EP1269542A1

EP1269542A1 - Method for producing a solar module with thin-film solar cells which are series-connected in an integrated manner and solar modules produced according to the method, especially using concentrator modules

Info

Publication number: EP1269542A1
Application number: EP01935948A
Authority: EP
Inventors: Wolfgang Harneit; Arnulf JÄGER-WALDAU; Martha Christina Lux-Steiner
Original assignee: Hahn Meitner Institut Berlin GmbH
Current assignee: Helmholtz Zentrum Berlin fuer Materialien und Energie GmbH
Priority date: 2000-03-30
Filing date: 2001-03-29
Publication date: 2003-01-02
Also published as: DE10017610C2; WO2001075976A1; JP4056744B2; DE10017610A1; US7019207B2; HK1053904A1; JP2003529938A; US20030121542A1

Abstract

Known methods for producing large-surface, integrated thin-film solar modules with an amorphous, poly- or microcrystalline absorber layer always comprise division and conversion structuring processes which can cause instabilities in the structuring and which are relatively expensive. According to the inventive methods, which can be used to produce substrate solar cells (116) and superstrate solar cells, the mask (100) that is used provides for structuring itself during the deposition of layers for the back electrode (106) and the absorber layer (110) through its geometrical form. The use of a mask (110) that can be reused as an independent element after use in this method allows for a relatively free range of possible geometrical forms. This also enables applications inside and outside buildings from an aesthetic and informal point of view, including in the area of a window. These types of applications are also supported by the possibility of a structural connection between the solar modules produced according to the inventive method and light-collecting concentrator modules, in order to considerably increase their average and total energy conversion efficiency.

Description

description

Method for producing a solar module with integrated series-connected thin-film solar cells and solar modules produced with the method, in particular using concentrator modules.

description

The invention relates to methods for producing a solar module with structured and integrated series-connected thin-film solar cells and to solar modules produced with the method. The solar cells can have both a substrate and a superstrate as the carrier layer.

Thin-film solar cells of both types have light-absorbing absorber layers made of inexpensive amorphous, polycrystalline or microcrystalline semiconductor materials, which can be deposited or built up on large-area substrates or superstrates by a variety of different methods. The low layer thickness of the absorber layers and the possibility of structuring during manufacture lower the manufacturing costs further, so that thin-film solar cells represent a cost-effective alternative to the currently cost-intensive silicon solar cells, which as single-crystal or multi-layer systems only become available after production sawn into individual cells and then how high-quality semiconductor products have to be processed. Through the photovoltaic conversion of solar energy into electrical power, thin-film solar cells generate voltage levels below 1 volt. In order to obtain a technically usable output at a voltage of typically 12 volts or 24 volts, a correspondingly sufficient number of individual solar cells are connected in series. With thin-film This Senen circuit can be integrated into the layer production process for solar cells. The entire surface of the coatings is divided into narrow strips using suitable structuring methods, for example paste writing methods and lift-off techniques, and mechanical and in particular laser processing methods. The aim of the structuring is to establish an electrical connection between to create the electrodes on the front and back of adjacent strip-shaped solar cells

US Pat. No. 4,675,467 discloses a method for connecting an integrated thin-film solar module in which both electrodes are already inserted in a pre-fabricated strip shape into an unstructured absorber layer. The conductive connections between the corresponding electrodes of adjacent solar cells are then removed by a structuring step using laser radiation The transparent substrate side produced in a covering area of the electrode strips. With a precisely defined energy dose, corresponding areas of the absorber layer are converted into low-resistance areas, but there is a risk of damage to the semiconductor material. Due to the lack of spatial structuring of the absorber layer, the semiconductor material of adjacent solar cells is not electrically opposed to one another insulated so that short-circuit currents reduce the power yield. Laser treatment requires highly precise dosing, positi Onioning and focusing of the laser beam used in order to be able to achieve the desired conversion effect in a precise location. Layer separation and damage in the immediate vicinity of the structure layer cannot be ruled out. Furthermore, the use of a transparent substrate with precisely defined, homogeneous layer thickness is always necessary in order to prevent the laser beam from penetrating from the substrate side here and to be able to precisely determine its dose-dependent penetration depth into the layers to be separated or converted No. 4,999,308 describes a similar method with prefabricated electrode strips, in which the laser treatment for region conversion is also carried out at the same time for separating the absorber layer in order to produce insulation trenches here by blasting off semiconductor material lost therewith. With this joint treatment, energy metering is a problem, in particular through which the conversion regions are created with a certain degree of uncertainty, even if the treatment is carried out from the top of the solar cells and not through the substrate. The use of two “scribing processes” for the successive separation of absorber layer and front electrode at different, laterally displaced locations is known from US Pat. No. 5,296,674. The separation is carried out by means of indirect laser radiation through the substrate as a protective layer, so that the absorber layer adjoins solar cells continues to be directly connected to one another. With this method, multiple positioning of a transparent substrate is necessary, with the acceptance of short-circuit currents.

From WO-9503628 a method for the antenna connection of an integrated thin-film solar cell module is known, in which all functional layers are structured separately in special process steps. In this method, a metal layer previously deposited over the entire surface of a transparent substrate is first divided into closely adjacent strips by an arbitrary structuring method to form a strip-shaped back electrode. After the subsequent full-surface coating with a thin semiconductor layer to form an absorber layer and a front layer to form a front electrode, two further, separate structuring steps are carried out by means of laser irradiation from the substrate side. The first laser radiation is used for the stripe-shaped structuring of the absorber layer and front electrode, with the second laser radiation in turn that portion of the absorber layer is converted into a low-ohmic area that lies in the overlap area between the opposite electrode strips of adjacent solar cells, so that an integrated conductive series connection is formed between the solar cells. The known method therefore requires structuring with a triple separation treatment, including two more complex laser beam treatments. The first serves the separation process of front electrode and absorber layer together. In particular, when laser-assisted removal of the sensitive semiconductor layer, there is always the risk of damaging or changing it. The second treatment for area conversion again requires precise laser energy metering with the problems already described above.

The described methods are based on the joint optimization task in the sense of maximized power output or a minimized area size of the solar modules produced from strip-like structured thin-film solar cells of both carrier layer types. Compared to single-crystal solar cells, such solar cells already have a lower energy efficiency, which, in comparison with the normal case (light concentration AM 1, 5), also rapidly reduces the light conditions. This means that with the usual fluctuations in light intensity between the seasons and from day to day depending on the weather and for indoor applications (down to 10% of the maximum available radiation), thin-film solar cells have significant power losses. This is one of the reasons why thin-film solar cells have so far hardly been used in areas with very different solar radiation and generally in indoor areas. In the case of single-crystal solar cells, it is known from a large number of publications to provide light-collecting concentrator modules made of optical elements which keep the light intensity in the effective range for the single-crystal solar cells or bring them into it. However, the aim of such known measures is not to maximize performance, but rather to reduce the very expensive, required solar module area as significantly as possible. For example, US Pat. No. 5,118,361 discloses a solar module made of single-layer tandem solar cells made of GaAs / GaSb, which is built into a housing, the cover of which is formed by a concentrator module made of individual plastic Fresnel lenses, which are arranged together with light-collecting funnels The individual solar cells are arranged in front of them. They are arranged in the module on a flexible interconnection tape with conductive and non-conductive strips. In a very similar arrangement for single-installation GaAs solar cells according to EP 0 657 948, their automated microchip-like interconnection is known, which is used for surface mimicking. Concentrator arrangements US Pat. No. 4,711,972 for single-crystalline silicon solar cells and US Pat. No. 5,505,789 for single-crystalline integrated solar cell chips made of GaAs are known from DEAs with line focus lenses in or as a module cover, which are particularly suitable for strip-shaped solar modules 197 44 840 A1 shows a solar module with an upstream concentrator module made of plastic Fresnel lenses, which as a structural unit for an improved energy balance can be tracked by tilting or shifting the position of the sun. EP 0 328 053 finally describes strip-shaped solar modules with a Fresnel lens in front , which are each integrated in a corner of a window pane of a double window and are intended to supply the power supply for a blind operation in the middle of the double window

However, none of these mentioned and other publications disclose the use of concentrator modules specifically for amorphous, polycrystalline or microcrystalline thin-film solar modules in any form of embodiment, so that such modules have so far been showing a relatively poor and extremely time-dependent and weather-dependent power balance, especially with regard to applications in In the case of known solar modules, even in the case of thin-film solar cells deposited over a large area on glass substrates, the window area is also given little or no consideration of optical design measures, which leads to relatively varied, purely technical aspects subject to solar module designs which are mainly used in the industrial area. Solar modules designed from an aesthetic point of view can be found, for example, in the form of roof tiles (cf. DE 42 279 29, DE 43 176 74) or in wristwatches in which different colors can also be taken into account (cf. EP 0 895 141).

Against the background of the preceding explanations and based on the prior art closest to the method according to the invention for a method for producing a solar module with structured and integrated series-connected thin-film solar cells, it is the object of the present invention to initially provide an improved manufacturing method with the least possible structuring effort , The aspects of the improvement, which should apply equally to the production of substrate and superstrate cells, should relate in particular to a simplification of the process with improved controllability and reproducibility of the production process. Furthermore, an extremely economical use of materials and a safe separation of the individual layers should be achieved with complete insulation of the individual solar cells. An improvement in the cost-effectiveness of the manufacturing process should also be derived from these aspects. In addition, the basic task of a desired solar module optimization is to be implemented, in particular also by means of suitable shapes and measures, in particular also in connection with concentrator modules, in the case of solar modules produced by the method according to the invention, which should result in particular application flexibility.

The solution to the above-mentioned complex of tasks for the production of thin-film solar cells in the substrate type can be found in claim 1, and for thin-film solar cells in the superstrate type in claim 2. The methods of the two claims correspond largely with the difference that the method according to claim 2 is, as it were, the inverse method to the method according to claim 1. This is understandable insofar as substrate and superstrate solar cells have the same basic structure with an inverse layer sequence.The substrate acts as the lower support layer and the light falls into the solar cell from above, whereas the superstrate acts as the upper support layer and the light incident through the superstrate However, in order to be able to structure the description clearly, the advantages of the invention should first be explained in more detail using the method according to claim 1, especially since they also result in the inverse method according to claim 2. This is followed by a brief explanation of the differences between the two Method.

The inventive method according to claim 1 enables a continuous structuring of all functional layers with an extremely low structuring effort. The use of a mask, which can be in particular stripe-like, saves two structuring steps that are otherwise required. This is, on the one hand, the usual structuring of the Jerk electrode after application to the substrate or in the inverse process after application to the absorber layer In the invention, the jerk electrode is structured directly when coating with a corresponding metal layer with the mask in place. There is no loss of material, since the mask can be used further the method step of the otherwise customary, particularly critical subsequent structuring of the semiconductor absorber layer. This is also very advantageous in that it causes the problems that arise with the mechanical ode r In particular, cutting the absorber layer by cutting with laser beams avoids damage to the individual layers, imprecise layer boundaries and non-reproducible, converted layer states caused by laser radiation cannot occur

In the method according to the invention according to claim 1, the absorber layer is made exactly like the jerk electrode by using the mask structured. The integrated Senen wiring of the individual solar cells takes place through a simple but particularly effective process step. Before the absorber layer is applied to the substrate and mask, it is shifted laterally by a small amount, so that narrow overlap and undercover webs are formed, which are correspondingly contacted as a front electrode by the conductive front layer to be applied over the entire surface after the mask has been removed. In the area of the undercover webs, when the absorber layer is applied, the back electrode sections are completely enclosed on one side. An interruption of the absorber layer between the individual solar cells is achieved by the mask itself, so that no short-circuit currents can occur here. A recess in the absorber layer above the rear electrode sections on its other side is achieved in the area of the covering webs and is used for later contacting by the front electrode. Co-coating the mask in turn means that there is no loss of material, and at the same time the mask is also completely processed up to the absorber layer. After the mask has been removed and the transparent conductive front layer has been applied over the entire surface, only a single subsequent structuring step by mechanical or laser-assisted methods is required in the method according to the invention. In a separating area, which includes the covering webs and a part of the adjacent solar cell, the front layer is separated with the width of the separating web apart from the rear electrode, so that a correspondingly structured front electrode is formed without short circuits between the individual solar cells. Conversion processes in the absorber layer to form conductor bridges, which are difficult to control, are eliminated. The position of the separation points is also not critical since they only have to be offset laterally in the area of the covering webs or in the direction of the adjacent solar cell. It is important for the location of the separation points to avoid short circuits between the back and front electrodes. This is guaranteed when cutting in the area of the active solar cell. The method according to claim 1 for the production of substrate solar cells basically corresponds to the method according to claim 2 for the production of superstrate solar cells, the process steps being carried out in the reverse order. However, since the transparent conductive front layer for the front electrode on the superstrate is not as mechanically stable in superstrate cells as the metal layer for forming the back electrode on the substrate in the case of substrate cells, the mechanical separation step for structuring the front electrode cannot be carried out in the same way in the production of superstrate cells (The scoring would take place down to the superstrat). Therefore, in the method according to claim 2, the entire transparent superstrate is first covered with a conductive front layer. After the mask has been fixed, the structuring is then carried out by scratching along the full areas of the mask as on a ruler, so that the mask lies with one of its lateral edges directly next to the structuring trenches. The absorber layer is then applied and the structuring trenches are likewise filled with absorber. After the mask has been moved laterally, the corresponding overlapping and undercovering bars are created again. After the application of the metal layer for structuring the back electrode, which can also be designed as p-TLO, the mask, which is now also covered with a complete solar cell structure, is finally removed. The main differences from the process sequence according to claim 1 can thus be seen in the advanced structuring step and in the later removal of the mask.

In the manufacturing processes according to the invention, particular attention is paid to the design of the mask. Until now, series-connected solar cells have consistently been built in an alternating strip-like manner, and design measures can be incorporated into the invention. Almost any geometric pattern, such as zigzag or wave-like patterns as well as lettering or company logos, can be carried out by observing two simple Boundary conditions are implemented. On the one hand, this is the basic character of the pattern, which must be composed of individual, smaller partial areas. This "digitization" of the analog pattern does not, however, restrict the optical function, since it is no longer possible from a distance is visible if it should not be a deliberately used element of the geometry pattern. When dividing the pattern into small sub-areas, the second boundary condition is to calculate their size so that the empty areas and possibly also the full areas in the geometry pattern have approximately the same area Avoiding a current mixture that resulted in partial areas of different sizes A uniformity of the full areas is always required if - as explained below - the mask is also to be further processed into a complete solar cell, although the area of the full areas differs The second boundary condition does not pose a major problem in implementation, since it can easily be included in the solar module design

With the relatively free design of the required mask for the manufacturing process, a completely new aspect can now be integrated into the use of solar modules manufactured according to the invention. Because of their function, they are usually arranged in the visible area anyway. Now, solar modules manufactured with the method according to the invention can also be used as aesthetic design elements for Building facades and advertising media are used, which significantly increases their attractiveness for use.Usually, the geometric pattern will consist of rectangular and straight, narrow stripes.To ensure that they stick together in the mask, the mask can have connecting bridges on its edges. When applying the individual layers to produce the solar module, these can be used Connecting webs can then be arranged outside the respective carrier layer. If this is not the case, for example, for dimensioning reasons, or the geometry pattern is also required in its inside Connecting webs, in particular also to achieve sufficient mechanical stability, such webs then initially form additional short-circuit bridges in the process sequence. Depending on the complexity of the geometry pattern, it is therefore sensible after continuing the process according to the invention, after process step (1 8) or (2 8) to provide an additional method step (A) structuring short-circuit areas in the front layer caused by connecting webs in more complex geometric patterns

The individual coatings can with the generally known

Processes such as vapor deposition or cathode sputtering are carried out. The composition of the required layer package for a solar module produced in accordance with the invention in thin-film technology takes place depending on the materials used and the application cases. In particular, prior to the application of jerk or front electrodes according to process step (1 2) or ( 2 1) after a further continuation of the invention, the following additional method step can be provided (B) application of a barrier layer to form a diffusion barrier. This can be, for example, a Cr layer that prevents interdiffusion of, for example, Na. Furthermore, optionally after the application of the metal layer (1 3) or after structuring the front layer (2 4), the following additional method step can advantageously be provided. (C) Application of an adhesive and / or swelling layer to form an adhesion promoter. This can be, for example, a Na swelling layer (NaF) and / or an adhesion-promoting layer, for example made of ZnSe or ZnS. Finally, the absorber-forming coating can optionally be used and the application of the front layer, ie before process step (1 6) or (2 5), an additional process step can advantageously be added (D) applying at least one buffer layer to form a space charge zone. This layer can consist, for example, of CdS or also of ZnS Furthermore, depending on the later application of the finished solar module, if the manufacturing process according to the invention is continued, the use of transparent materials to form the sub- or superstrate layer and / or metal layer can be provided.This makes it particularly suitable for window and semi-transparent areas, which is a fact takes advantage of the fact that glass panes are generally used anyway as large substrates or superstrates for thin-film solar cells. The material for forming the transparent metal layer can be, for example, ZnO, SnO or ITO (Indium Tin Oxide), which, in addition to other layers Different doping can also be used to form the transparent, conductive front layer (TLO). Non-transparent metal layers, on the other hand, can consist of molybdenum, tungsten or another metal. To form the absorber layer, which is also non-transparent, finally According to another advantageous development of the method according to the invention, this can be characterized by the use of amorphous or polycrystalline or microcrystalline silicon, dependent on the carrier layer, of polykπstailinem CdTe or of chalcopyrite compounds of the general structure Ag _x Cuι χln _y Gaι _y S _z Se _{2 zw} Te _w als Semiconductor material, where x and y values between 0 and 1 and z and w values between 0 and 2 can assume such that the sum of w + z does not significantly exceed the value 2. The mask can consist of different materials that provide the required mechanical strength In order to form substrate cells, the mask can be designed as a metal mask. In principle, the mask is not required to be transparent, since it is covered by the opaque absorber layer. A transparent, but not necessarily metallic, mask can be used in the manufacture of superstrate cells if a separate use The mask is intended to be a positive ending. However, before such a mask, which consists of glass or process-based transparent plastic, for example, is detachably fixed on the superstrate, it must be provided with a transparent front electrode (TLO) on its top. This coating can, for example similar to the coating for the formation of the back electrodes in substrate cells.

The essential improvement and simplification of the method is achieved in the method according to the invention by using the mask which can be configured according to predetermined wishes and boundary conditions. As a result, a number of structuring processes can be omitted as separate process steps. In particular, the measure of lateral displacement of the mask saves two otherwise necessary scribing cuts. The measure of the lateral displacement is a placeholder for the undercovering of the electrode sections on the one side in order to provide access for the next coating here and for the overlapping on the other side in order to create a recess here from the next coating. The size of the shortfall and overlap is related to the overall dimensions of the structured solar cells and is intended to ensure a secure overlap on the one hand and a secure separation on the other. According to another method continuation, it is therefore advantageous if the method is characterized by a lateral displacement of the mask in the range of 0.1 mm. Such a shift is technically easy to implement and to ensure safely and does not require a major change in the process setup between the individual process steps.

The mask plays an important role in various aspects of the method according to the invention. Due to their direct co-processing, no material losses occur. Particularly in the case of masks with more complex geometric patterns, which result in a higher cost for the creation, it is useful to reuse the mask several times without having to reprocess it in the meantime. The layers applied in previous process runs with their only small amounts of material do not interfere. If the mask is finally no longer used, the applied material can be recycled which is of particular importance in large-scale productions. In addition to these and the advantages mentioned above, the mask also has the further advantage that it can also be used as a “positive” for its own configuration, separately from the large-area solar module that is configured as a “negative” of the mask shape , Therefore, overall, according to another embodiment of the method according to the invention, it is advantageous if it is characterized by repeated use or separate processing of the detached mask, the full areas of which are then to be designed with the same area. There is no difference in the procedure, the processing on the substrate or superstrate and the mask is identical in each case. Due to the fact that the mask can also be used, there is no loss of material at any process point, and the relatively cost-intensive materials are used optimally. Furthermore, the usability supports the aesthetic point of view, in which the geometric patterns, in particular company logos, can also be used as positive. In the case of less complex mask structures, the mask can also be used to create individual solar cells of simple geometry, which can be combined to form solar modules by means of an appropriate sene connection (see below). Overall, however, according to a further development of the invention, when determining the geometry, it should be noted that there is a geometrical, aesthetically and / or informally structured structuring of the individual solar cells in compliance with identical partial patterns in the empty areas and / or in the full areas. As a result, the solar cells on the negative as well as the solar cells on the positive each make an identical contribution to electricity, so that no electricity mixture is created. It is not necessary to have the same area between full and empty areas. Furthermore, additional design aspects according to a continuation of the invention can also be implemented in that the partial patterns have different colorations, the selected colors having to be able to be integrated into the photovoltaic process. 1 o

In addition to the aesthetic aspects in the case of solar modules which are produced by the method according to the invention, the optimizing aspects already mentioned at the outset with regard to maximizing performance and / or minimizing the area must also be taken into account. To this end, according to an embodiment of the solar modules produced in accordance with the invention of both types of support layer, they are particularly advantageous if they characterized in that a light-collecting concentrator module consisting of individual concentrators in the form of imaging or non-imaging optical elements is provided, which are matched in their arrangement to the arrangement of the individual solar cells. The use of concentrators enables a significant increase in the average and total energy conversion efficiency of a Solar module The optical elements can be, for example, lenses in conventional semi-convex or fresnel-like form or also prisms in conical or a Acting another geometric shape According to a next embodiment, it can further be provided that the solar module is encapsulated on its light incidence side by a transparent glass or plastic with or without a transparent cover plate and the concentrators are integrated in the glass or plastic or on the inside of the cover plate applied or ground into it. In particular, the application can be carried out by gluing. Structuring the outside, on the other hand, is disadvantageous, since this makes cleaning more difficult and weather influences and dirt can influence the collecting effect of the concentrators. The concentrators used can preferably have a geometric concentration factor C _g have, which is in a number range between 1 and 10 Such concentrator modules are known in principle and have already been extensively appreciated in connection with the prior art, but especially in the Be Some interesting combinations are possible here for the solar modules produced by the method according to the invention. For example, according to another development of the inventive idea, it can be provided that the concentrator module is laterally spaced in front of the solar module 1 D

linear structured solar cells and is designed in the form of a blind, the individual slats of which are formed by linear concentrator lenses that can be tracked in parallel according to the position of the sun. Such designs are particularly suitable for an arrangement in the window area and here in particular, of course, in particularly sunny windows. This is also because the solar module itself can be made semi-transparent so that it already contributes to shading the interior. An advantageous further development of the solar blind can be characterized in that each concentrator lens is fixed at its two ends to two guide rods via two gift hanging points, which in turn run in guide slots in end blocks fixed in position with respect to the solar module and by simply pressing on movable wedge blocks are adjustable All lenses can be adjusted together. Furthermore, the concentrator lenses follow a path that ensures correct alignment with the solar cells in the event of different incidence of light.

In connection with the use of the mask as an independent solar cell carrier, it can also be provided in accordance with another embodiment that the solar module is formed from the mask and the electrodes of the individual solar cells are connected in series via an integrated, metallized contact strip be designed as a transparent, flexible contact film, the width of which corresponds to the entire width of the solar module. Furthermore, it can then be provided that the solar module is mounted in front of or behind (depending on the solar cell type) a further structured and integrated series-connected solar module, which is arranged in a stationary manner, and is laterally displaceably supported by a lateral winding or unwinding of the contact film which extends beyond the solar module, the lateral winding or unwinding is simultaneously designed as electrical polarization for the solar cell current. Depending on the position of the individual solar modules relative to one another, a choice can be made between maximum light transmission and maximum current production Such measures result in a partially transparent solar module with changeable shading, which can also be designed in particular from an aesthetic point of view. Seen as a whole. The optimal combination of aesthetic and functional design elements means that a solar module which has been produced by the method according to the invention and optionally modified to increase performance, therefore it should be provided that it is arranged individually or together with other solar modules in front of or in the window, facade or roof elements of a building or in the interior thereof. The degrees of transparency of the solar modules used can be adapted to those of the building surfaces and can be changed, for example fully transparent in front of shady windows and Glass components, semi-transparent in front of sunny windows and non-transparent in front of building walls, in the roof area or as sun protection. When using semi-transparent solar modules, the Use of concentrators, the area to be covered with solar cells is significantly reduced.This results in more flexibility for the architectural design.The small distance between the solar and concentrator modules allows ready-to-use offset pieces to be made for house building without significantly increasing the space required for conventional solar modules - All in all, completely new areas of application open up, which could make the use of solar modules - also in the interior - much more attractive. To avoid repetition of the modifications mentioned, reference is made to the following special description section for further details

The manufacturing method according to the invention and the forms of construction of solar modules produced therewith are explained in more detail below with the aid of the schematic figures for further understanding

1 shows the sequence of the manufacturing method according to the invention for a substrate cell, FIG. 2 shows the sequence of the manufacturing method according to the invention for a super cell,

3 shows a solar module made from substrate cells with a concentrator module using the method, FIGS. 4a, 4b shows a solar module made from substrate cells with a concentrator module in the form of a blind in two positions,

5a, 5b a solar module made with the method from substrate cells with variable shading in plan view and in section and

Figure 6 is a diagram of the effect of the concentrator modules.

In FIG. 1, the method according to the invention is shown in cross section on the basis of selected manufacturing states of an embodiment of a solar module to be manufactured. In a first method step (1.1), a thin-layer mask 100 is produced which corresponds to the desired geometry while observing the specified boundary conditions. In the exemplary embodiment shown, this is a comb-like geometry with solid areas 101 and empty areas 102 of the same area. Connecting webs 103 in the geometry pattern lie outside the solar cell structure to be produced and are therefore not considered further. In a method step (1.2), the mask 100 is detachably fixed on a transparent substrate layer 104 made of glass. In a next method step (1.3), a metal layer 105 is applied to the substrate layer 104 and the fixed mask 100. This creates a strip-like structured back electrode 106 in the form of the empty areas 102 in the geometric pattern of the mask 100 on the substrate layer 104. A metal layer 105 is also deposited on the full areas 101 of the mask 100 in method step (1.3). In the subsequent method step (1.4), the mask 100 is laterally displaced over the strip-shaped back electrode 106 in the direction of the arrow, for example by an amount in the range of 0.1 mm At this point, it should be pointed out that the dimensions are distorted in favor of a clear representation. With the lateral displacement, narrow undercover webs 107 and narrow overlapping webs 108 are formed

In a next method step (1.5), a photovoltaically active, thin semiconductor layer 109, for example made of the chalcopyrite compound CulnS ₂ , is applied to the substrate 104 and the laterally displaced mask 100. As a result, an absorber layer 110 structured via the mask 100 is formed, which also extends to the covering bridge 107, but not to the covering bridge 108. As a result, the strip-like jerk electrode 106 in the region of the covering bridge 107 is enclosed by the semiconductor layer 109 and left free in the region of the covering bridge 108. In method step (1.6), the mask 100 is detached and removed then separated, but processed in parallel to a “positive solar module” and differs from the “negative solar module” only in that the substrate layer 104 is omitted, but is mechanically replaced by the mask 100. In the following method step (1.7), the Substrate 104 now also major When the mask 100 is cleared of the area and in the area of the covering web 108, a transparent, conductive front layer 111 is applied to the jerk electrode 106 and, if necessary, separately from the removed mask 100, through which a front electrode 112 is formed. The separated mask 100 is thus finished and formed an initially unconnected solar module 113 made of individual thin-film solar cells 114 in the form of the full surfaces 101 of the geometric pattern without its connecting webs. The solar module can be carried out by subsequent suitable interconnection measures, which are relatively simple and integrated due to the missing substrate layer 104 and the exposed metal layer 105 113 can then be completed (analogously in FIGS. 3 and 5). In the installed state, the light is incident in the direction of the arrow 104 on the substrate 104 On the “negative” solar module 115, the front electrode 112 is initially unstructured and connects all the solar cells 116 in an electrical short circuit. In a subsequent method step (1.8), the front layer 111 is therefore separated in separation areas 119 of the covering webs 108 by a suitable scribing method, for example using a laser beam , separated with short-circuit-canceling separating webs 117 down to the strip-like back electrode 106. This generally shows a much better adhesive behavior on the substrate layer 104 than the absorber layer 109. As a result, the solar cells 116 are integrated electrically connected in series, the individual absorber layer strips 118 remaining electrically insulated. The solar module 115 is now complete and ready for use.

The method according to the invention for producing superstrate cells is shown analogously in FIG. In a first method step (2.1), a thin mask 150 is again provided according to a predefined geometry pattern. If later use of the mask as an independent solar module is planned, it consists of a transparent material and is provided on its top with a separately applied front electrode, not shown in the figure. In a subsequent method step (2.2), a transparent, conductive front layer 152 is applied to a superstrate 151 to form a front electrode 153. In the selected embodiment, this consists of several SnO layers of different doping (ITO or ZnO also possible). The mask 150 is then detachably fixed on the front layer 152 (method step (2.3)). Thereafter, in a method step (2.4), the front layer 152 is scanned along the outer edges of the mask 150, which act as mechanical or optical guide rulers, for structuring the front electrode 153. In a next method step (2.5), a semiconductor layer 154 is formed to form a layer corresponding to the Mask geometry applied structured absorber layer 155. Thereafter, the mask 150 in the process step (2.6) analogously to the process described above, shifted laterally by a small amount of approx. 0.1 mm. Cover webs 156 and undercover webs 157 are formed. In the subsequent process step (2.7), these are also covered with a metal layer, just like the scratched structural trenches 158 159 for structuring a jerk electrode 160 covered In the last process step (2.8), the mask 150 is then removed again. The solar module 161 is finished with a corresponding structuring and integrated serene connection between the individual thin-film solar cells 162. In the installed state, the incidence of light then takes place in the wrong direction Superstrat 151 through

After the description of the two analog processes for the production of substrate or superstrate cells, solar modules produced with the processes are to be explained in more detail below, in particular in connection with the use of concentrator modules.Here, the substrate cell type is consistently assumed.Here, however, it should be explicitly noted at this point that all embodiments after appropriate, common technical adjustment, can also be carried out with super cells

In FIG. 3 (reference symbols which are not further explained here and in the following figures, the meaning of which can be seen in FIG. 1 or the previous figure in each case) shows a solar module 200 produced by the method according to the invention in a partially transparent embodiment with laterally structured solar cells 201 on one Transparent substrate 202 and with a light-collecting concentrator module 203 as an integrated light concentration. Such a solar module 200 can be used, for example, as a window or as an element for architecturally demanding facades. An encapsulation that every standard thin-film solar module requires in order to be insensitive to weather influences is in the selected exemplary embodiment by a housing 204, which is also the Discharge of the generated electrical current is used, and realized a front glass plate 205, which is backfilled with a transparent plastic 206 filling the space (eg epoxy or synthetic resin). The concentrator module 203 is arranged on the inside 207 of the front glass plate 205 and has individual concentrators 208, which are matched in their arrangement to the arrangement of the individual solar cells 201. In the selected exemplary embodiment, these are strip-shaped, semi-convex lenses which are glued to the inside of the glass plate 205. To explain the effect of the concentrators, reference is made to FIG. 6.

FIG. 4 shows the embodiment of a partially transparent solar module 300 with rectilinearly structured solar cells 301 on a transparent substrate 302 and with a concentrator module 303 in the form of a “solar blind” made of trackable, linearly focusing concentrator lenses 304. The solar cells 301 are mounted behind the separately suspended, louvre-like concentrator module 303. This consists of as many lamella-like, linearly focusing concentrator lenses 304 as there are strip-shaped solar cells 301 in the solar module 300. Each concentrator lens 304 is attached to two at its two ends via two gifted suspension points 305 Fixed guide rods 306, which in turn run in guide slots 307 in end blocks 308. The position of the end blocks 308 is fixed with respect to the solar module 300, whereby a single adjustment of the concentrator lenses 304 is not necessary. The guide rods 306 become in the guide slots 307 ch simple pressure of movable wedge blocks 309 adjusted. As a result, the concentrator lenses 304 follow a path that ensures correct adjustment with respect to the solar cells 301 in the event of different incidence of light. The incidence of light is indicated by dashed light beams 310 for two different angles of incidence in the upper (a) and lower (b) of FIG. 4. First, it should be noted that this type of light concentration is particularly suitable for superstrate cells, where the integration of the concentrators into the solar module is based Difficulties arise, and secondly, that the described type of suspension not only correctly tracks the angle of inclination of the concentrator lenses 304, but also their center of gravity. The control signal for the tracking can be obtained in a simple manner from the current draw of the solar cells 301. In this exemplary embodiment the shape of the lateral structuring of the solar cells 301 should be straight, so that correct illumination by the concentrator lenses 304 is ensured. However, depending on the desired geometric concentration ratio, the scanning ratio solar cell clearance can also be selected differently than 2 1

FIG. 5 shows a partially transparent, laterally structured combination solar module 400 with variable shading, top (a) in plan view, bottom (b) in cross section. The combination solar module 400 consists of a stationary solar module 401, which has rigid solar cells 402 a transparent substrate 403 is constructed, and from a portable solar module 404 arranged above the stationary solar module 401, which is implemented on a strip-like mask 405. Solar cells 406 prepared on the mask 405 are provided by a flexible, transparent contact film 407 between the front and rear sides of the strip-shaped solar cells 406 electrically connected in series with one another. The contact sheet 407 is metallized over a large area with a transparent, conductive oxide. As a result, the contact sheet 407 can be designed over the entire width of a window, so that on the one hand there is less loss of sense resistance and on the other hand an increased mechanical Stability of the flexible solar module 404 results in the connecting contact foil 407 being wound at the ends on a cylindrical body 408, which also acts as an electrical supply to the outside.The cylindrical body 408 is suspended in a frame element 409 and can be rotated from the outside, so that the flexible Solar module 404 are moved sideways. As a result, the stationary solar module 401 is optionally shaded on the glass substrate 403, as a result of which Windows become semi-transparent overall with lower electricity production. Otherwise, the portable solar cells 406 are positioned between the rigid solar cells 402 of the fixed solar module 401, making the window completely opaque and maximizing power production. In addition to this exemplary embodiment, the solar cells 402, 406 do not necessarily have to be structured as straight strips, but they can also be structured according to aesthetic aspects, as long as their surfaces correspond to the general boundary conditions and are additionally congruent for this application. At this point, it should also be noted that when using super cells, the portable solar cells would have to be arranged below the stationary solar cells.

The concentrators will only allow a low light concentration due to the relatively short distance to the solar cells in the selected exemplary embodiments, which nevertheless brings about a decisive improvement in the average efficiency for thin-film solar cells. FIG. 6 shows a typical measurement curve of the efficiency of a chalcopyrite solar cell as a function of the light concentration, based on which three characteristic statements can be made:

1. The mean spectral irradiance on a summer day at noon is internationally approximated by the AM1.5 global spectrum according to IEC standard 904-3 (1989). In our latitudes there are lighting conditions in which the light intensity can vary by up to a factor of ten between summer and winter on the one hand and due to changing cloudiness on the other. For this reason, the solar cell is exposed to an irradiance of around 10% -100% of that expected globally according to AM 1.5.

2. The energy efficiency η of thin-film solar cells related to the radiation intensity varies in such a way that the operation at lower irradiance is unfavorable. Thus, in the solar cell shown in FIG. 5, an energy efficiency of η = 9.2% is measured when irradiating with AM 1.5 globally (C = 1), but with 10% of this irradiation (C = 0.1) only an energy efficiency of η = 6.5% , The optimal efficiency of this solar cell, η = 9.5%, is only achieved at a concentration of C = 2-3.

3. The use of light concentrators with low geometric concentration factors C _g shifts the irradiance to be expected during operation into a range that is favorable for thin-film solar cells. FIG. 6 shows three possible concentration factors C _g = 1, 3, 6 and it is clear that with a light incidence of 10% - 100% of the standard sun AM1 .5 globally, the average energy efficiency is 6 _g light concentration with C _g = 6 this typical solar cell always remains larger than η = 8.8%, ie over 90% of the maximum efficiency of 9.7% that can be achieved with this cell. With increasing optimization of the solar cell properties (lowering the series resistance), a shift of the maximum towards higher concentrations is to be expected.

Overall, it is therefore favorable to use concentrators which have a geometric concentration factor C _g in a number range between 1 and 10. In most cases, a geometric concentration C _g = 6 is already sufficient to ensure optimal efficiency. This low value makes the use of inexpensive plastic Fresnel lenses for chalcopyrite cells particularly interesting. A solar cell of a typical size of 0.5 to 5 cm ^{2 is} not brought exactly into the focal point of the Fresnel lens, but about 0.5 cm in front, so that the illumination of the solar cell is homogeneous. Further measures to increase the concentration, for example in the production of expensive secondary concentrators, as are necessary for Si or GaAs cells, are not necessary for amorphous and polycrystalline or microcrystalline solar cells. LIST OF REFERENCE NUMBERS

100 mask

101 full area

102 empty space

103 connecting bridge

104 substrate layer

105 metal layer

106 back electrode

107 shortage

108 cover bridge

109 semiconductor layer

110 absorber layer

111 front layer

112 front electrode

113 unconnected solar module,

114 unconnected thin-film solar cells

115 solar module

116 solar cell

117 separator

118 absorber layer strips

119 separation area

150 mask

151 Superstrat

152 front layer

153 front electrode

154 semiconductor layer

155 absorber layer

156 cover bridge

157 shortage 158 structuring trenches

159 metal layer

160 back electrode

161 solar module 162 thin-film solar cell

200 solar modules

201 laterally structured solar cell

202 transparent substrate 203 concentrator module

204 housing

205 glass plate

206 transparent plastic

207 inside 208 concentrator

300 solar module

301 solar cell

302 transparent substrate 303 concentrator module

304 concentrator lens

305 suspension point

306 guide rod

307 guide slot 308 end block

309 wedge block

310 light beam

400 combination solar module 401 fixed solar module

402 rigid solar cell

403 transparent substrate Zo

404 portable solar module

405 mask

406 flexible solar cell

407 contact foil 408 cylindrical body

409 frame element

Claims

claims

1. A method for producing a solar module (1 15) with structured and integrated thinned layer solar cells (1 16) as

Substrate cell type, characterized by the process steps

(1.1) providing a thin-layer mask (100) according to a predetermined geometric pattern of full surfaces (101) with integrated empty surfaces (102) that are identical to one another, (1.2) detachable fixing of the mask (100) on a substrate (104) as a carrier layer,

(1.3) applying a metal layer (105) for structuring a jerk electrode (106) in the form of the empty surfaces (102) in the geometric pattern of the mask (100), (1.4) laterally shifting the mask (100) over the structured jerk electrode (106) Formation of narrow cover webs (108) in the direction and undercover webs (107) against the direction of the displacement,

(1.5) Application of a photovoltaically active thin semiconductor layer (109) made of amorphous or polycrystalline or microcrystalline semiconductor material

Formation of a structured absorber layer (1 10),

(1.6) removing and removing the mask (100),

(1.7) Applying a transparent, conductive front layer (1 1 1) from at least one layer to form a front electrode (1 12) and (1.8) structuring the front layer (111) in separation areas (119) of the covering webs (108) with short-circuit canceling Separators (1 17) down to the metal layer (105) of the jerk electrode (106)

2. Method for producing a solar module (161) with structured and integrated thin-film thin-film solar cells (162) as a superstrate cell type, characterized by the method steps

(2.1) providing a thin-layer mask (150) according to a given geometry pattern from full surfaces with integrated empty surfaces that are identical to one another,

(2.2) applying a transparent, conductive front layer (152) from at least one layer on a superstrate (151) as a carrier layer to form a front electrode (153), (2.3) detachable fixing of the mask (150) on the transparent superstrate layer (151),

(2.4) structuring the front layer (152) along the full surfaces in the geometric pattern of the mask (150) down to the superstrate layer (151),

(2.5) Application of a photovoltaically active, thin semiconductor layer (154) made of amorphous or polycrystalline or microcrystalline semiconductor material

Formation of a structured absorber layer (155),

(2.6) lateral displacement of the mask (150) over the structured absorber layer (155) over to the formation of narrow covering webs (156) in the direction and undercover webs (157) against the direction of the displacement,

(2.7) applying a metal layer (159) for structuring a jerk electrode (160) in the form of the empty surfaces in the geometric pattern of the mask (150) and

(2.8) Removing and removing the mask (150)

3. The method according to claim 1 or 2, characterized by the method step (1.8) or (2.8) following additional method step depending on the complexity of the geometry pattern

(A) Structuring short-circuit areas in the front layer caused by connecting webs (103) in more complex geometric patterns

(1 1 1, 152)

4. The method according to any one of claims 1 to 3, characterized by the additional method step following the method step (1.2) or (2.1)

(B) applying a barrier layer to form a diffusion barrier.

5. The method according to any one of claims 1 to 4, characterized by the additional method step following the method step (1.3) or (2.4)

(C) applying an adhesive and / or swelling layer to form an adhesion promoter.

6. The method according to any one of claims 1 to 5, characterized by the additional method step preceding the method step (1.6) or (2.5)

(D) applying at least one buffer layer to form a space charge zone.

7. The method according to any one of claims 1 to 6, characterized by the use of transparent materials to form the sub- or superstrate layer and / or metal layer (104; 151/105; 159).

8. The method according to any one of claims 1 to 7, characterized by a support layer-dependent use of amorphous or poly- or microcrystalline silicon, polycrystalline CdTe or chalcopyrite compounds of the general structure AgχCu _-x lnyGa-ι _-y S _z Se _2-z ..wTew as semi-conductor material to form the absorber layer (1 10), where x and y values between 0 and 1 and z and w values between 0 and 2 can assume such that the sum of w + z does not significantly affect the value 2 exceeds.

9. The method according to any one of claims 1 to 8, characterized by the use of transparent materials for the production of the mask (150).

10. The method according to any one of claims 1 to 9, characterized by a lateral displacement of the mask (100; 150) in the range of 0.1 mm.

11. The method according to any one of claims 1 to 10, characterized by a repeated use or a separate further processing of the detached mask (100; 150), the full surfaces of which are then to be designed to be flat.

12. With the method according to any one of claims 1 to 1 1 manufactured solar module with structured and integrated senenverschalten solar cells, characterized in that a geometrical, aesthetic and / or informal viewpoint-oriented structuring of the individual solar cells in compliance with flat partial patterns each in the empty areas (102) and / or in the full areas (101).

13. Solar module according to claim 12, characterized in that the partial patterns have different colors, the selected colors must be able to be integrated into the photovoltaic process

14. Solar module according to claim 12 or 13, characterized in that a light-collecting concentrator module (203; 303) from individual concentrators (203; 304) in the form of imaging or non-imaging optical elements is provided, which in their arrangement on the arrangement of the individual solar cells (201; 301) are matched.

15. Solar module according to claim 14, characterized in that this (200) is encapsulated on its light incidence side by a transparent glass or plastic (206) with or without a transparent cover plate (205) and the concentrators (208) in the glass or Plastic (206) integrated or applied to the inside (207) of the cover plate (205) or ground into it.

16. Solar module according to claim 14 or 15, characterized in that the concentrators (208; 304) have a geometric concentration factor C _g , which is in a number range between 1 and 10.

17. Solar module according to one of claims 12 to 16, characterized in that the concentrator module (303) is arranged at a distance in front of the solar module (300) with laterally rectilinear structured solar cells (301) and is in the form of a blind, the individual lamellae of linear concentrator lenses (304) are formed, which can be adjusted in parallel according to the position of the sun.

18. Solar module according to claim 17, characterized in that each concentrator lens (304) is fixed at both ends via two gift hanging points (305) to two guide rods (306), which in turn are in guide slots (307) in opposite to the solar module ( 300) end blocks (308) fixed in position and can be adjusted by simply pressing on movable wedge blocks (309).

19. Solar module according to one of claims 12 to 18, characterized in that the solar module (404) is formed from the mask (1 10) and the electrodes (106, 1 12) of the individual solar cells (406) via an integrated, metallized contact strip are connected in series.

20. Solar module according to claim 19, characterized in that the contact strip is designed as a transparent, flexible contact film (407), the width of which corresponds to the entire width of the solar module (400).

21. Solar module according to claim 20, characterized in that the solar module (404), depending on the type of solar cell, in front of or behind a further structured and integrated antenna-connected solar module (401), which is arranged in a stationary manner, and via a lateral winding or unwinding (408) the contact foil (407), which extends beyond the solar module (404), is laterally displaceably mounted, the lateral winding or unwinding (408) being simultaneously designed as electrical polarization for the solar cell current.

22. Solar module according to one of claims 12 to 21, characterized in that it is arranged individually or together with other solar modules (200; 300; 400) in front of or in window, facade or roof elements of a building or in the interior thereof.