Thin-film solar module with serial cell interconnection and manufacturing process

Abstract

Thin-film solar module with - a solar cell array (1) comprising a plurality of solar cells (2) with a layer structure comprising a back contact layer (3), a front contact layer (4) and an absorber layer (5) between the back contact layer and the front contact layer, and - an electrical connection structure for electrically connecting adjacent solar cells (21, 22, ...) in series, wherein the connection structure contacts the back contact layer of a first solar cell (21) on a side (3a) facing the absorber layer and the front contact layer of a solar cell (22) in a series connection direction (R S ) to the second solar cell (22) adjacent to the first solar cell on a side (4b) facing away from the absorber layer, wherein - a separation trench (6) extends continuously through the front contact layer (4), the absorber layer (5) and the back contact layer (3) and separates the first and the second solar cell (21, 22) from each other, - the first solar cell (21) has at least one contact opening (7) which extends through the front contact layer (4) and the absorber layer (5) to the back contact layer (3), and - the electrical connection structure comprises at least one electrical connection element (8) extending across the separation trench, which on the one hand contacts the front contact layer (4) of the second solar cell (22) on the side (4b) facing away from the absorber layer and on the other hand extends into the contact opening (7) of the first solar cell and there contacts the back contact layer (3) of the first solar cell on the side (3a) facing the absorber layer, wherein the electrical connection element is electrically insulated in the contact opening from the absorber layer and the front contact layer of the first solar cell and, if the contact opening is arranged at a lateral distance from the separation trench, extends in a region (15) between the contact opening and the separation trench above the front contact layer of the first solar cell, and wherein - the electrical connecting element comprises a bond wire element (12) comprising an electrically conductive bond wire piece (12a) and an electrically insulating sheath (12b) surrounding it, or comprising a bond wire (12c) coated with a thermoplastic material or adhesive material (19), or - an electrical insulation layer structure (14) is provided which surrounds a material deposition element in the contact opening circumferentially and is additionally located in the separation trench and which electrically separates the material deposition element from the underlying front contact layer of the first solar cell in the area between the contact opening and the separation trench when the contact opening is arranged at a lateral distance to the separation trench.

Description

[0001] The invention relates to a thin-film solar module with a solar cell array that includes a plurality of solar cells with a layer structure that comprises a back contact layer, a front contact layer and an absorber layer between the back contact layer and the front contact layer, and an electrical connection structure for electrically connecting solar cells arranged next to one another in series, wherein the connection structure contacts the back contact layer of a first solar cell on a side facing the absorber layer and contacts the front contact layer of a second solar cell adjacent to the first solar cell in a series connection direction on a side facing away from the absorber layer.

[0002] Thin-film solar modules of this type are known in many variations. The absorber layer functions as the photovoltaically active layer, while the front contact layer and the back contact layer serve as electrical connections for transporting the electrical charges generated and separated in the absorber layer by the photovoltaic effect. In addition to these three layers, the layer structure usually includes one or more further layers, such as a buffer layer, a barrier layer, etc., which are not of interest here and are therefore not mentioned separately. The solar cell array is usually implemented in a monolithic form.

[0003] The terms "front contact layer" and "back contact layer" refer both to the actual front contact layer and back contact layer, respectively, which are fully adjacent to the absorber layer, and to any additional electrical contact structures that may conventionally be provided on the side of the front contact layer or back contact layer facing away from the absorber layer, in order to facilitate the electrical connection of the solar cell array to the outside. As is customary, the front contact layer here refers to the one of the two electrical contact layers located on the side of the solar module or solar cell array that receives the light, i.e., facing the direction of the incident light.For this reason, the front contact layer typically consists of a highly electrically conductive, highly transparent material, usually a transparent, electrically conductive oxide material. A contact grid structure with contact fingers made of a highly electrically conductive, but opaque, metallic material is applied to this front contact layer. The contact grid structure, with its low ohmic resistance, is intended to ensure the most unimpeded and uniform charge and current transport possible across the surface of the solar cell array, while minimizing the reduction of the usable light-incidence area for the absorber layer.

[0004] The electrical connection structure allows adjacent solar cells of the solar cell array to be electrically connected in series, i.e., wired together. By appropriately designing the electrical connection structure, any number of solar cells in the array, up to and including all solar cells of the array, can be electrically connected in series. In certain thin-film solar module configurations, blocks of such serially connected cells from one array or from two separate arrays can often be connected in parallel.

[0005] In particular, integrated designs of the electrical interconnection structure are known in which the back contact layer of a solar cell is connected to the front contact layer of an adjacent solar cell by means of an interconnection or contact layer structure that is formed during the formation of the solar cell array by corresponding layer formation and layer structuring processes. This interconnection structure is usually formed simultaneously with the front contact layer and using the same layer material as the front contact layer, or it is applied directly to the front contact layer. In this case, a corresponding area of ​​the front contact layer of the back-contacted solar cell is short-circuited with its back contact layer and is electrically separated from the remaining, actually active, part of the front contact layer of this solar cell by the structuring.To produce this integrated electrical connection structure for serially interconnecting the solar cells, the so-called P1-P2-P3 structuring technique is commonly used, as described, among other things, in patent DE 199 34 560 B4 and in the textbook "Handbook of Photovoltaic Science and Engineering," 2nd edition, pages 585 to 587, ISBN 978-0-470-72169-8. Here, the rear contact layer is suitably structured by P1 lines, the absorber layer by P2 lines, and the front contact layer by P3 lines. Numerous special forms of this interconnection technique are also known; see, for example, the photovoltaic module disclosed in patent DE 199 34 560 B4.

[0006] For the P1-P2-P3 structuring technique, various process-simplifying variants have been proposed to minimize the number of required manufacturing steps, and in particular deposition and / or structuring steps. Examples include a so-called post-absorber formation process and a post-device fabrication process, as described in the journal article by C. Fredric et al., "Results of Recent CuInSe2 Module Investigations," IEEE PVSC 1993, page 437. These process variants utilize an insulating layer structure that, among other things, fills the cell-separating gaps. Connecting bridges for serial cell connection across the insulating layer structure in the gaps are formed from front contact layer material or another electrically conductive layer material.

[0007] In the journal article S. Haas et al., Innovative Series Connection Concept for Thin-Film Solar Modules, Proceedings of the 26 th European Photovoltaic Solar Energy Conference and Exhibition, p. 2375, proposes a modified P1-P2-P3 structuring technique with dot-like instead of line-like P2 structures that extend through the absorber layer to the back contact layer and are filled with front contact layer material that extends in a web-like manner over a cell-separating trench. With the exception of these web regions, this trench extends through the front contact layer, the absorber layer, and the back contact layer, providing the P1 line. Outside of these web regions, the P3 line is also formed by the trench; in the web region, it bypasses the P2 dot structure and the web region in a U-shape and extends through the front contact layer and the absorber layer.

[0008] As an alternative to the thin-film solar module type considered here, with front-side series connection of the solar cells, thin-film solar modules with rear-side series connection of the solar cells are also known. In these modules, the connection structures that electrically connect the front contact layer of a respective cell to the rear contact layer of an adjacent cell for series connection run along the rear of the module, viewed from the rear contact layer. Such thin-film solar modules are disclosed, for example, in US 2009 / 0050190 A1 and JP 2014-33239 A, as well as in German patent DE 69837143 T2.

[0009] A fundamental problem of thin-film solar modules of the type mentioned above is to lose as little photovoltaically active area, i.e. dead area, as possible through the structuring measures for the electrical connection of the front contact layer and the back contact layer to the outside and for the series connection of the solar cells.

[0010] The invention is based on the technical problem of providing a thin-film solar module of the type mentioned at the outset, which can be manufactured with comparatively little effort and requires only a relatively small dead area for the series connection of the solar cells, and an advantageous method for producing such a thin-film solar module.

[0011] The invention solves this problem by providing a thin-film solar module with the features of claim 1 or 2 and a manufacturing method with the features of claim 12. Advantageous embodiments of the invention are specified in the dependent claims.

[0012] In the thin-film solar module according to the invention, a separation trench extends continuously through the front contact layer, the absorber layer, and the back contact layer, separating the first and second solar cells from each other. The first solar cell has at least one contact opening that extends through the front contact layer and the absorber layer to the back contact layer. The contact opening can be arranged at a lateral distance from the separation trench or alternatively directly adjacent to it or laterally overlapping it.The electrical connection structure has at least one electrical connection element extending across the separation trench, which on the one hand contacts the front contact layer of the second solar cell on the side facing away from the absorber layer and on the other hand extends into the contact opening of the first solar cell and there contacts the back contact layer of the first solar cell on the side facing the absorber layer, wherein the electrical connection element is electrically insulated in the contact opening from the absorber layer and the front contact layer of the first solar cell and, if the contact opening is arranged at a lateral distance from the separation trench, extends in an area between the contact opening and the separation trench above the front contact layer of the first solar cell in an electrically insulated manner.

[0013] The invention thus advantageously enables the provision of a thin-film solar module that manages with a single line structuring of the layer structure consisting of back contact layer, absorber layer and front contact layer, including any additional intermediate layers or adjacent layers such as barrier or buffer layers, namely for forming the separating trench between each pair of adjacent solar cells to be connected in series.

[0014] The contacting of the rear contact layer by the electrical connecting element via the contact opening does not generally require a linear opening of the front contact layer and the absorber layer; rather, in accordance with the nature of a contact opening, a quasi-punctual rather than linear opening of the front contact layer and the absorber layer is sufficient to expose the rear contact layer in a corresponding punctual area in the manner of a contact spot or a through-contact opening, i.e. an opening extending through the layers in question to form a through-contact in this opening, which can therefore also be referred to as an opening for a contact passage or as a contact passage opening.A further related advantage of the thin-film solar module according to the invention is that not the entire front contact layer area of ​​the second solar cell between the separating groove and a spaced-apart contact line for contacting the back contact layer is lost, but only the front contact layer area that is removed for the contact opening, and possibly also the area over which the electrical connecting element extends from the contact opening to the separating groove, if this is not light-transparent. This significantly reduces the dead area compared to a conventional P1-P2-P3 structuring technique. For example, the dead area can be reduced to only about 15% to 20% of the dead area typical for conventional thin-film solar modules with P1-P2-P3 structuring technology for series connection of the solar cells.Specifically, in appropriate designs, the dead area can be limited to less than 1% of the module area. For optimal current transport behavior of the electrical connection element, it is generally advantageous if it has a substantially constant current-carrying cross-section along its longitudinal extent from the contact point with the back contact layer to the contact point with the front contact layer of the adjacent solar cell, or if this cross-section varies along its longitudinal extent by a maximum factor of one hundred, preferably a maximum factor of ten.

[0015] In a further development of the invention, a maximum dimension of a contact area of ​​the connecting element with the rear contact layer of the first solar cell in the contact opening is less than ten times a lateral distance of the contact opening to a contact point of the connecting element with the front contact layer of the second solar cell and / or less than one fiftieth of a total length of the separation trench, in particular less than one thousandth and preferably less than one twenty thousandth of the total length of the separation trench, wherein the total length of the separation trench is typically in the range between 1 cm and 6 m. This means a quasi-point contact of the rear contact layer of the first solar cell in the contact opening by the electrical connecting element, which further contributes to achieving a small dead area.Depending on requirements, the electrical connection element can extend laterally for a certain short length in the region of its contact surface to the back contact layer, i.e., parallel to the back contact layer plane or to the plane of the layer structure, or, alternatively, it can extend directly away from the back contact layer parallel to the longitudinal direction of the contact opening or toward it. The longitudinal axis of the contact opening preferably runs perpendicular to the plane direction of the layer structure and thus also to the back contact layer, i.e., in the plane normal direction of the layer structure, or alternatively, obliquely thereto.

[0016] In advantageous embodiments, this maximum dimension of the contact area of ​​the connecting element with the back contact layer of the first solar cell in the contact opening is less than five times or less than twice the lateral distance of the contact opening to the contact point of the connecting element with the front contact layer of the second solar cell. In further advantageous embodiments, this maximum dimension of the contact area of ​​the connecting element with the back contact layer of the first solar cell in the contact opening is smaller than this lateral distance of the contact opening to the contact point of the connecting element with the front contact layer of the second solar cell, wherein in corresponding realizations it can be, for example, at least three, five, seven, or ten times smaller than said lateral distance.

[0017] In alternative designs, for corresponding applications, it may be provided that the maximum dimension of the contact area of ​​the electrical connecting element with the back contact layer of the first solar cell is larger than the lateral distance of the contact opening to the contact point of the electrical connecting element with the front contact layer of the second solar cell.

[0018] In a further development of the invention, the electrical connecting element contacts the back contact layer of the first solar cell in the contact opening at a first contact point and the front contact layer of the second solar cell at a second contact point, which is arranged offset from the first contact point in a direction perpendicular to the series connection direction. This offset of the contact point of the electrical connecting element to the front contact layer of the second solar cell compared to its contact point with the back contact layer of the first solar cell in the contact opening can be advantageously used, for example, in manufacturing to attach the electrical connecting element in a so-called in-line manufacturing process by means of a device that moves transversely to the longitudinal direction of the separating trench during continuous feed of the module in a longitudinal direction, i.e., a feed direction parallel to the longitudinal direction of the separating trench.In alternative designs, the two contact points can be arranged, for example, at the same height with respect to the direction perpendicular to the series connection direction.

[0019] According to one aspect of the invention, the electrical connection structure comprises a plurality of electrical connection elements for electrically connecting the first and second solar cells in series, which are arranged electrically parallel and spaced apart from one another in a direction non-parallel to the series connection direction. This measure can be advantageous for improved electrical connection and connection of the serially connected solar cells by enabling current transmission or current collection for the serially connected solar cells via the plurality of electrical connection elements in several areas distributed over the extent of the respective solar cell. Depending on the system design, alternatively, just a single electrical connection element may be sufficient for serially connecting the two solar cells.

[0020] According to one aspect of the invention, the electrical connection structure has a plurality of electrical connection elements for electrically connecting the first and second solar cells in series, wherein several of the electrical connection elements contact the rear contact layer of the first solar cell in a same first contact opening and contact the front contact layer of the second solar cell at different second contact points. This measure of a fan-shaped connection of several electrical connection elements in a common contact opening for contacting the rear contact layer can, in corresponding applications, for example, contribute to dividing the current transport between the respective contact point of the rear contact layer of one solar cell and the front contact layer of the other solar cell over a larger area of ​​the front contact layer. This can, if necessary, for example,This is achieved by using a transparent conductive oxide material for the front contact layer, with comparatively low transverse conductivity and high transparency, i.e., permeability with respect to the light used by the absorber layer. In alternative designs, only a single electrical connection element extends from each contact opening.

[0021] According to one aspect of the invention, the electrical connection structure has a plurality of electrical connection elements for the electrical serial connection of the first and the second solar cell, wherein several of the electrical connection elements contact the front contact layer of the second solar cell at the same second contact point and contact the back contact layer of the first solar cell in different contact openings.This measure can be used, for example, to connect the contact points on the front contact layer, on the one hand, and on the rear contact layer in the contact openings, on the other, in a zigzag structure of the electrical connecting elements. In this structure, the electrical connecting elements extending from a respective contact point on the front contact layer lead to different contact points on the rear contact layer in the contact openings, and the electrical connecting elements extending from a respective contact opening for contacting the rear contact layer lead to different contact points on the front contact layer. Alternatively, only a single electrical connecting element extends from each contact point on the front contact layer.

[0022] According to one aspect of the invention, the electrical connection structure has a plurality of electrical connection elements for the electrical serial connection of the first and the second solar cell, wherein at least two of the electrical connection elements are formed from a one-piece manufactured connecting piece that contacts the back contact layer of the first solar cell at least in a first contact opening and contacts the front contact layer of the second solar cell at least at two different second contact points and / or contacts the back contact layer of the first solar cell at least at two different contact openings and contacts the front contact layer of the second solar cell at least at a second contact point.This measure can further reduce manufacturing effort in relevant applications by using a single connector to form multiple electrical connections, preferably, for example, a zigzag-shaped connection structure. In alternative embodiments, each electrical connection is formed individually.

[0023] In a further development of the invention, the electrical connection element contacts the front contact layer of the second solar cell at several serially successive second contact points. This measure can also be used to effect current transport between a contact point of the rear contact layer of one solar cell, on the one hand, and several spaced-apart contact points of the front contact layer of the other solar cell, on the other hand, and thus to distribute it over a larger area of ​​the front contact layer. This in turn favors, for example, the use of a transparent conductive oxide material with relatively low transverse conductivity and, in turn, relatively high light transparency for the front contact layer. Alternatively, the electrical connection element contacts the front contact layer only at a single contact point.

[0024] In a further development of the invention, the electrical connecting element contacts the front contact layer of the second solar cell on a front contact grid structure. This measure can improve the mechanical and electrical connection for the front contact layer in question compared to contacting the connecting element, for example, on a transparent conductive oxide material of the front contact layer. Often, high mechanical strength of the connection to a typically metallic material of the front contact grid structure, and in particular high adhesion, is easier to achieve than to a transparent conductive oxide material. The current transfer characteristics can also be improved in many cases. Alternatively, the electrical connecting element contacts the front contact layer directly without a front contact grid structure or outside of one.

[0025] In a further development of the invention, the electrical connecting element is formed integrally with a front contact grid structure of the front contact layer of the second solar cell. This can be advantageously used, for example, in manufacturing to form the electrical connecting element and the front contact grid structure simultaneously in a single manufacturing process.

[0026] According to one aspect of the invention, the electrical connecting element comprises a bonding wire element. This represents an advantageous way of realizing the electrical connecting element. The bonding wire element can consist of a bonding wire material known per se.

[0027] According to one aspect of the invention, the bonding wire element comprises an electrically conductive bonding wire piece and an electrically insulating sheath surrounding it. This measure advantageously prevents unintentional short circuits between the bonding wire piece and the front contact layer of the respective solar cell in the vicinity of the contact opening. The sheath can be formed, for example, by a sheath made of electrically insulating tubing that tightly or loosely surrounds the bonding wire piece, or by an electrically insulating surface coating of the bonding wire piece. In alternative embodiments, a bonding wire without an electrically insulating sheath is used if this is not required.

[0028] In one embodiment of the invention, the electrically insulating sheath is formed by a sheathing tube made of a transparent material. The use of this sheathing tube is easy to manufacture and functionally reliable. By making the sheathing tube from a transparent material, corresponding light losses can be avoided.

[0029] In a further embodiment of the invention, the electrically insulating sheath is formed by a sheathing tube that loosely surrounds the bonding wire piece at a radial distance in a central region and terminates at both ends with a constriction. The constriction can be achieved, for example, by a shrink-wrapping process known per se. The radial distance between the sheathing tube and the bonding wire piece in the central region provides sufficient clearance to compensate for or absorb any thermal stresses that may occur during manufacturing and operation of the module. In alternative embodiments, a constriction can be provided only at one of the two ends of the tube. Alternatively, a constriction can be provided in a central region of the tube, allowing a certain degree of freedom of movement or expansion of the bonding wire within the tube.

[0030] In a further embodiment of the invention, the electrically insulating encapsulation is formed by a sheathing tube that extends laterally on both sides beyond the separating groove in the series connection direction. Thus, in this case, the sheathing tube extends on both sides of the separating groove both towards the contact point with the front contact layer of one solar cell and towards the contact opening for contacting the back contact layer of the other solar cell.

[0031] In a further embodiment of the invention, the electrically insulating sheath is formed by a sheathing tube that extends into the contact opening or to a lateral distance from the contact opening of less than twenty times its tube wall thickness in the associated tube end region. It turns out that this is a favorable dimensioning measure for the extension of the sheathing tube along the bond wire section, whereby the sheathing tube reliably protects against unwanted short circuits and, at the same time, does not impede the electrical bond contact to the front contact layer of one solar cell or to the back contact layer of the other solar cell.

[0032] In a further embodiment of the invention, the electrically insulating sheath is formed by a sheathing tube that extends into the contact opening or to a lateral distance from the contact opening of less than five times its tube wall thickness in the associated tube end region. This represents a further advantageous dimensioning measure with the aforementioned effects.

[0033] According to one aspect of the invention, the bonding wire element comprises a bonding wire coated with a thermoplastic material or adhesive. This can advantageously contribute to a high adhesive strength of the contact between the bonding wire element and, in particular, the front contact layer. This is especially beneficial when the contact is made with a transparent conductive oxide material, such as the front contact layer. During the bonding process, the thermoplastic material or adhesive can melt and penetrate or adhere to the areas between the generally metallic wire material of the bonding wire and the front contact layer material, thereby increasing the bond strength. Suitable formulations for the adhesive include, for example, solvent-based formulations, multi-component formulations of binder and hardener, and formulations that cure under UV light.Alternatively, an uncoated bonding wire can be used.

[0034] In a further development of the invention, the electrical connecting element comprises a material deposition element. This represents another advantageous way of realizing the electrical connecting element. The material deposition element is an element formed by a material deposition process, e.g., an element formed by a printing technique such as screen printing, digital printing, etc., by vapor deposition, sputtering, dispensing, or the like.

[0035] According to one aspect of the invention, the thin-film solar module has an electrical insulation layer structure that circumferentially surrounds the material deposition element in the contact opening and, if the contact opening is arranged at a lateral distance from the separation trench, electrically separates it in the area laterally between the contact opening and the separation trench from the underlying front contact layer of the first solar cell. In the latter case, the insulation layer structure lies above the front contact layer in this area, and the material deposition element lies above the insulation layer structure. The material deposition element preferably does not completely cover the insulation layer structure up to the edges, but only to a proportion of, for example, between 10% and 90%, in each case with respect to a relevant linear dimension, such as, in particular, the width of the insulation layer structure.of the material deposition element transversely to the longitudinal extent from the contact opening to the adjacent, second solar cell. In other words, in this case, the material deposition element is set back slightly at its edges relative to the insulation layer structure. This helps to prevent any electrical short circuits that could result from the material deposition element laterally extending over the underlying insulation layer structure in this area. On the other hand, the dimensions of the material deposition element are kept sufficiently large to achieve the desired current transmission capacity. In the alternative design, in which the contact opening is directly adjacent to the separation trench laterally without any gap, or...Because the material deposition element overlaps laterally, it does not need to extend over the underlying front contact layer of the first solar cell. Instead, it can be guided directly from the contact opening across the separation trench to the front contact layer of the adjacent, second solar cell, and therefore does not require electrical insulation from it. The electrical insulation layer structure is then only needed for the sleeve-like insulation of the material deposition element in the contact opening and, if necessary, for flank insulation in the separation trench towards the adjacent, second solar cell. However, it can optionally also be provided on an area of ​​the upper surface of the front contact layer in this case.In any case, the electrical insulation layer structure ensures, in a manufacturing-wise and functionally advantageous manner, that the material deposition element is protected from unwanted short circuits, particularly to the front contact layer of the solar cell whose back contact layer is in contact with the material deposition element. Depending on requirements and application, the electrical insulation layer structure can be located only in areas adjacent to the material deposition element or also in other areas where electrical insulation is desired or required.

[0036] According to one aspect of the invention, the electrical insulation layer structure is additionally located in the separation trench. This measure has the advantage that the separation trench can be filled with the same electrical insulation layer structure that serves as short-circuit protection for the material deposition element. It turns out that in corresponding applications, this can advantageously support the electrical isolation of adjacent solar cells by means of the separation trench.

[0037] In a further development of the invention, the current-carrying cross-section of the electrical connecting element is essentially constant or varies by a maximum factor of one hundred, preferably a maximum factor of ten, along its longitudinal extent from the contact point with the back contact layer to the contact point with the front contact layer of the adjacent solar cell. This can contribute to optimal current transfer behavior of the electrical connecting element.

[0038] In a further development of the invention, the lateral dimension of the electrical connecting element in the contact opening lies in the range between 10% and 90% of the lateral dimension of the contact opening. This represents a good balance between the lateral dimension of the electrical connecting element on the one hand and the lateral

[0039] Dimension of the surrounding area of ​​the contact opening, in which, for example, the electrical insulation layer structure can be located.

[0040] In a further development of the invention, the material deposition element extends over the electrical insulation layer structure at a lateral distance from an edge of the electrical insulation layer structure and covers the electrical insulation layer structure to a proportion between 10% and 90% with respect to a given direction of extension. This can be advantageous for preventing short circuits between the material deposition element and the underlying front contact layer and simultaneously ensuring sufficient current-carrying capacity.

[0041] In a further development of the invention, the ratio of the lateral width of the separating trench to the lateral wall thickness of the electrical insulation layer structure in the contact opening is between 100:1 and 1:100, in particular between 10:1 and 1:10, and preferably substantially 1:1. This can be conducive to good electrical insulation of adjacent solar cells.

[0042] In the manufacturing method according to the invention, the layer structure comprising the rear contact layer, the absorber layer, and the front contact layer is first formed on a module substrate. Then, the separation trench is formed through the front contact layer, the absorber layer, and the rear contact layer to separate the layer structure into at least the first and second solar cells. Subsequently, the at least one contact opening is formed in the first solar cell through the front contact layer and the absorber layer to the rear contact layer. Thereafter, the electrical connection structure is formed with the at least one electrical connection element, which extends between the front contact layer of the second solar cell and the rear contact layer of the first solar cell, across the separation trench, and into the contact opening.

[0043] This approach allows the manufacturing effort for the thin-film solar module to be kept comparatively low, and this manufacturing process enables the realization of a thin-film solar module with a particularly small dead area. Compared to a conventional P1-P2-P3 structuring, according to the invention, the line structuring for the separation trench can replace the P1 and P3 line structuring, and the structuring of the at least one contact opening can replace the P2 line structuring.

[0044] In a further development of the invention, to produce a thin-film solar module with the material deposition element, the electrical insulation layer structure is formed after the formation of the at least one contact opening and before the formation of the electrical connection structure, with at least partial filling of both the separation trench and the contact opening. Simultaneously or subsequently, a through-hole is provided through the electrical insulation layer structure in the contact opening. The simultaneous provision of the through-hole can be achieved, for example, by filling the respective contact opening not completely, but in a ring shape with the material of the insulation layer structure, so that the through-hole remains inside the ring shape. The sequential provision of the through-hole can be achieved, for example,This is achieved by creating the through-hole in the contact cavity, which is completely filled with the insulating layer material, using a laser beam drilling process or a photo-etching process. The corresponding electrically conductive material can then be introduced into the through-hole during the subsequent formation of the electrical connection structure, e.g., by means of a deposition process or a printing or spraying process, such as a digital printing or inkjet printing process, or a dispensing process. If residues or deposits are present in the through-hole during laser beam drilling, e.g.,If pyrolysis products of the insulating material remain, the electrical connection structure in the contact opening may not form a single-strand electrical conductor, but rather exhibit a fractal structure, and / or the exposed back contact layer may not make full contact. However, this is not problematic as long as it fulfills its required electrical connection function. Therefore, the thin-film solar module with the material deposition element(s) can be manufactured with comparatively little effort.

[0045] Advantageous embodiments of the invention are illustrated in the drawings. These and further advantageous embodiments of the invention are described in more detail below. The drawings show: Fig. 1 a partial schematic plan view of a thin-film solar module with a solar cell array with several electrically serially connected solar cells and associated electrical connection structure, here with bonding wire elements, Fig. 2 a schematic longitudinal section view along a line II-II in Fig. 1, Fig. 3 the view of Fig. 1 for a variant of the electrical connection structure, Fig. 4 the view of Fig. 2 for the version variant of Fig. 3, Fig. 5 the view of Fig. 1 for another variant of the electrical connection structure, Fig. 6 a detailed view of area VI in Fig. 3, Fig. 7 a schematic detailed sectional view of an area VII in Fig. 5, Fig. 8 the view of Fig. 7 for the variant of Fig. 3, Fig. 9 a view accordingly Fig. 1 for another variant of the electrical connection structure, Fig. 10 the view of Fig. 9 for another variant of the electrical connection structure, Fig. 11 a view accordingly Fig. 1 for another variant of the electrical connection structure, Fig. 12 the view of Fig. 11 for another variant of the electrical connection structure, Fig. 13 the view of Fig. 11 for another variant of the electrical connection structure, Fig. 14 a microscopic-schematic longitudinal section view in a bond contact point area XIV in Fig. 11, Fig. 15 a view accordingly Fig. 1 to illustrate another variant of the electrical connection structure, here with material deposition elements, Fig. 16 a longitudinal section view along a line XVI-XVI in Fig. 15, Fig. 17 a partial detail view of area XVII in Fig. 15 for one version variant, Fig. 18 a partial detail view of area XVIII in Fig. 16 for the version variant of Fig. 17, Fig. 19 the view of Fig. 16 for a further design variant in a first manufacturing stage of the module after forming separation trenches and contact openings, Fig. 20 a partial view of an area XX in Fig. 15 for the version variant of Fig. 19 in the first stage of production, Fig. 21 the view of Fig. 19 in a second manufacturing stage after forming an electrical insulation layer structure, Fig. 22 the view of Fig. 20 in the second manufacturing stage of Fig. 21, Fig. 23 the view of Fig. 21 in a third manufacturing stage after forming through-contact openings, Fig. 24 the view of Fig. 22 in the third manufacturing stage of Fig. 23, Fig. 25 the view of Fig. 23 in a fourth manufacturing stage after forming the electrical connection structure, Fig. 26 the view of Fig. 24 in the fourth manufacturing stage of Fig. 25, Fig. 27 a view accordingly Fig. 15 for a version variant with integrated front contact grid structure, Fig. 28 the view of Fig. 27 for a variant of the integrated front contact grid structure, Fig. 29 the view of Fig. 27 for a further variant with integrated front contact grid structure, Fig. 30 a partial view of Fig. 13 for a further variant with metal deposition elements and integrated front contact grid structure, Fig. 31 the view of Fig. 30 for a further variant with metal deposition elements and integrated front contact grid structure, Fig. 32 the view of Fig. 13 for a further variant with metal deposition elements and integrated front contact grid structure, Fig. 33 the view of Fig. 19 limited to an area of ​​two adjacent solar cells for a variant with a contact opening laterally directly adjoining the separation trench, Fig. 34 the view of Fig. 20 limited to the area of Fig. 33 for the variant with a contact opening directly adjoining the dividing trench laterally, Fig. 35 the view of Fig. 33 in the manufacturing stage after forming the electrical insulation layer structure, Fig. 36 the view of Fig. 34 in the manufacturing stage of Fig. 35, Fig. 37 the view of Fig. 35 in the manufacturing stage after forming the through-contact openings, Fig. 38 the view of Fig. 36 in the manufacturing stage of Fig. 37, Fig. 39 the view of Fig. 37 in the manufacturing stage after forming the electrical connection structure, Fig. 40 the view of Fig. 38 in the manufacturing stage of Fig. 39, Fig. 41 the view of Fig. 36 for a variant with formation of the electrical insulation layer structure with a larger, constant lateral width, Fig. 42 the view of Fig. 41 in the manufacturing stage of Fig. 38 and Fig. 43 the view of Fig. 42 in the manufacturing stage of Fig. 40.

[0046] The thin-film solar module shown in the figures in different implementations according to the invention can have any structure familiar to those skilled in the art, unless this is discussed in more detail below. That is to say, the figures and the following explanations deal primarily with the essential features, functions and properties of the invention, or with information helpful for understanding the invention, while, depending on requirements and application, the thin-film solar module can have further elements or components of a conventional type, the implementation of which is known to those skilled in the art, and therefore requires no further explanation here.

[0047] As can be seen from the partial and schematic representations in the figures, the thin-film solar module comprises a solar cell array 1 with a plurality of solar cells 2 having a layered structure that includes a back contact layer 3, a front contact layer 4, and an absorber layer 5 between the back contact layer 3 and the front contact layer 4, as is typical for conventional thin-film solar cells. Depending on the application, the layered structure may include one or more additional conventional layers, such as buffer layers, barrier layers, protective layers, etc., which are not relevant here and are therefore not shown. Furthermore, the thin-film solar module includes an electrical interconnection structure for the series connection of adjacent solar cells, e.g., for the series connection of three cells in the... Fig. 1 and Fig. 2 and some further figures show exemplary and partially detailed solar cells 21, 22, 23, wherein the connection structure contacts the back contact layer 3 of a first solar cell 21 on a side 3a facing the absorber layer and the front contact layer 4 of a solar cell connected in a series direction R S The second solar cell 22, adjacent to the first solar cell, is contacted on a side 4b facing away from the absorber layer, as also shown for example in the Fig. 1 and Fig. This can be seen in Figures 2 and some other figures. The front contact layer 4, with its side 4b facing the absorber layer, contacts the absorber layer 5 or is at least oriented towards it.

[0048] The back contact layer 3 can be formed, for example, as in the embodiments shown, in a conventional manner on a module substrate 16, i.e., a module substrate body, wherein its side 3b facing away from the absorber layer contacts the module substrate 16, i.e., is in contact with it, or at least faces it. The module substrate 16 can, for example, be a glass substrate or another transparent or non-transparent plate- or disk-shaped support body, such as is commonly used for thin-film solar modules.

[0049] The solar cells, arranged side by side and electrically connected in series, such as the first and second solar cells 21, 22, are separated from each other by a respective separating trench 6, which extends continuously through the front contact layer 4, the absorber layer 5 and the back contact layer 3, as for example from Fig. Figure 2 and similar figures show that the dividing trench 6 extends over a total length that can typically range from 1 cm to 6 m.

[0050] The first solar cell 21 has at least one contact opening 7 that extends through the front contact layer 4 and the absorber layer 5 to the back contact layer 3, as also shown, for example, in Fig. 2. In corresponding versions, the contact opening 7 is arranged at a lateral distance from the separating trench 6, as in the examples of the Fig. 1 to 32, in alternative versions it borders directly on the dividing trench 6, as in the examples of the Fig. 33 to 43, overlapping laterally with this or directly adjoining it.

[0051] The electrical connection structure includes at least one electrical connection element 8 extending across the separation trench 6, which on the one hand contacts the front contact layer 4 of the second solar cell 22 on the side 4b facing away from the absorber layer, and on the other hand extends into the contact opening 7 of the first solar cell 21 and there contacts the back contact layer 3 of the first solar cell 21 on the side 3a facing the absorber layer. The electrical connection element 8 is electrically insulated in the contact opening 7 from the absorber layer 5 and the front contact layer 4 of the first solar cell 21.In realizations in which the contact opening 7 is arranged at a lateral distance to the separating trench 6, the electrical connecting element 8 extends in a region 15 between the contact opening 7 and the separating trench 6 above the front contact layer 4 of the first solar cell 21, and is also electrically insulated from the front contact layer 4 of the first solar cell 21 in this region.

[0052] In corresponding embodiments, a maximum dimension K L a contact surface of the electrical connecting element 8 with the back contact layer 3 of a respective solar cell, e.g. the first solar cell 21, in the contact opening 7 smaller than twenty times a lateral distance K A the contact opening 7 to a contact point of the electrical connecting element 8 with the front contact layer 4 of a serially connected, adjacent solar cell, e.g. the second solar cell 22. The aforementioned maximum contact area dimension K Land the aforementioned lateral distance K A are representative in the Fig. 4 and Fig. 25 explicitly stated. This dimensioning reflects the fact that the electrical connection structure in this case is a point-like rather than a line-like electrical contact. This means that the electrical series connection of the solar cells is not achieved, as in conventional connection technology, via contact lines extending across virtually the entire length of the respective solar cell perpendicular to the series connection direction, but rather via through-contacts with a more point-like configuration. Consequently, this can also be described as point interconnection, in contrast to conventional line interconnection. The point shape can be, for example, a circle, oval, or polygon. In corresponding implementations, the maximum contact area dimension K is Lless than five times or less than twice the said distance K A , and in advantageous embodiments it is at most as large as, or even smaller than, the aforementioned distance K. A e.g. less than half, one-fifth or one-seventh of the distance K A Additionally or alternatively, this maximum dimension K L the contact area of ​​the electrical connecting element 8 is smaller than one fiftieth of the total length of the separating trench 6, in particular smaller than one thousandth and preferably smaller than one twenty thousandth of the total length of the separating trench 6.

[0053] In corresponding embodiments, the electrical connecting element 8 contacts the back contact layer 3 of a respective solar cell, e.g. the first solar cell 21, in the contact opening 7 at a first contact point 9 and the front contact layer of a serially connected, adjacent solar cell, e.g. the second solar cell 22, at a second contact point 10, wherein the second contact point 10 is in a direction relative to the series connection direction R S perpendicular direction R N is arranged offset from the first contact point 9. Such implementations are found, for example, in the Fig. 5, Fig. 9 and Fig. Figure 10 shows that this offset may be advantageous for forming the electrical connection structure within an in-line manufacturing process.

[0054] In corresponding embodiments, the electrical connection structure has a plurality of electrical connection elements 8 for the electrical series connection of each pair of solar cells, e.g. the first solar cell 21 and the second solar cell 22, wherein the connection elements 8 in this case are electrically parallel in a direction R relative to the series connection direction. S non-parallel direction R A are arranged at a distance from each other. The non-parallel direction R A can be perpendicular or oblique to the series connection direction R S be oriented. All illustrated examples are of this type, with the following being representative: Fig. 1 and Fig. 15 Two such parallel-offset electrical connecting elements 81, 82 are explicitly marked. This arrangement of several electrical connecting elements 8 for the electrical series connection of each pair of solar cells can have a favorable effect on current transport and current distribution.

[0055] In corresponding embodiments, the electrical connection structure comprises a plurality of electrical connection elements 8 for the electrically serial connection of each pair of solar cells, such as the first solar cell 21 and the second solar cell 22, such that several of the electrical connection elements contact the back contact layer 3 of the first solar cell 21 in the same first contact opening 71 and contact the front contact layer 4 of the second solar cell 22 at different second contact points 101, 102. Exemplary embodiments of this type are described in the Fig. 9 and Fig. Figure 10 illustrates this; see two electrical connecting elements 8a and 8b marked accordingly.

[0056] In corresponding embodiments, the electrical connection structure has a plurality of electrical connection elements 8 for the electrically serial connection of two solar cells, such as the first and the second solar cell 21, 22, such that several of the electrical connection elements 8 contact the front contact layer 4 of the second solar cell 22 at the same second contact point 107 and contact the back contact layer 3 of the first solar cell 21 in different contact openings 71, 72, as is the case in the embodiment of the Fig. 9 with the relevant electrical connecting elements 8c and 8d.

[0057] In corresponding embodiments, the electrical connection structure has a plurality of electrical connection elements 8 for the electrically serial connection of, for example, the first and the second solar cell 21, 22, such that at least two electrical connection elements 8e, 8f are formed from a one-piece manufactured connecting piece 8g, which contacts the back contact layer 3 of the first solar cell 21 at least in a first contact opening 74 and contacts the front contact layer 4 of the second solar cell 22 at least at two different second contact points 105, 106, as is the case in the embodiment of Fig. 9 is the case.

[0058] In corresponding embodiments, the electrical connection structure has a plurality of electrical connection elements 8 for the electrical serial connection of, for example, the first or second solar cell 21, 22, such that at least two electrical connection elements 8e, 8f are formed from a one-piece manufactured connecting piece 8g, which contacts the back contact layer 3 of the first solar cell 21 at least in two different contact openings 73, 74 and contacts the front contact layer 4 of the second solar cell 22 at least at a second contact point 106, as is also the case in the embodiment of Fig. 9 is the case. Specifically, it shows Fig. 9 an implementation in which all the electrical connecting elements 8a to 8f shown are formed by the one-piece manufactured connecting piece 8g, which zigzags in the direction R relative to the series connection S perpendicular direction R Nextends back and forth across the dividing ditch 6 several times.

[0059] In corresponding embodiments, the electrical connecting element 8 contacts the front contact layer 4 of the second solar cell 22 at two or more serially successive second contact points 10a, 10b, 10c, as in the embodiments of the Fig. 3 to 5 and 11 is the case.

[0060] In corresponding embodiments, the electrical connecting element 8 contacts the front contact layer 4 of the second solar cell 22 on a front contact grid structure 11a. Exemplary embodiments of this type are shown below. Fig. 12 and Fig. 13.

[0061] In corresponding embodiments, the electrical connecting element 8 is formed in one piece with a front contact grid structure 11b of the front contact layer 4 of the second solar cell 22. Exemplary embodiments of this type are shown below. Fig. 27 to 32.

[0062] In the example of Fig. 27 the front contact grid structure is formed of straight strips, and the electrical connecting elements 8 are in the series connection direction R S and the direction perpendicular to it R N Each arranged in a two-dimensional field. The straight stripes of the front contact grid structure 11b of Fig. 27 end with a gap in the series connection direction R S before each subsequent electrical connecting element 8.

[0063] In the example of Fig. 28 the electrical connecting elements 8 are arranged in the same way, but in this case the front contact grid structure is formed by bent and extended contact strips, which with their bent end regions facing away from the electrical connecting elements 8 each extend into a region between two in the direction R N perpendicular to the series connection direction R Sextend into successive electrical connecting elements 8.

[0064] In the example of Fig. 29 are each two along the direction R N or the series direction R A Extending rows of electrical connecting elements 8 are arranged in the two-dimensional field, offset from each other by half the distance between the electrical connecting elements 8, and the front contact grid structure 11b is in this case formed by straight, elongated strips, the ends of which, facing away from the electrical connecting elements 8, are similar to the bent ends of the strips in the front contact grid structure 11b of Fig. 28 in the area between each pair in the direction R N extend into successive electrical connecting elements 8.

[0065] In the example of Fig. 30 The front contact grid structure 11b includes a fork-shaped contact grid element formed in one piece with the associated electrical connecting element 8.

[0066] In the exemplary embodiment of Fig. 31 includes the front contact grid structure 11b, each comprising a contact grid element formed in one piece with the electrical connecting element 8, which has a three-pronged spreading shape.

[0067] In the exemplary embodiment of Fig. 32 includes the front contact grid structure 11b, a contact grid element with a comb-like structure, which is formed in one piece with the series of electrical connecting elements 8 that establish the electrically serial connection of two adjacent solar cells, such as the first and the second solar cell 21, 22, and which extends in the direction R N perpendicular to the series connection direction R S Extends continuously.

[0068] In corresponding embodiments, the respective electrical connecting element comprises a bond wire element 12. Fig. Figures 1 to 14 show examples of this type.

[0069] In advantageous embodiments, the respective bond wire element 12 comprises an electrically conductive bond wire section 12a and an electrically insulating sheath 12b surrounding it, as shown in the exemplary embodiments of the Fig. 1 to 13. In corresponding implementations, the electrically insulating covering 12b, as in the examples shown, is formed by a sheathing tube 18. The sheathing tube 18 is preferably made of a transparent material.

[0070] In the embodiments shown, the sheathing tube 18 loosely surrounds the bonding wire piece 12a in a central region 18a at a radial distance and terminates at both its end regions with a constriction 18b, 18c. Alternatively, no constriction is provided, or a constriction is provided only at one of the two end regions, or a constriction is provided in the central region 18a. In a further alternative embodiment, the sheathing tube 18 surrounds the bonding wire piece 12a tightly, e.g., as a tube element shrunk onto the bonding wire piece 12a.

[0071] In corresponding versions, the sheathing tube 18 extends in the series connection direction R S laterally on both sides beyond the dividing trench 6, as is the case in the examples shown.

[0072] In corresponding embodiments, the sheathing tube 18 extends into the contact opening 7, as in the exemplary embodiments of the Fig. 1 to 7 and 9 to 13 is the case. In other words, the sheathing tube 18 extends in this case with a certain degree, in Fig. 7 explicitly illustrated length H L into contact opening 7.

[0073] In corresponding versions, the sheathing tube 18 extends to a lateral distance S A to the contact opening 7, i.e., ends with this distance S A before the contact opening 7, as in the embodiment of Fig. 8, where this lateral distance S A The contact opening 7 is preferably less than twenty times the hose wall thickness W. D1 of the sheathing hose 18 in the associated hose end area, wherein this wall thickness W D1 from one also in Fig. 8 specified wall thickness W D The lateral distance S of the sheathing tube 18 may optionally deviate in its central region 18a, and in particular may be larger. In specific implementations, this lateral distance SA The contact opening 7 is less than five times the hose wall thickness W. D1 in the associated hose end area.

[0074] In corresponding embodiments, the bond wire element 12 comprises a bond wire 12c coated with a thermoplastic material or adhesive material 19, as in the exemplary embodiment of Fig. 14 realized. The thermoplastic material or adhesive material 19 can contribute to achieving a high adhesive strength of the contacting of the bond wire element 12, here specifically the bond wire 12c, with the back contact layer 3 of one solar cell and / or with the front contact layer 4 of the other, adjacent solar cell.

[0075] Fig. Figure 14 shows, in a microscopic representation, an exemplary contact area of ​​the bond wire 12c coated with the thermoplastic material or adhesive material 19 to a surface of the front contact layer 4 at one of the second contact points 10b in the embodiment of Fig. 11. As can be seen, the initially uniform coating of thermoplastic material or adhesive material 19 is partially displaced during the bonding process at the mechanical contact points of the bonding wire 12c with the surface of the front contact layer 4, so that the bonding wire 12c makes direct, electrically conductive contact with the front contact layer 4 and the thermoplastic material or adhesive material 19 fills gaps and spaces between the bonding wire 12c and the surface of the front contact layer 4, thereby improving the adhesion strength of the bonding wire 12c to the front contact layer 4. This can be particularly advantageous when using conventional transparent, electrically conductive oxide layers for the front contact layer, since this oxide material is rather brittle and rough and not very ductile.

[0076] In advantageous embodiments, the respective electrical connecting element comprises a material deposition element 13. Exemplary embodiments of this type are described in the Fig. Illustrated in numbers 15 to 43.

[0077] In advantageous realizations, the thin-film solar module in this case, as in these examples shown, includes an electrical insulation layer structure 14 which surrounds the respective material deposition element 13 in the contact opening 7 and, if the contact opening 7 is arranged at a lateral distance to the separating trench 6, electrically separates it in the area 15 between the contact opening 7 and the separating trench 6 from the underlying front contact layer 4 of the solar cell in which the contact opening 7 is located.

[0078] The material deposition element 13 is an element made of an electrically conductive material, formed by a suitable conventional deposition process, either by full-surface deposition with subsequent structuring or by targeted deposition only in the areas where the material deposition element 13 is to be present. Any suitable conventional technique can be used for this purpose, such as printing, vapor deposition, sputtering, or dispensing.

[0079] In advantageous embodiments, the electrical insulating layer structure 14, as in the examples shown, is located not only in the respective contact opening 7 and, if applicable, in the area 15 between the contact opening 7 and the separating groove 6 above the front contact layer 4, but also in the separating groove 6 itself; that is, the separating groove 6 is filled with the electrically insulating material of the insulating layer structure 14. This electrically insulating material in the separating groove 6 thus protects the exposed areas or edges of the back contact layer 3, the absorber layer 5, and the front contact layer 4.

[0080] In the illustrated examples of the Fig. 15 to 43 are the contact openings 7, just as in the exemplary embodiments of the Fig. 1 to 14 preferably formed with a circular, optionally with another cross-section, e.g. an oval or polygonal cross-section. In contrast to the contact openings 7 in the examples of the Fig. Numbers 1 to 14 are the contact openings 7 in the examples of the Fig. 15 to 43 circumferentially filled with the material of the insulating structure 14 and in a central region with the electrically conductive material of the material deposition element 13, wherein the electrically conductive material extends as a through-contact section 13a of the material deposition element 13 in the contact opening 7 through a corresponding through-contact opening 17 in the insulating layer structure 14, as for example in the Fig. 16, Fig. 18, Fig. 25 and Fig. 39. The material deposition element 13 electrically contacts the back contact layer 3 of the respective solar cell 21, 22, 23,... at its absorber layer-facing side 3a via the through-contact section 13a.

[0081] On its upper side, the through-contact section 13a transitions into a lateral bridging section 13b of the material deposition element 13, with which the material deposition element 13 extends laterally from the area of ​​the contact opening 7 over the area 15 between the contact opening 7 and the separating trench 6 and over the separating trench 6 to the absorber layer-facing side 4b of the front contact layer 4 of the respective adjacent solar cell to be connected serially and electrically contacts the front contact layer 4 there.

[0082] The through-contact section 13a and the bridging section 13b of the respective material deposition element 13 can be formed as a single piece in the same manufacturing process or as two pieces through successive deposition processes, depending on requirements and application. In the exemplary embodiments of the Fig. 27 to 43, the respective metal deposition element 13 with its bridging section 13b is manufactured in one piece and transitions into the respective front contact grid structure 11b.

[0083] The module, and in particular its solar cell array 1, is dimensioned according to the requirements of the respective application, as is customary. This also applies in particular to the components of the electrical connection structure, especially with regard to the electrical connection elements 8. Some dimensioning details in this regard are given in the Fig. 15, Fig. 17 and Fig. 18 is marked for the version variant with the material separation elements 13.

[0084] The diameter d1 of the through-contact section 13a of the material deposition element 13 can, for example, be in the range between 5 µm and 100 µm, e.g. at approximately 20 µm, and corresponds, in the case of a circular cross-section of the contact section 13a, to the maximum dimension K mentioned above.LThe contact surface of the relevant electrical connecting element 8 with the back contact layer 3 of the associated solar cell in the contact opening 7. A dimension d2, or diameter of the contact opening 7, can be, for example, in the range of 15 µm to 500 µm, e.g., approximately 60 µm. In advantageous embodiments, the dimension d1 is in the range between 10% and 90% of the dimension d2. This ensures, on the one hand, a sufficiently high current transmission capacity of the through-contact and, on the other hand, reliable short-circuit protection to the adjacent side walls of the absorber layer 5 and the front contact layer 4. A lateral residual length d3 of the bridging section 13b of the material deposition element 13, measured from the contact opening 7, can be, for example, in the range between 25 µm and 30 mm, e.g., approximately 160 µm.The length d4 of the bridging section 13b, projecting laterally beyond the insulation layer structure 14 and along which the material deposition element 13 contacts the front contact layer 4 of the next solar cell, can vary over a wide range, depending, among other things, on whether a front contact grid structure is simultaneously integrated with the material deposition element 13. Without such a front contact grid structure, the dimension d4 can, for example, be in the range between 5 µm and 500 µm, e.g., approximately 20 µm. With such a front contact grid structure, lengths of up to 30 mm are possible for dimension d4. The area 15 between the separating groove 6 and the contact opening 7 has a width d5, which can, for example, be between 0 and 200 µm, e.g., approximately 100 µm. To a certain extent, the contact opening 7 can even overlap with the separating groove 6. The separating trench 6 has a lateral width d6, which can be between 5 µm and 250 µm, for example at approximately 20 µm.In preferred embodiments, the ratio of the lateral width d6 of the separating groove to a lateral wall thickness (d2-d1) / 2 of the electrical insulating layer structure 14 in the contact opening 7 is between 100:1 and 1:100, particularly between 10:1 and 1:10, and preferably substantially 1:1. The insulating layer structure 14 preferably projects laterally from the separating groove 6 onto the front contact layer 4 with a dimension d7, which is, for example, in the range between 0 and 100 µm, e.g., at approximately 20 µm. If the separating groove 6 is drawn with a mechanical cutter, the insulating layer structure 14 is formed such that it reliably covers any conchoidal defects or other anomalies of the layer stack at the edge of the separating groove 6. The electrical insulation layer structure 14 has a lateral dimension d8 in the series direction R in the vicinity of the contact opening 7. A, which can, for example, lie between approximately 15 µm and 1000 µm, e.g., at approximately 60 µm. The material deposition element 13 has a lateral width d9 in the direction R relative to the series connection. S non-parallel series direction R A The electrical connecting elements 8 or material deposition elements 13, which can be, for example, between 5 µm and 400 µm, e.g., at approximately 30 µm. A grid spacing d10 of the material deposition elements 13 in the series direction R A For example, it can be in the range between 100 µm and 3 mm, e.g. at approximately 500 µm.

[0085] The Fig. 15 and Fig. 16 on the one hand, and the Fig. 17 and Fig. 18 On the other hand, two embodiments are shown with different dimensions of the material deposition elements 13 and their surroundings, e.g. with different distances d5 from separation trench 6 and contact opening 7 and with different lateral widths d9 of the material deposition elements 13 relative to the lateral width d8 of the insulation layer structure 14 in the row direction R. A .

[0086] The following refers specifically to the Fig. 19 to 26 as well as on the Fig. Sections 33 to 43 discuss advantageous embodiments of the thin-film solar module according to the invention with the material deposition elements 13, particularly with regard to embodiments of the manufacturing process according to the invention that are suitable for their production. These sections relate to... Fig. 19 to 26 on a realization in which the respective contact opening 7 is arranged at a lateral distance to the separating trench 6, while the Fig. Figures 33 to 43 illustrate realizations in which the respective contact opening 7 is arranged directly adjacent to or alongside the separating trench 6 without any lateral distance, or overlapping it laterally. These illustrate Fig. 41 to 43 a variant of the one in the Fig. 33 to 40 of the module or process shown with a different deposition width of the electrical insulation structure 14.

[0087] To manufacture the thin-film solar module in question, the back contact layer 3, the absorber layer 5, and the front contact layer 4 are each successively applied to the module substrate 16 using standard layer deposition processes, covering their entire surface. This may include the application of additional layers, such as buffer and / or passivation layers, as is known to those skilled in the art and therefore requires no further explanation here. Subsequently, the separation grooves 6 are introduced into the prefabricated layer structure through the front contact layer 4, the absorber layer 5, and the back contact layer 3, and the contact openings 7 are formed through the front contact layer 4 and the absorber layer 5 to the back contact layer 3.

[0088] The creation of the separation grooves 6 on the one hand and the contact openings 7 on the other can be carried out simultaneously in a single manufacturing process or sequentially, as desired – i.e., first the separation grooves 6 and then the contact openings 7, or vice versa. The separation grooves 6 structure the array 1 into the individual solar cells 21, 22, 23, ... and can be created, for example, mechanically, by laser beam, or by an etching process. Multi-step processes of a conventional nature can also be used. For example, the separation grooves 6 can be formed by mechanically removing all layers except the back contact layer 3 in a first step, e.g., by a stylus process. This process is known from the conventional monolithic series interconnection of CIGS thin-film solar cells and is usually referred to there as the "P3" structuring step. The remaining back contact layer 3 is then, for example,The substrate is separated by a laser process. The laser beam can act on the back contact layer 3 from the layer side and / or, in the case of a sufficiently transparent substrate, also through the substrate, causing its targeted detachment. Depending on the widths and relative positions of the cutting lines of the two sub-steps, the respective separation trench 6 is formed with continuously aligned flanks or with stepped flanks. In particular, the width of the separation trenches 6 in the area of ​​the back contact layer 3 can be smaller than in the area of ​​the subsequent absorber and front contact layers 5, 4, deviating from the shape shown in the figures. Alternatively, methods known per se can be used in which both sub-steps are carried out by laser processes for which different, adapted laser parameters are set, especially with regard to the laser wavelength.Alternatively, conventional laser processes can be used, in which the layer stack, including the back-contact layer, is removed in a single laser pass to form the separation trench. With all these processes, the layer flanks in the separation trench area can deviate from the idealized rectangular representation shown, e.g., by forming conchoidal outcrops, melting, uplifts, cracks perpendicular to the laser direction of movement, inclined flanks, etc., as is well known from the technical literature, to which reference can be made.

[0089] The contact openings 7 are located in the corresponding area of ​​the back contact layer 3 on their absorber layer-facing side 3a and can be created, for example, by means of a laser beam or an etching process. Fig. 19 and Fig. Figure 20 shows array 1 at this stage of the process for the case of the contact opening 7 spaced laterally from the separation trench 6, which Fig. 33 and Fig. Figure 34 shows array 1 at this stage of the process for the case of the contact opening 7 laterally adjacent to the separation trench 6. In the latter case, there is no lateral separation between the contact opening 7 and the separation trench 6 by material of the absorber layer 5 and the front contact layer 4, as shown from Fig. 33 in contrast to Fig. 19 is evident. Rather, the contact opening 7 for these two layers 4, 5 forms a lateral bulge of the separation trench 6, whereby in the depth direction the contact opening 7 extends only as far as the back contact layer 3, while the separation trench 6 passes through it.

[0090] The Fig. 21 and Fig. 22 or the Fig. 35 and Fig. Figure 36 illustrates the subsequent formation of the electrical insulation layer structure 14 with complete filling of both the separation grooves 6 and the contact openings 7. Depending on the requirements and application, this can be achieved by applying the insulation layer material over the entire surface and then structuring it, or by directly applying this material in its structured form, in the latter case, for example, by a printing or spraying process or a dispensing process of a type known per se. In the process variants of the Fig. From 19 to 40, the electrical insulation layer structure 14 is formed outside the area of ​​the contact opening 7 with a lateral width that extends only comparatively slightly beyond the separating groove 6 on both sides, forming a lateral bulge in the area of ​​the contact opening 7, which fills the contact opening, as can be seen in particular from the top views of the Fig. 22 and Fig. 36 is evident. In the procedural variant of the Fig. 41 to 43, the electrical insulation layer structure 14 is formed with a uniform, larger width along its entire length, sufficient to fill the contact opening in the area of ​​the contact opening, as shown in particular by Fig. 41 compared to Fig. 36. This formation of the electrical insulation layer structure 14 with a consistently uniform lateral width can simplify this manufacturing step and thus the manufacturing of the module as a whole in corresponding applications.

[0091] In the procedural stage of the Fig. 23 and Fig. 24 or the Fig. 37 and Fig. 38 or the Fig. 42 The through-holes 17 are then introduced into the insulating layer structure 14 in the area of ​​the respective contact opening 7 using a common technique for this purpose, such that each contact opening 7 is completely surrounded on its circumference by the insulating layer structure 14 and only the back contact layer 3 is exposed on its absorber layer-facing side 3a in the desired area.

[0092] In an alternative process variant, the contact openings 17 are formed simultaneously with the formation of the electrical insulating layer structure 14. For this purpose, the insulating layer material is not applied to the respective contact opening 7 completely or filling its entire cross-section, but rather in a ring shape, so that a cavity remains inside this ring of material, forming the corresponding contact opening 17. This can be achieved, for example, using a suitable inkjet printing technique or a dispenser technique. In the case of the dispenser technique, a conventional dispenser cannula can be guided in a ring-forming manner, or a ring of dots or circular segments can be produced using a special dispenser setup, or a continuous ring can be produced using a coaxial dispenser nozzle.If necessary, this dispensing process is supported by the supply of blown air or another blowing medium as in corresponding blown film processes, so that a void forming the through-contact opening 17 remains in a central area of ​​the contact opening 7.

[0093] Subsequently, in the procedural stage of the Fig. 25 and Fig. 26 or the Fig. 39 and Fig. 40 or the Fig. 43 The material deposition elements 13 are formed with their through-contact section 13a, which fills the respective through-contact opening 17, and their bridging section 13b, wherein these two sections 13a, 13b are preferably formed in the same manufacturing process, but can alternatively also be formed by two successive material deposition processes. A manufacturing process known per se for producing such an electrically conductive structure can again be used to form the material deposition elements 13, e.g., in the form of full-surface deposition and subsequent structuring by etching or the like, or alternatively by means of a screen printing, digital printing, or dispensing process. Preferably, the material deposition elements 13 extend over the electrical insulation layer structure 14 at a lateral distance from an edge of the electrical insulation layer structure 14, i.e.,They do not extend quite to the edge of the electrical insulation layer structure 14, but remain somewhat behind it, as in the . Fig. 25 and Fig. 26 or 39 and Fig. Figure 40 shows the right edge. This prevents potential short circuits caused by the material of the material deposition elements 13 extending laterally beyond the edge of the electrical insulation layer structure 14. In preferred embodiments, the material deposition elements 13 cover the electrical insulation layer structure 14 to a proportion of between 10% and 90% with respect to a linear dimension, in particular its lateral extent.

[0094] If required, the front contact grid structure 11b can be formed simultaneously with the formation of the material deposition elements 13, if design variants with an integrated front contact grid structure 11b are produced, such as the design variants of the Fig. 27 to 32.

[0095] It should be mentioned at this point that, as an alternative to the procedural steps according to the Fig. 21 to 26 and 35 to 43, which refer to the design variant with the material separation elements 13 as electrical connecting elements 8, following the one relating to the Fig. 19 and Fig. The 20 described process steps allow a bond contact process or bond wiring process to be carried out in order to realize one of the alternative module variants with the bond wire elements 12 as electrical connecting elements 8, as described in the Fig. Numbers 1 to 14 are shown.

[0096] As the illustrated embodiments explained above clearly demonstrate, the invention advantageously provides a thin-film solar module in which very little dead area is lost for the series connection of the solar cells. Bond wire elements or material deposition elements can be used as electrical connection elements. Furthermore, the invention provides an associated manufacturing process with which such thin-film solar modules can be produced with relatively little effort.

Claims

[1] Thin-film solar module with - a solar cell array (1) comprising a plurality of solar cells (2) with a layer structure comprising a back contact layer (3), a front contact layer (4) and an absorber layer (5) between the back contact layer and the front contact layer, and - an electrical connection structure for electrically connecting solar cells (21, 22, ...) arranged next to one another in series, wherein the connection structure contacts the rear contact layer of a first solar cell (21) on a side (3a) facing the absorber layer and the front contact layer of a solar cell (21) arranged in a series connection direction (R S ) contacted with the second solar cell (22) adjacent to the first solar cell on a side (4b) facing away from the absorber layer, wherein - a separation trench (6) extends continuously through the front contact layer (4), the absorber layer (5) and the rear contact layer (3) and separates the first and second solar cells (21, 22) from each other, - the first solar cell (21) has at least one contact opening (7) which extends through the front contact layer (4) and the absorber layer (5) to the rear contact layer (3), and - the electrical connection structure has at least one electrical connection element (8) extending across the separation trench, which on the one hand contacts the front contact layer (4) of the second solar cell (22) on the side (4b) facing away from the absorber layer and on the other hand extends into the contact opening (7) of the first solar cell and there contacts the rear contact layer (3) of the first solar cell on the side (3a) facing the absorber layer, wherein the electrical connection element is electrically insulated in the contact opening from the absorber layer and the front contact layer of the first solar cell and, if the contact opening is arranged at a lateral distance from the separation trench, extends in a region (15) between the contact opening and the separation trench above the front contact layer of the first solar cell, electrically insulated from the latter, and wherein - the electrical connection element comprises a bonding wire element (12) which comprises an electrically conductive bonding wire piece (12a) and an electrically insulating sheath (12b) surrounding it, or which comprises a bonding wire (12c) coated with a thermoplastic material or adhesive material (19), or - an electrical insulation layer structure (14) is provided which surrounds a material deposition element in the contact opening on the circumference and is additionally located in the separation trench and which, when the contact opening is arranged at a lateral distance from the separation trench, electrically separates the material deposition element in the region between the contact opening and the separation trench from the underlying front contact layer of the first solar cell. [2] Thin-film solar module with - a solar cell array (1) comprising a plurality of solar cells (2) with a layer structure comprising a back contact layer (3), a front contact layer (4) and an absorber layer (5) between the back contact layer and the front contact layer, and - an electrical connection structure for electrically connecting solar cells (21, 22, ...) arranged next to one another in series, wherein the connection structure contacts the rear contact layer of a first solar cell (21) on a side (3a) facing the absorber layer and the front contact layer of a solar cell (21) arranged in a series connection direction (R S ) contacted with the second solar cell (22) adjacent to the first solar cell on a side (4b) facing away from the absorber layer, wherein - a separation trench (6) extends continuously through the front contact layer (4), the absorber layer (5) and the rear contact layer (3) and separates the first and second solar cells (21, 22) from each other, - the first solar cell (21) has at least one contact opening (7) which extends through the front contact layer (4) and the absorber layer (5) to the rear contact layer (3), - the electrical connection structure has at least one electrical connection element (8) extending across the separation trench, which on the one hand contacts the front contact layer (4) of the second solar cell (22) on the side (4b) facing away from the absorber layer and on the other hand extends into the contact opening (7) of the first solar cell and there contacts the rear contact layer (3) of the first solar cell on the side (3a) facing the absorber layer, wherein the electrical connection element is electrically insulated in the contact opening from the absorber layer and the front contact layer of the first solar cell and, if the contact opening is arranged at a lateral distance from the separation trench, extends above the front contact layer of the first solar cell in a region (15) between the contact opening and the separation trench, electrically insulated from the front contact layer of the first solar cell, and - the electrical connection structure comprises a plurality of electrical connection elements (8) for electrically connecting the first and second solar cells in series, wherein - several (8a, 8b) of the electrical connecting elements contact the rear contact layer of the first solar cell in a same first contact opening (71) and contact the front contact layer of the second solar cell at different second contact points (101, 102) and / or - several (8c, 8d) of the electrical connecting elements contact the front contact layer of the second solar cell at a same second contact point (107) and contact the rear contact layer of the first solar cell in different contact openings (71, 72) and / or - at least two (8e, 8f) of the electrical connecting elements are formed from a one-piece connecting piece (8g) which contacts the rear contact layer of the first solar cell at least in a first contact opening (74) and contacts the front contact layer of the second solar cell at least at two different second contact points (105, 106) and / or contacts the rear contact layer of the first solar cell at least in two different contact openings (73, 74) and contacts the front contact layer of the second solar cell at least at a second contact point (106). [3] Thin-film solar module according to claim 1 or 2, further characterized by that a maximum dimension (K L ) of a contact area of ​​the electrical connection element with the back contact layer of the first solar cell in the contact opening is smaller than twenty times a lateral distance (K A) of the contact opening to a contact point of the electrical connection element with the front contact layer of the second solar cell and / or is smaller than one fiftieth of a total length of the separation trench, in particular smaller than one thousandth and more preferably smaller than one twenty thousandth of the total length of the separation trench. [4] Thin-film solar module according to one of claims 1 to 3, further characterized by that the electrical connecting element contacts the back contact layer of the first solar cell in the contact opening at a first contact point (9) and contacts the front contact layer of the second solar cell at a second contact point (10) which is perpendicular to the series connection direction (R N ) is offset from the first contact point. [5] Thin-film solar module according to one of claims 1 to 4, further characterized bythat the electrical connection structure comprises a plurality of electrical connection elements (81, 82) for electrically connecting the first and second solar cells in series, which are electrically connected in parallel in a direction (R A ) are arranged at a distance from each other. [6] Thin-film solar module according to one of claims 1 to 5, further characterized by , that - the electrical connecting element contacts the front contact layer of the second solar cell at two or more serially successive second contact points (10a, 10b, 10c) and / or - the electrical connection element contacts the front contact layer of the second solar cell on a front contact grid structure (11a) and / or - the electrical connection element is formed in one piece with a front contact grid structure (11b) of the front contact layer of the second solar cell. [7] Thin-film solar module according to claim 2, further characterized by that the electrical connection element comprises a bonding wire element (12) or a material deposition element (13). [8] Thin-film solar module according to claim 7, further characterized by that the bonding wire element comprises an electrically conductive bonding wire piece (12a) and an electrically insulating sheath (12b) surrounding it. [9] Thin-film solar module according to claim 1 or 8, further characterized by , that - the electrically insulating sheath is formed by a sheathing tube (18), - wherein the sheathing tube is made of a transparent material and / or - wherein the sheathing tube loosely surrounds the bonding wire piece at a radial distance in a central region (18a) and terminates at its two end regions with a constriction (18b, 18c) and / or - whereby the sheathing tube extends laterally beyond the separation trench on both sides in the series connection direction and / or - whereby the sheathing tube extends into the contact opening or up to a lateral distance (S A ) to the contact opening of less than twenty times its hose wall thickness (W D1 ) in the associated hose end area, in particular less than five times its hose wall thickness in the associated hose end area. [10] Thin-film solar module according to claim 7 or 8, further characterized by that the bonding wire element comprises a bonding wire (12c) coated with a thermoplastic material or adhesive material (16). [11] Thin-film solar module according to claim 7, further characterized byan electrical insulation layer structure (14) which surrounds the material deposition element in the contact opening on the circumference and, when the contact opening is arranged at a lateral distance from the separation trench, electrically separates it in the region between the contact opening and the separation trench from the underlying front contact layer of the first solar cell. [12] Thin-film solar module according to claim 11, further characterized by that the electrical insulation layer structure (14) is additionally located in the separation trench. [13] Thin-film solar module according to one of claims 1 to 12, further characterized by , that - a current-carrying cross-section of the electrical connection element is essentially constant over its longitudinal extent from the contact point with the rear contact layer to the contact point with the front contact layer of the adjacent solar cell or varies by a maximum factor of one hundred, more preferably a maximum factor of ten, and / or - a lateral dimension (d1) of the electrical connection element in the contact opening lies in the range between 10% and 90% of a lateral dimension (d2) of the contact opening and / or - the material deposition element extends over the electrical insulation layer structure at a lateral distance from an edge of the electrical insulation layer structure and covers the electrical insulation layer structure to a proportion of between 10% and 90% with respect to a given extension direction and / or - the ratio of a lateral width (d6) of the separation trench to a lateral wall thickness ((d2-d1) / 2) of the electrical insulation layer structure in the contact opening is between 100:1 and 1:100, in particular between 10:1 and 1:10 and more preferably substantially 1:

1. [14] A method for producing a thin-film solar module according to any one of claims 1 to 13, comprising the following steps: - forming the layer structure with the back contact layer (3), the absorber layer (5) and the front contact layer (4) on a module base (16), - forming the separation trench (6) through the front contact layer, the absorber layer and the back contact layer for separating the layer structure at least into the first and the second solar cell (21, 22), - forming the at least one contact opening (7) in the first solar cell (21) through the front contact layer and the absorber layer to the rear contact layer, - forming the electrical connection structure with the at least one electrical connection element (8) which extends between the front contact layer of the second solar cell (22) and the rear contact layer of the first solar cell across the separation trench and in the contact opening, and - Completing the thin-film solar module according to one of claims 1 to 13. [15] Method according to claim 14 for producing a thin-film solar module according to one of claims 1, 11 and 12, wherein after forming the at least one contact opening and before forming the electrical connection structure, the electrical insulation layer structure (14) is formed with partial or complete filling of both the separation trench and the contact opening and a via opening (17) is provided through the contact opening.

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