractive intermediate layer. The photoactive layers are arranged parallel to each other. The intermediate layer is arranged between two photoactive layers. The solar cells and the reflector are arranged at a distance from each other by an intermediate space (6). An independent claim is also included for a photovoltaic system.

Description

The The present invention relates to the field of photovoltaics a most efficient arrangement of stacked solar cells with reflective intermediate layer, for example in a photovoltaic module.

in the The field of photovoltaics is played by tandem or stacked solar cells increased in recent years a role. Under tandem solar cell in the prior art, on the one hand, a stacked solar cell with two or a plurality of photoactive by interlayer separated Layers, on the other hand, a folded tandem solar cell with two V-shaped to each other photoactive layers Understood.

simple solar cells have the disadvantage that only a limited Absorption spectrum can be used from. In the case of organic Solar cells adds that the light absorption in addition is limited. By absorbing light with an energy above the band edge of the organic semiconductor components become freely movable Carrier generated. These have to get through move the photoactive layer and extract at the contacts become. Low charge mobility and in Regarding this result in low extinction coefficients to that either with very thin photoactive layers a part of the incident radiation is not absorbed (absorption limitation) or, for thicker photoactive layers, a part the photogenerated charge carrier within the residence time recombined in the photoactive layer (transport limitation).

In order to increase the absorption, it has been proposed in the prior art to arrange two individual solar cells in a V-shape relative to one another and to choose the angle between the two individual cells in such a way that the angle of incidence of light is adapted to the respective materials. Such split solar cells are used for example in the DE 41 41 083 A1 described.

The Disadvantages of the V-shaped arrangement of solar cells exist in that a maximum of two solar cells with possibly different Band gap can be used. Furthermore First, 50% of the incident radiation falls on the Solar cell with lower band gap. This is then disadvantageous if the absorption spectrum of the solar cell with the small band gap (with the absorption edge at longer wavelengths) with the absorption spectrum of the solar cell with the larger band gap overlaps (with the absorption edge at smaller wavelengths).

The trend have organic solar cells with optimized donor / acceptor system with an absorption edge at longer wavelengths a lower open terminal voltage than solar cells with a Absorption edge at smaller wavelengths. Due to the Fact that often same acceptor materials with great Band gap can be used to absorb donor acceptor Systems with different absorption edge at low wavelengths. As a result, in the worst case of lighting the solar cells with the absorption edge at high wavelengths First, some of the high energy radiation is not used electrically can be because the energy is released via thermalization becomes.

On the other hand, tandem solar cells can also be designed as stacked solar cells. By stacking single cells with different absorption edges and their serial or parallel interconnection, the solar energy conversion efficiency can be significantly increased compared to single solar cells. The reason is that a wider range of the solar spectrum can be used efficiently. The individual solar cells (or the photoactive layers) are separated by an intermediate layer. In the stack arrangement, this intermediate layer must have the lowest possible absorption of the incident radiation so that light can also be incident on the second photoactive layer. In the case of the serial interconnection of the solar cells, this layer must cause a jump in the vacuum level between the individual cells and thus efficient recombination of charge carriers of adjacent cells. In addition, the surface current densities of the individual layers must be balanced. In the case of the parallel interconnection of the individual cells, the surface conductivity of this intermediate layer must be sufficiently high for efficient charge carrier extraction. In order to achieve optimum light absorption, an exact adaptation of the layer thicknesses with their specific refractive indices is required. This requires an exact manufacturability of these layer thicknesses. The deposition of the functional layers (electrodes, semiconductors, doped semiconductors, recombination layers) involves vacuum processes and wet-chemical coating and printing processes. The compatibility of the successive deposition steps is essential, both in terms of functionality (compatibility of solvents) and on the economy (change between vacuum and wet chemical processes). Such stacked solar cells, in particular with organic photoactive layers are z. B. in the DE 103 26 546 A1 disclosed. A disadvantage of this arrangement, however, has proven that complex requirements are placed on the intermediate layers, such as low absorption, suitable refractive index, high surface conductivity. The realization of these requirements is tech demanding and leads to increased costs in the production.

task The present invention is now an arrangement of stacked solar cells to provide the disadvantages of the in the state of Technique known solar cells and solar cell assemblies eliminated. The inventive arrangement of stacked solar cells it should be increased efficiency due to increased Realize light absorption and an extended absorption spectrum. In addition, the arrangement is technically simple and inexpensive to be realized.

These The object is achieved by the stacked solar cell arrangement according to claim 1 and the photovoltaic system according to claim 12 solved. advantageous Further developments of the stacked solar cell arrangement according to the invention are mentioned in the dependent claims.

According to the invention a stacked solar cell arrangement at least one stacked solar cell, which at least two photoactive layers and at least one contains reflective intermediate layer, and at least having a reflector. The at least two photoactive layers are arranged substantially parallel to each other and are separated by the reflective intermediate layer. The Stack solar cell and the reflector in turn are separated by a gap spaced apart and aligned with each other so that Radiation reflected by the stacked solar cell at least partially falls on the reflector and / or that reflected by the reflector Radiation falls at least partially on the stacked solar cell. The structure of the invention thus allows a multiple reflection of the incident radiation. Thus, for example Radiation of a certain wavelength range, which absorbable by the photoactive layer but at the first Passing through the photoactive layer was not absorbed, but was blasted in the direction of the reflector, by reflection at the reflector be irradiated again on the photoactive layer.

Of the by the at least one solar cell and the at least one reflector spanned space preferably has one as an inlet opening defined area on the side facing the incident light and an area defined as an exit opening the side of the gap facing away from the incident light.

Around now to use the multiple reflection as effectively as possible, is a substantially parallel arrangement of the at least one Stack solar cell and the at least one reflector to each other advantageous. Hits light at a steep angle of incidence the reflector or the stacked solar cell, so is at a parallel Arrangement even with a small extent of reflector and stacked solar cell, d. H. at a small distance between the inlet and outlet openings of the space, a multiple reflection possible. In order to there is a possibility that the respective reflected Part of the radiation of a certain wavelength range, which is absorbable by the single solar cell, again on the photoactive layer strikes and at least partially absorbs becomes.

Preferably instead of the at least one reflector, a further stacked solar cell with at least two parallel to each other photoactive Layers, which by at least one reflective intermediate layer separated from each other used. At the through the gap spaced from each other, opposite each other photoactive layers of the stacked solar cell and the instead of the Reflectors used further stacked solar cell can be the incident Radiation be partially or completely absorbed, partially reflected become. Due to the multiple reflection within the gap can be the absorption of light with the photoactive layers absorbable wavelength range can be optimized.

Either the opposite photoactive layers the gap forming stack solar cells and the photoactive layers of a single stacked solar cell can be radiation the same or a different wavelength range absorb. In the same photoactive layers or in light absorbing in the same wavelength range photoactive Layers thus becomes the absorption of radiation of precisely this wavelength range improved. It is advantageous if in particular the one another opposite photoactive layers light different Absorb wavelength, since thus the probability is increased, that in the space incident light is absorbed. In this case it is possible to have an extended one Exploit absorption spectrum. Preferably, the photoactive Layers then adapted to the incident radiation. For example Light irradiated, which radiation in the wavelength range A and in the wavelength range B, the photoactive layers can be chosen such that one of the photoactive layers absorbed the wavelength range A, while the other photoactive layer is light of the wavelength range B absorbed.

alternative can serve as a reflector and a mirror. Preferably should the mirror can be designed to be reflective on both sides.

The mirror can be a dielectric mirror or metallic mirror, or even a layer system of metallic and dielectric layers. Suitable material for the dielectric layers is CrO, TiO _x (titanium oxides), ZnO, WO ₃ , V ₂ O ₅ , MoO ₃ , indium tin oxide (ITO), antimony-doped tin oxide (ATO). As materials for metallic layers, for example, aluminum, chromium, titanium or silver can be used. The layer thicknesses of the individual layers amount to a few nm to a few 100 nm. The requirements are a high reflectivity, especially in the wavelength range in which the opposite photoactive layer absorbs.

The at least two photoactive layers of the at least one stacked solar cell may have the same or different materials. The photoactive layers then absorb radiation of the same or a different wavelength range. When Materials include organic semiconductors, inorganic semiconductor nanoparticles and mixtures of both. Preferably, in the choice of Paid attention to materials for photoactive layers that the wavelength range or wavelengths in which the absorbing photoactive layers, from the entire solar spectrum are selected. The solar spectrum bridges a wavelength range from 200 to over 2000 nm. The intensity maximum, however, lies at wavelengths between 350 to 1000 nm, so that preferably photoactive layers, which in the subrange of 350 to 1000 nm.

The photoactive layers of a stacked solar cell can be parallel or in series.

At least one of the at least two photoactive layers of the stacked solar cell absorbs radiation of a selected wavelength subrange, which absorbs from the at least one photoactive layer is, in whole or in part.

The at least one reflective intermediate layer of the stacked solar cell is preferably a reflective electrode or a reflective recombination layer. Suitable reflective electrodes are layer systems which are constructed either from dielectric layers or from a combination of metallic and dielectric layers. Suitable material for the dielectric layers is CrO, TiO _x (titanium oxides), ZnO, WO ₃ , V ₂ O ₅ , MoO ₃ , indium tin oxide (ITO), antimony-doped tin oxide (ATO). As materials for metallic layers, for example, aluminum, chromium, titanium or silver can be used. The layer thicknesses of the individual layers amount to a few nm to a few 100 nm. The entire reflective electrode, which is arranged between at least two photoactive layers, preferably has a total thickness of between 5 nm and 1 mm.

Between the photoactive layers adjacent to the reflective layer is preferably a good contact to the hole transport level or to the electron transport level, depending on whether it is an anode or a cathode. A good contact forms u. a. out, when the work function of the electrode with the Fermieenergie for the respective charge carriers coincide and the semiconductor in direct contact with the electrode surface is.

When Electrode contacts vapor-deposited on a photoactive layer can be Al, Ag, Ca or LiF. When Electrode contacts on which a photoactive layer deposited is to be used, preferably Ti or Cr can be used.

On the side facing away from the reflective layer of the photoactive Layers is preferably arranged a transparent electrode. When transparent electrodes come z. Indium tin oxide (ITO) aluminum doped tin oxide, layer systems of thin silver layers and metal oxides and organic doped semiconductor layers in Question.

Builds according to the invention the at least one solar cell and the at least one corresponding arranged to stack solar cell reflector a gap. This can be done with air or with a dielectric material matched refractive index and low absorption of light in the absorption region be filled the photoactive layers. The gap between the at least one stacked solar cell and the at least a reflector is formed such that the distance between the Solar cell and the reflector some 100 nm to several 10 cm, preferably some 100 nm to a few centimeters, or in this range varied. Depending on the application, the distance can be adjusted accordingly become. The distance affects the frequency of reflection events the passage of light through the gap.

In the region of the inlet opening or outside the intermediate space in the direction from which light is radiated, optical elements and / or scattering layers can be arranged. Additionally or alternatively, optical elements (structures) or lenses may also be arranged in the region of the outlet opening or outside the intermediate space on the side of the outlet opening of the intermediate space. As optical elements, for example, mirror or lenses offer, which are preferably planar, planar tilted, convex or concave. By attaching optical elements and / or scattering layers, the light is caused to be at a suitable angle on the reflector or stacked solar cell le hits. In particular, in the case that the stacked solar cell and the reflector are arranged substantially parallel to each other, and that the light enters the gap in parallel thereto, optical elements and / or scattering layers are advantageous.

Preferably is the stacked solar cell array so relative to the direction of incidence the radiation is inclined to the incident radiation at an angle α on the side of the stacked solar cell facing the incident radiation or of the reflector. The angle α is preferably a value between 0 ° and 90 °, more preferably between 30 ° and 75 °. It is advantageous, the angle of incidence on the properties of the photoactive layers adapt.

each Stacking solar cell can be reflective on one or both sides Layer two or more photoactive layers, which in turn by Interlayers, such as contact layers or transparent Electrodes are separated from each other. The one on one Side of the reflective layer arranged photoactive layers can be made of the same or different materials be composed and can light in the same or absorb different wavelength ranges.

A stacked solar cell assembly according to the invention can also contain more than one stacked solar cell and a reflector. The stacked solar cells are then preferably arranged next to each other, so that two end faces, which are not in the area of entry or Outlets are adjacent. alternative Two solar cells can also be arranged one above the other be. The two adjoining solar cells can be aligned parallel to each other or a specific Include angle. The reflectors are then preferred arrange accordingly.

The at least one stacked solar cell and / or the at least one reflector the stacked solar cell array according to the invention are preferably applied to a substrate. At the substrate it is preferably a transparent substrate, so that Light propagates in the medium that forms the substrate can. As a substrate, therefore, preferred are dielectric materials with adjusted refractive index and low absorption of light in the absorption area the photoactive layers used.

For example can be a substrate on its top or on both sides have a sawtooth profile, but only one each Side of each saw tooth with a stacked solar cell is busy. The unoccupied side is preferably translucent.

The at least one stacked solar cell and / or the at least one reflector the solar cell array according to the invention can be placed on a tracker. So changes the direction of irradiation of the incident light, so can the stacked solar cell and / or the reflector are readjusted accordingly, that the incident light undergoes multiple reflection.

A Variety of stacked solar cell assemblies according to the invention form a photovoltaic system. In an inventive Photovoltaic system are the individual stacked solar cell assemblies next to each other (ie opposite ends of the Arrangements, which are not in the area of the inlet and outlet openings lie, are adjacent), offset next to each other (ie Sides of the individual arrangements are opposite each other), one behind the other, one above the other and / or offset one above the other arranged. Adjacent solar cells or reflectors, which one above the other and / or juxtaposed, can be spaced or be spaced from each other. Indicates the photovoltaic system for example, a plurality of solar cell arrangements according to the invention with vertically oriented solar cells and reflectors on, wherein the inlet opening of the intermediate space through the upper horizontally oriented end faces of the solar cells or reflectors is formed, so can several stacked solar cell assemblies such be aligned side by side, that all solar cells and all the reflectors are substantially parallel to one another are arranged and that in each case a vertical end face a solar cell or a reflector with a vertical end face an additional solar cell or an additional Opposite reflector. Furthermore you can also in each case the horizontal end faces opposite each other.

In a photovoltaic system, the individual stacked solar cell assemblies Stacked solar cells with photoactive layers, which light the same or absorb a different wavelength range, exhibit. For example, several Sta pelsolarzellenanordnungen one above the other arranged, it is appropriate that the stacked solar cell assemblies with photoactive layers with large band gap are arranged at the top while photoactive below Layers with a smaller band gap are attached. It is advantageous if initially short-wave light is absorbed and long-wavelength light is absorbed lower down.

The individual photoactive layers or the photoactive layers of the stacked solar cell arrangements in a photovoltaic system can be parallel lel or serially connected.

in the Below are some examples of inventive Stack solar cell assemblies and photovoltaic systems given. It demonstrate

1 a cross section through two successively arranged solar cell assemblies,

2A to 2G each a section of a photovoltaic system according to the invention,

3A to 3D Interconnection options for stacked solar cells with reflective intermediate layer, and

4A to 4C Cutouts from a photovoltaic system according to the invention.

1 shows the cross section through a first stacked solar cell assembly 11 and a second stacked cell array 12 , The first and second stacked solar cell assemblies 11 and 12 each have two stacked solar cells 2 , which are aligned parallel to each other, on. The stacked solar cells 2 each have a reflective electrode 3 on each of its two flat sides a photoactive layer 4 is arranged. The two photoactive layers 4 point to their reflective electrode 3 side facing away from a transparent electrode 5 on. Between the two stacked solar cells 2 a stacked solar cell array 11 or 12 is a gap 6 educated. Each of the two solar cell arrangements 11 and 12 has an entrance opening 7 and an exit port 8th on, through which the light 9 (shown here as arrows schematically) can enter or exit.

The two solar cell arrangements 11 and 12 are arranged to each other so that the individual stacked solar cells 2 are essentially parallel to each other and that from the outlet opening 8th the first solar cell array 11 escaping light through the inlet 7 the second solar cell array 12 can enter into this. The multiple reflection of the incident light within the first and second solar cell array 11 and 12 is by arrows 9 indicated.

In 2A is a vertical section through a section of a photovoltaic system shown. It is shown a strip-shaped arrangement. The individual stacked solar cells 2 and optionally reflectors 21 or solar cell arrangements 11 . 12 . 13 stand vertically and are aligned parallel to each other. The incident light passes at an angle β of about 45 ° on the left side of a stacked solar cell 2 or a reflector 21 and is partially absorbed and partially reflected. The arrows 9 show the multiple reflection within a space 6 a stacked solar cell array 11 . 12 . 13 , In this case, the ratio of fin spacing (distance between at least two parallel solar cells 2 or reflectors 21 ) and the lamella length (in this case the extent of the solar cells in the vertical direction with vertical alignment of the solar cells) the frequency of the reflection events when passing through the light 9 through the gap 6 ,

2 B shows three different stacked solar cell arrays 11a . 11b and 11c , which are each vertically aligned. In the case of the stacked solar cell array 11a the light falls into the space at an angle γ of approx. 45 ° to the vertical 6 and hits at an angle β of about 45 ° on the stack solar cell 2 or the reflector 21 on.

In the case of the solar cell arrangement 11b the light falls from one direction parallel to the vertical into the space 6 one. In the area of the entrance opening 7 the solar cell arrangement 11b there is a lens 70 which the incident light 9 deflects, making it again at an angle β of about 45 ° on the stacked solar cells 2 or the reflector 21 incident. Below the outlet 8th the stack solar cell 2 there is a planar mirror 71 , which the already multiple reflected light 9 back into the gap 6 throws.

In the case of the stacked solar cell array 11c enters the light 9 parallel to the vertical in the gap 6 and traverses this, without cells on the pile solar cells 2 or reflectors 21 to be mirrored. In the area below the outlet opening 8th there is a concave mirror 72 , This reflects the light 9 such that it is at an angle β of about 45 ° to the solar cells 2 or reflectors 21 impinges and undergoes multiple reflection.

2C again shows the vertical section through a section of a photovoltaic system according to the invention. The individual stacked solar cells 2 or reflectors 21 are aligned at an angle δ of about 45 ° to the horizontal and arranged parallel to each other. The light 9 falls from a vertical direction into the gap 6 each solar cell array 11 . 12 . 13 and hits the up-facing page 2a the solar cells 2 , The incident light 9 is partially absorbed, partially reflected.

2D essentially shows a section, as he already has for 2C was declared. However, there are two stacked solar cells each 2 or reflectors 21 arranged one above the other without gaps, so that an extended space is formed and the incident light is reflected more frequently.

A similar picture also shows 2E , wherein the individual solar cells arranged one above the other 2 spaced from each other are attached.

2F again shows a section through a section of a photovoltaic system, in turn, each two stacked solar cells 2 or reflectors 21 are arranged one above the other. The top of the stack solar cells 2a or reflectors 21a are like in 2 B represented, arranged. The lower stacked solar cells 2 B or reflectors 21b on the other hand are arranged mirror-inverted, so that in each case an upper and a lower stacked solar cell or reflector enclose an angle of approximately 90 °.

2G shows a view of a photovoltaic system. This is designed such that in each case two solar cell arrangements according to the invention 11a . 12a . 11b . 12b a diamond-shaped incidence opening 7 formed. The smaller angle of the diamond shape is denoted by α. The top view now shows a section of a rhomboid net. The light is incident in this arrangement in a variety of "tunnels" and is reflected or absorbed at the "tunnel walls".

3A shows a stacked solar cell 2 as used in the stacked solar cell arrangement according to the invention 11 is usable. The stacked solar cell 2 has a reflective electrode 3 with an upper and a lower side 3a and 3b on. On the lower and the upper side 3a and 3b the reflective electrode 3 is in each case a photoactive layer 4 arranged. The of the reflective electrode 3 opposite side of the photoactive layer 4 each has a transparent electrode 5 on. With 9 is again the incident light designates.

3B now shows a stacked solar cell 2 as in 3A in parallel. The reflective electrode is used 3 for example, as an anode and the transparent electrodes 5 as a cathode or vice versa. The two transparent electrodes 5 are connected.

In 3C is now a stacked solar cell in series circuit shown. A reflective recombination layer 3 has on its one side an n-doped one 41 and on its lower side a p-doped one 42 Shift up. On each of the reflective recombination layer 3 opposite side of the doped layers 41 . 42 there is a photoactive layer 4 , in turn, with a transparent electrode 51 . 52 is in contact. The transparent electrode 51 on the side of the reflective recombination layer 3 on which the n-doped layer 41 is arranged, serves as the anode, the transparent electrode 52 on the other side of the reflective recombination layer 3 with the p-doped layer 42 serves as a cathode.

In 3D are now stacked solar cells 2 shown with through-hole. Four through-hole stacked solar cells can be seen 2 , In the middle is an electrically conductive layer 31 , which are all stacked solar cells 2 connects with each other. Each stacked solar cell 2 points above and below the electrically conductive layer 31 each a dielectric layer 43 on. The of the electrically conductive layer 31 opposite side of the dielectric layer 43 is with a reflective electrode 3 provided, which can each serve as an anode. On the dielectric layer 43 opposite side of the reflective electrodes 3 each is a photoactive layer 4 , All four stacked solar cells 2 are in a transparent electrode 5 embedded with transverse conductivity, which is used as the anode. The reflective electrodes 3 the individual stacked solar cells 2 are not with the transparent electrode 5 in contact. The reflective electrodes 3 as well as the transparent electrode 5 can also be used as a cathode.

The with the 1 and 2A to 2G described sections of photovoltaic systems or stacked solar cell arrays can be applied to flat substrates or on three-dimensionally structured substrates. The angle of inclination of the slats can be set according to the optimum conditions of use.

In 4A is a system on a structured substrate, as in 4B is shown represented. The surface topography corresponds to a sawtooth profile with a flank angle of 45 °.

4A shows the cross section through a sawtooth-shaped substrate 80 where each saw tooth is a vertical side 81 and a sloping side 82 having. On the inclined side 82 are stacked solar cells 2 with parallel connection. In the area of the peaks 83 of the sawtooth profile is a strip electrode 32 for contacting the transparent electrodes 5 arranged. In 4A are two such sawtooth profiles 80 arranged one above the other.

Such structures can be produced by micromechanical processing methods and also by interference lithography. After the formation of a primary structure, this can be transformed into an optically transparent material of the substrate 80 be replicated. The stacked solar cells 2 in this arrangement are connected in parallel. In this case, the intransparent electrode 3 a common electrode. The solar cell 2 can be built up with layers deposited from the solution as well as from deposited materials. Here the structure is based on the basis considered evaporated layers. The first layer is an optically transparent electrode 5 deposited with sufficiently high surface conductivity. The requirements for the surface conductivity depend on the width of the lamellae or the individual solar cell 2 and may be several hundred ohms for fins of tens of microns. To efficiently transport the stream in the direction of expansion of the slats 2 To ensure, can support a strip electrode 32 on the tips 83 of the sawtooth professional 80 be applied. This can be done either by vapor deposition of a metal layer at a shallow angle, or by printing. The strip electrode 32 should both transparent electrodes 5 to contact. Vapor deposition of the functional layers (transparent electrodes 5 , doped contact layers 41 . 42 , photoactive layers 5 ) of the solar cell 2 takes place almost vertically. It must be ensured only by the own shading that the vertical surfaces 81 of the substrate in the coating processes. The intransparent electrode 3 can consist of a shift system. The requirements are each a good (low barrier) contact to the respective semiconductor, as well as a sufficient surface conductivity. As electron contacts on the photoactive layer 4 Al, Ag, Ca, LiF have proven to be suitable for vapor deposition. As electron contacts on which the following photoactive layer 4 deposited Ti and Cr have been found to be suitable. As transparent electrodes 5 come z. As indium tin oxide (ITO), aluminum-doped tin oxide, layer systems of thin silver layers and metal oxides, as well as organic doped semiconductor layers in question. In the illustrated arrangement, two are structured with stacked solar cells 2 equipped substrates 80 arranged one above the other. This configuration allows the optical series connection of up to four solar cells 2 with different bandgap. To minimize reflection losses, both structures are 80 filled with a material with a similar refractive index and both planes optically coupled to each other.

An embodiment of flat, lamellar arranged solar cells 2 shows 4C , The slats 20 (here modules) are based on plated-through bifacial stacked solar cells 2 , The positioning can be done in an outer frame. The slats contribute to modules 20 series-connected solar cells 2 , The interconnection of the individual solar cell surfaces 2 to solar modules 20 with correspondingly high voltage should be in the direction of the longitudinal extent of the slats 20 to limit current by interconnecting complete solar cells 2 to get around.

The Stack solar cell assembly of the present invention allows in contrast to conventional unfolded tandem concepts a meaningful Irradiation order of more than two solar cells different Band gap and increases the solar energy convention efficiency by multiple reflection and serial arrangement of solar cells with increase different band gap.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 4141083 A1 [0004]
• - DE 10326546 A1 [0007]

Claims (15)

Stacked solar cell array with at least one Stacked solar cell and at least one reflector, the at least one stacked solar cell at least two parallel to each other arranged photoactive layers and at least one reflective Intermediate layer contains, wherein the at least one reflective Intermediate layer between two of the at least two photoactive layers is arranged, and wherein the at least one stacked solar cell and the at least one reflector through a gap from each other spaced apart and are aligned to each other, that reflected by the stacked solar cell radiation at least partially falls on the reflector and / or that reflected by the reflector Radiation falls at least partially on the stacked solar cell. Stacked solar cell array after the previous one Claim, characterized in that the at least one stacked solar cell and the at least one reflector substantially parallel to each other are arranged. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that the at least a reflector, a stacked solar cell or a mirror, preferably a double-sided reflecting mirror is. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that the at least two photoactive layers of the at least one stacked solar cell Radiation of the same or a different wavelength subrange absorb, wherein the one or more wavelength subregions are selected from the entire solar spectrum. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that at least one the at least two photoactive layers of the at least one Stacked solar cell radiation of a wavelength division, which is absorbable by the at least one photoactive layer, completely or partially absorbed. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that the at least a reflective intermediate layer of the stacked solar cell a reflective electrode or a reflective recombination layer. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that in the area or above an opening of the space through which Radiation enters the stacked solar cell array, and / or im Area of an opening of the space through which radiation exits the solar cell array, optical elements and / or scattering layers are arranged. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that the at least a stacked solar cell and / or the at least one reflector relative is inclined to the direction of incidence of the radiation such that the incident radiation at an angle α to the impinging incident side of the stacked solar cell impinges where 0 °> α> 90 °, in particular 30 °> α> 75 °, applies. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that two to each other adjacent stack solar cells, which at a certain angle aligned with each other, and two mutually adjacent reflectors, which are aligned at a certain angle to each other, facing each other, the two stacked solar cells and the two reflectors one above the other or side by side are arranged. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that the at least a stacked solar cell and / or the at least one reflector a substrate, preferably a transparent substrate applied are. Stacked solar cell arrangement according to one of the preceding Claims, characterized in that the at least a stacked solar cell and / or the at least one reflector a tracker are arranged. Photovoltaic system with a variety of stacked solar cell assemblies according to one of the preceding claims, characterized in that the stacked solar cell assemblies side by side, offset side by side, one behind the other, one above the other and / or offset one above the other are arranged. Photovoltaic system according to the preceding claim, characterized in that one above the other and / or side by side arranged stacked solar cell assemblies without spacing or from each other spaced apart. Photovoltaic system according to one of the preceding claims 12 or 13, characterized in that the stacked solar cell assemblies have photoactive layers, which radiation absorb the same or a different wavelength portion. Photovoltaic system according to one of the preceding Claims 12 to 14, characterized in that the photoactive Layers of stacked solar cells arranged one above the other Stacked solar cell assemblies with increasing distance from an opening, by which radiation in the or the interstices of the Photovoltaic system occurs, absorbing long-wave radiation.