Solar module with three-terminal tandem solar cells

Abstract

The invention relates to a solar module (19) and a solar installation (37) made of multiple solar modules. The solar module has multiple 3TT solar cells (11), which are wired together in order to form at least one string (21), and at least two current input connections (27) at a current input of the solar module and / or at least two current output connections (29) at a current output of the solar module. Each 3TT solar cell has a stack comprising a top cell (3) and a bottom cell (5) arranged under the top cell, and each 3TT solar cell has a top contact (13), a bottom contact (15), and a central tap contact (17) as terminal contacts. A first current input connection (27') of the current input connections (27) is at least connected to one of the terminal contacts of a first 3TT solar cell (11') lying closest to the current input, and a second current input connection (27") of the current input connections (27) is at least connected to one of the terminal contacts of a second 3TT solar cell adjoining the first 3TT solar cell, and / or a first current output connection (29') of the current output connections is at least connected to one of the terminal contacts of a final 3TT solar cell (11") lying closest to the current output, and a second current output connection (29") of the current output connections is at least connected to one of the terminal contacts of a penultimate 3TT solar cell adjoining the final 3TT solar cell. The aforementioned wiring allows, among others, a substantial prevention of string end losses as well as an advantageous integration of bypass diodes (33, 35).

Description

SOLAR MODULE WITH 3-TERMINAL TANDEM SOLAR CELLS FIELD OF THE INVENTION The present invention relates to a solar module with tandem solar cells. TECHNICAL BACKGROUND Solar modules are used to convert light, particularly that radiated by the sun, into electrical energy. Such solar modules are also referred to as photovoltaic modules or PV modules. A solar module comprises a plurality of solar cells connected in series and / or parallel. The solar module also typically has a power input connection and a power output connection to connect the solar module with other solar modules in series and / or parallel to form a solar system and ultimately to supply the electrical energy generated in the solar module to an external circuit with connected loads. Traditionally, solar modules typically utilized solar cells in which charge carrier pairs generated by the absorption of incident light are separated at a single potential difference, for example, created by a pn junction. The performance or efficiency of the solar cells depends, among other things, on the potential difference and thus on the (semiconductor) material used to generate the potential difference. The efficiency of the solar cells is limited, among other things, by the fact that, depending on the band gap of the semiconductor material used, a low-energy portion of the incident light cannot be absorbed, and a high-energy portion can only be converted into electrical energy with considerable energy losses. In order to increase the efficiency of solar cells, solar cells have been developed in which two or more partial solar cells are stacked on top of one another. Such solar cells are called tandem solar cells or sometimes also multi-junction solar cells or stacked solar cells. The two partial solar cells differ in their materials and thus in their band gaps. A partial solar cell facing the incident light, also called the top cell, typically has a larger band gap and is thus designed to absorb and convert a high-energy portion of the incident light with relatively little energy loss. Another partial solar cell arranged below, also called the bottom cell, has a smaller band gap and is thus designed to absorb and convert a low-energy portion of the incident light with relatively little loss. Tandem solar cells are preferably monolithic. This means that a tandem solar cell is designed as a single component in which all components, such as various semiconductor layers and contacts, are firmly connected to one another. For this purpose, for example, several layers can be deposited on top of one another over the entire surface and / or in partial areas. The tandem solar cell has at least two terminal contacts, but in some implementations, as explained below, three, four, or more. A terminal contact is understood to be an electrical contact on the tandem solar cell that is accessible from the outside and via which the solar cell or its sub-solar cells can be electrically connected to other solar cells or their sub-solar cells. Various interconnection configurations are known for tandem solar cells. So-called 2-terminal tandem solar cells, also known as 2TT solar cells, have only two terminal contacts, with a so-called top contact on the front and a so-called bottom contact on the back of the tandem solar cell. Such 2TT solar cells are easy to connect in a solar module, i.e. essentially like conventional non-tandem solar cells. However, the fact that the total current flowing through the 2TT solar cell must be the same for both solar cells means that this current is limited by the weaker of the two solar cells. Accordingly, losses due to current mismatch regularly occur. The reason for this can be, on the one hand, that the band gaps of the two solar cells are due to The technological conditions are not optimally selected, and one solar cell generates a higher current than the other, with the lower current of the weaker solar cell then limiting the total current of the tandem solar cell. On the other hand, even with an optimal choice of band gaps, a change in the incident light spectrum can lead to current mismatch effects. Losses due to current mismatches can be largely avoided if the individual solar cells of the tandem solar cells can be contacted and interconnected separately. For this purpose, a tandem solar cell can have four terminal contacts, i.e., be designed as a so-called 4TT solar cell. Each individual solar cell has its own two terminal contacts and can therefore be operated at its optimal operating point independently of the other solar cells. However, this requires all solar cells to be processed, contacted, and interconnected separately, which requires additional effort and can result in increased optical shading. As a kind of middle ground between 2TT solar cells and 4TT solar cells, tandem solar cells with three terminal contacts were developed, which are accordingly referred to as 3TT solar cells. In addition to a top contact and a bottom contact, 3TT solar cells have an additional terminal contact, known as a center tap. The center tap contacts both the top cell as a second terminal contact in addition to the top contact, and the bottom cell as a second terminal contact in addition to the bottom contact. This allows 3TT solar cells to be used for electrical interconnection within a solar module, significantly reducing losses due to current mismatches.On the other hand, interconnection of the 3TT solar cells within the module may be less complex than with 4TT solar cells and / or losses due to optical shading due to a large number of terminal contacts may be lower than with 4TT solar cells. 3TT solar cells and solar modules constructed with them have long been the subject of both theoretical and experimental investigations. Considerations and findings regarding their internal structure, as well as their arrangement and interconnection in solar modules, are presented, among others, in the following documents, some of which are referenced in the following text: [1] Sakai, S. and Umeno, M., “Theoretical analysis of new wavelength-division solar cells,” Journal of Applied Physics, vol. 51, no. 9, pp. 5018-5024, 1980. [2] Gee, JM, “A comparison of different module configurations for multi-band-gap solar cells,” Solar Cells, vol. 24, no. 1-2, pp. 147-155, 1988. [3] Jimeno, J. C., Gutierrez, R., Fano, V., Habib, A., del Canizo, C., Rasool, M. A., and Otaegi, A., “A 3 terminal parallel connected silicon tandem solar cell,” Energy Procedia, vol. 92, pp. 644-651, 2016. [4] Nagashima, T., Okumura, K., Murata, K., and Kimura, Y., “Three-terminal tandem solar cells with a back-contact type bottom cell,” 2000. In Proceedings of the 28th IEEE PVSC, 1193-96. http: / / ieeexplore.ieee. org / servlet / opac?punumber=7320. [5] McMahon, William; Schulte-Huxel, Henning; Buencuerpo, Jeronimo; Geisz, John; Young, Michelle; Klein, Talysa et al. (2021): Homogenous Voltage-Matched Strings Using Three- Terminal Tandem Solar Cells: Fundamentals and End Losses. In: IEEE J. Photovoltaics 11 (4), S. 1078-1086. DOI: 10.1109 / JPHOTOV.2021.3068325. [6] Jimeno Cuesta, J., Luque Lopez, A., Recart Baranano, F., Lago Aurrekoetxea, R, Gutierrez Serrano, R, Varner, K., Ikaran Salegi, C. et al. “Photovoltaic device and photovoltaic panel,” WO / 2011 / 045462, filed Oct. 14, 2010, issued Apr. 21, 2011. [7] Borden, P. G. “Three-terminal solar cell circuit,” US4513168 A, filed 19.04.1984, issued 23.04.1985. [8] H. Uzu, G. Koizumi, “SOLAR CELL MODULE”, WO / 2020 / 196288, 19.03.2020, issued 01.10.2020. [9] E. L. Warren et al., “A taxonomy for three-terminal tandem solar cells,” ACS Energy Lett., vol. 5, no. 4, pp. 1233-1242, Apr. 2020

[0010] M. Zehender et al., “Module interconnection for the three-terminal heterojunction bipolar transistor solar cell”, AIP Conference Proceedings 2012, 040013 (2018); https: / / doi.org / 10.1063 / L5053521, Published Online: 13 September 2018

[0011] H. Schulte-Huxel et al., “String-Level Modeling of Two, Three, and Four Terminal Si-Based Tandem Modules,” IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 8, NO. 5, SEPTEMBER 2018, p. 1370 - 1375

[0012] R. Witteck et al., “Partial shading of one solar cell in a photovoltaic module with 3-terminal cell interconnection,” Solar Energy Materials & Solar Cells 219 (2021) 110811 It has been observed that efficiencies or power yields of solar modules constructed with 3TT solar cells can be suboptimal, i.e. in particular, they can be lower than would be expected based on the efficiencies of the individual solar cells and the number of solar cells in a solar module. SUMMARY OF THE INVENTION AND EMBODIMENTS There may therefore be a need for solar modules that enable higher efficiencies or power yields. In particular, there may be a need for solar modules based on 3TT solar cells, where a high efficiency of the individual solar cells, due to a suitably selected configuration of the solar cells within the solar module, leads to a high efficiency of the entire solar module. Furthermore, there may be a need for a highly efficient solar system using such solar modules. The aforementioned needs can be at least partially met by the subject matter of one of the independent claims of the present application. Advantageous embodiments are specified in the dependent claims as well as the following description and figures. According to a first aspect of the present invention, a solar module is described which comprises a plurality of 3TT solar cells and at least two current input terminals at a current input of the module and / or at least two current output terminals at a current output of the module. The 3TT solar cells are interconnected to form at least one string. Each 3TT solar cell comprises a stack with a top cell and a bottom cell arranged beneath it, wherein the top cell and the bottom cell differ from one another with respect to the electrical voltage generated upon exposure to light.Each 3TT solar cell has three terminal contacts: a top contact that electrically contacts a side of the top cell facing away from the bottom cell, a bottom contact that electrically contacts a side of the bottom cell facing away from the top cell, and a center tap contact that electrically contacts the 3TT solar cell at an interface between the top cell and the bottom cell. A first of the current input terminals is connected to at least one of the terminal contacts of a first of the 3TT solar cells closest to the current input, and a second of the current input terminals is connected to at least one of the terminal contacts of a second of the 3TT solar cells adjacent to the first 3TT solar cell.Furthermore, a first of the current output terminals is connected to at least one of the terminal contacts of a last of the 3TT solar cells closest to the current output, and a second of the current output terminals is connected to at least one of the terminal contacts of a second-to-last of the 3TT solar cells adjacent to the last 3TT solar cell. According to a second aspect of the present invention, a solar system is described which has a plurality of solar modules according to an embodiment of the first aspect of the invention, wherein in adjacent solar modules each of the current output terminals of one of the solar modules is electrically connected to an associated current input terminal of the adjacent one of the solar modules. By way of introduction, a basic idea for embodiments of the invention described herein will be briefly explained, whereby this explanation is to be interpreted as merely a rough summary and not as limiting the invention:The present invention describes, in particular, a solar module in which, due to a special type of arrangement and interconnection of the 3TT solar cells accommodated therein, losses, in particular so-called string-end losses, such as those that occur in conventional solar modules in which the 3TT solar cells are arranged and interconnected in a conventional manner, can be largely avoided. As explained in more detail below, a key feature of the solar module presented here can be seen in the fact that the solar module does not have just a single power input terminal and a single power output terminal, as is usually the case with conventional solar modules, but rather has two or more such power input terminals and power output terminals, and these terminals are interconnected in a specific way with the 3TT solar cells within the solar module.Due to the special type of wiring and the large number of current input and output connections, string end losses caused by partial solar cells that do not contribute to the efficiency of the module or do not contribute to an optimal extent due to the wiring, are no longer caused in each connected solar cell string, i.e. at least once in each solar module. Instead, a large number of solar modules can be interconnected in such a way that corresponding end losses are only caused once in the entire large number of solar modules and thus have a significantly smaller reducing influence on the overall efficiency of a solar system. In addition, a design of a solar module with 3TT solar cells is described in which a suitable wiring of bypass diodes ensures the reliable operation of the solar module and at the same time enables the aforementioned end losses to be avoided. Possible designs and advantages of embodiments of the solar module and a method for its production are described in more detail below: A solar module, as described here, comprises a plurality of solar cells in the form of 3TT solar cells. For example, the solar module typically comprises more than ten solar cells, usually more than 50 solar cells, but usually fewer than 300 solar cells, usually fewer than 150 solar cells. Each individual solar cell is a flat diode, with an area typically between 10 cm 2 and 1000 cm 2 , usually between 100 cm 2 and 500 cm 2The thickness of a solar cell typically ranges from 10 pm to 1000 pm, usually between 50 pm and 400 pm. At least part of the solar cell can be formed on a crystalline, i.e., monocrystalline, multicrystalline, or polycrystalline, semiconductor substrate, such as a silicon wafer. Alternatively or additionally, part of the solar cell can be formed with amorphous semiconductor material, for example, in the form of one or more thin films. The solar cells are connected to form one or more strings. The entire solar cells or the partial solar cells forming these solar cells can be connected in series and / or parallel to one another. A string is understood to be the smallest unit made up of a plurality of interconnected solar cells, whereby the entire solar module can comprise several such strings connected in series and / or parallel. The number of solar cells combined in a string can depend on various influencing factors. In particular, this number is typically chosen such that an electrical voltage generated by the string when illuminated does not exceed a reverse voltage withstand value of each individual solar cell in the string. Such strings typically comprise between three and 50 solar cells connected in series, most often between six and 30 solar cells connected in series. The 3TT solar cells installed in the solar module consist of a first solar cell and a second solar cell. The first solar cell is located on the side of the solar cell facing the incident light, which is considered the upper side, and is therefore referred to as the top cell. The second solar cell is located below the first solar cell and is therefore referred to as the bottom cell. Each of the solar cells can, in turn, be connected via a single pn junction or, in the case of Application of special cell concepts with several pn junctions, which are preferably arranged one behind the other along the direction of light incidence. The top cell and the bottom cell differ in terms of the semiconductor materials they comprise. For example, the semiconductor material of the top cell typically has a larger energy band gap than that of the bottom cell, whereby the two band gaps can differ from each other by more than 20%, preferably more than 40%, or even more than 80%. Due to the different band gaps, different electrical voltages arise in the two partial solar cells when illuminated at a potential difference formed therein by suitable local doping (for example, due to a respective pn junction). In other words, the open-circuit voltages (sometimes also referred to as open-terminal voltages Voc) of the top cell and the bottom cell differ considerably.For example, the Voc of the top cell may be 30% or more, 50% or more, or even 100% or more greater than that of the bottom cell. Each 3TT solar cell comprises exactly three terminal contacts, through which it is interconnected with other 3TT solar cells. A terminal contact is generally formed by an electrically conductive layer, such as a metal layer, attached to or integrated into the solar cell. A terminal contact can be formed by a single layer, but it can also be composed of multiple sub-regions or sub-layers. The three terminal contacts can be designated according to a convention introduced by Warren et al. (see document [9] in the list of documents cited in the introduction to the description). A first contact is typically arranged on a front surface of the solar cell facing the incident light and electrically contacts the side of the top cell facing away from the bottom cell (whereby "electrically contacting" is generally understood to mean direct electrical contact, i.e., without the interposition of other electrical components, i.e., in particular, an ohmic contact). The first contact is referred to herein as the top contact, but can also be referred to as a T-contact (with "T" for top) according to the Warren convention.A second contact is typically arranged on a back surface of the solar cell facing away from the incident light and electrically contacts that side of the bottom cell. which faces away from the top cell. The second contact is referred to herein as the bottom contact, but can also be referred to as an R contact (with "R" standing for root) according to the Warren convention. A third contact can, for example, be arranged in a plane between the top cell and the bottom cell. As explained in more detail below, the third contact can also be spatially arranged on the back surface of the solar cell, whereby the bottom cell and the third contact can be configured such that an electrical current prevailing at an interface between the top cell and the bottom cell can be discharged via the third contact. In both cases, the third contact electrically contacts the interface between the top cell and the bottom cell.It electrically contacts a side of the bottom cell that is opposite to the side contacted by the bottom contact and has an opposite polarity relative to the area of ​​the bottom cell contacted by the bottom contact, so that a voltage generated at the bottom cell can be tapped via the bottom contact and the third contact. In addition, the third contact electrically contacts a side of the top cell that is opposite to the side contacted by the top contact and has an opposite polarity relative to the area of ​​the top cell contacted by the top contact, so that a voltage generated at the top cell can be tapped via the top contact and the third contact. The third contact is referred to herein as the center tap contact, but can also be referred to as a Z contact (with "Z" for additional) according to the Warren convention. In conventional solar modules, each individual solar module typically has only one power input and one power output, via which the solar cells integrated into the solar module can be connected to an external circuit. Multiple solar modules can be connected in series and / or parallel via their individual power input and output connections to form a solar system. In contrast, the solar module described herein should have at least two power input terminals and / or at least two power output terminals. Preferably, each solar module should have at least two power input terminals and two power output terminals. However, at least theoretically, it is conceivable that a solar module serving as the first solar module within a solar system could have only one power input terminal but two power output terminals, or a solar module which serves as the last solar module within a solar system, has two power input connections but only one power output connection. The power input terminals and power output terminals are electrically connected in a special way to the terminal contacts of the various solar cells within the solar module. In particular, a first current input connection is electrically connected to at least one of the terminal contacts of the solar cell which is closest to the current input in the solar module, i.e. which has no further solar cell upstream of it on the current input side and which can therefore be regarded as the first solar cell of the solar module. A second current input connection is electrically connected to at least one of the terminal contacts of the solar cell which is adjacent to the first solar cell, i.e. to the second solar cell within the solar module. The first and second solar cells are components of one and the same string. Preferably, the first current input connection is directly electrically connected exclusively to the first solar cell. The second current input connection can be directly electrically connected exclusively to the second solar cell.Additionally, the second power input terminal can also be connected to one of the terminal contacts of the first solar cell, although this terminal contact is different from the terminal contact to which the first power input terminal is connected. Accordingly, there is no direct ohmic electrical connection between the first and second power input terminals. Similarly, a first current output connection is connected to at least one of the terminal contacts of a last solar cell closest to the current output, and a second current output connection is connected to at least one of the terminal contacts of a second-to-last solar cell adjacent to the last solar cell. The last and second-to-last solar cells are components of one and the same string. In this case, too, the first current output connection is preferably directly electrically connected exclusively to the last solar cell of the solar module. The second current output connection can be directly electrically connected exclusively to the second-to-last solar cell. In addition, the second current output connection can also be connected to one of the terminal contacts of the last solar cell, whereby this terminal contact, however, differs from the terminal contact with which the first current output terminal is connected. Accordingly, there is no direct ohmic electrical connection between the first and second current output terminals. The provision of at least two electrically separate current input connections and / or at least two separate current output connections and the special way in which these connections are connected to the various solar cells within the solar module makes it possible, among other things, for the various partial solar cells, i.e. the top cells and the bottom cells, to be advantageously interconnected within the solar module in such a way that within an entire solar system with several solar modules almost all of the partial solar cells can be operated optimally, i.e. they contribute to the overall efficiency of the solar system. In particular, string-end losses, which typically occur in each individual solar module of a solar system or even in each individual string in conventional solar modules with 3TT solar cells, can be largely avoided orTheir occurrence may be limited to a first solar module and / or a last solar module within a solar system comprising a plurality of solar modules. This will be further explained below with reference to specific exemplary embodiments. According to one embodiment, the top cell and bottom cell of each of the 3TT solar cells are arranged in an r-type configuration with reversed polarity. Furthermore, the first current input terminal is connected to the center tap of the first 3TT solar cell, and the second current input terminal is connected to the center tap of the second solar cell. Alternatively or additionally, the first current output terminal is connected to the top contact of the last 3TT solar cell, and the second current output terminal is connected to the top contact of the second-to-last 3TT solar cell. In other words, in this embodiment, the top cell and the bottom cell of a 3TT solar cell are oriented with opposite polarity, i.e., for example, the forward direction of the top cell is directed from the center tap contact to the top contact, and the forward direction of the bottom cell is directed from the center tap contact to the bottom contact. Such a configuration is also referred to as an r-type configuration, where "r" stands for "reverse." In contrast, in a so-called s-type configuration, the top solar cell and the bottom solar cell are similarly aligned and thus connected in series. The r-type configuration enables a particularly advantageous connection in the solar modules described herein. the 3TT solar cells with each other and with at least two current input terminals or at least two current output terminals. In particular, in this case, the first current input terminal can preferably be electrically contacted exclusively with the center tap contact of the first 3TT solar cell of the solar module. The second current input terminal is then electrically contacted with the center tap contact of the second 3TT solar cell of the solar module, wherein this second current input terminal can additionally be electrically contacted with the bottom contact of the first 3TT solar cell. Alternatively or additionally, the first current output terminal is preferably electrically contacted exclusively with the top contact of the last 3TT solar cell of the solar module. The second current output terminal is then electrically contacted with the top contact of the penultimate 3TT solar cell of the solar module, wherein this second current output terminal can additionally be electrically contacted with the bottom contact of the last 3TT solar cell of the solar module. The described r-type configuration together with the special way of connecting the terminals makes it possible to connect the 3TT solar cells to each other and to the multiple input and output terminals in an advantageous manner, in particular a manner with relatively few required electrical lines, in such a way that the occurrence of losses, in particular the occurrence of string-end losses, can be largely limited. This is especially true if the electrical voltages generated by the top cells and the electrical voltages generated by the bottom cells are in a certain relationship to each other. For example, according to one embodiment, the electrical voltage of the top cell generated upon exposure to light and the electrical voltage of the bottom cell generated upon exposure to light can essentially be in a ratio of m to n, where m and n are natural numbers. "Essentially" can be understood here, for example, to mean that the ratio of the electrical voltages actually generated between the top cell and the bottom cell differs from a ratio (m:n) by, for example, less than 25%, preferably less than 15%, more preferably less than 5%. In this case, n top cells connected in series can each be connected in parallel to m bottom cells connected in series. In other words, the top cell and the bottom cell can be designed, for example due to a suitable choice of materials and / or doping used for their production, such that their electrical voltages generated under common illumination, ie preferably their electrical voltages V mp p at the point of maximum power, are essentially in an integer relationship to each other. Accordingly, the n top cells connected in series can generate essentially the same voltage under illumination as the m bottom cells connected in parallel in series. The described adjustment of the voltages between the partial solar cells is also referred to as voltage-matched strings. According to a specific embodiment, m can be > 2 and n > 1. A number of current input terminals and / or a number of current output terminals then corresponds (in the case of an r-type configuration) to a larger of the two values ​​m and n or is (in the case of an s-type configuration) greater than the larger of the two values ​​m and n. In other words, a number of the current input terminals and / or current output terminals provided on the solar module can correlate with the way in which the top cells and the bottom cells are matched to each other with regard to the electrical voltages they generate and can thus be matched in groups of several series-connected top cells in parallel with groups of several series-connected bottom cells. According to a specific embodiment, for example, m=2 and n=1. In this case, with the exception of the last 3TT solar cell, each bottom contact of a solar cell can be connected to the center tap contact of the adjacent next 3TT solar cell, and, with the exception of the last and second-to-last 3TT solar cell, each top contact of a solar cell can be connected to the center tap contact of the next but one 3TT solar cell. Such a coordination of the voltages generated by the top cells and bottom cells in the ratio (2:1) together with the described interconnection of the top cells and bottom cells of the multiple 3TT solar cells can enable a particularly simple overall interconnection within the solar module while at the same time achieving high efficiency due to the avoidance of losses, in particular end losses. According to one embodiment, a first bypass diode is connected in parallel to the 3TT solar cells of the string in each of the strings. Furthermore, a second bypass diode is connected in parallel to the top cell of a last 3TT solar cell of the string in each of the strings. Like all diodes, bypass diodes only allow a significant amount of current to flow in one direction, i.e. in its forward direction. In solar modules, bypass diodes are typically connected in anti-parallel to the solar cells, e.g. in a string, so that in normal operating mode, i.e. when all solar cells are functioning correctly and generating current, they are polarized in the reverse direction. However, if one (or more) of the solar cells does not supply current, for example due to shading, it acts like an electrical load. The current generated by the other solar cells would have to flow through this load, which can generate considerable heat and lead to so-called hotspots. In addition, the total current flowing through a solar module generally depends on the weakest solar cell within the solar module, so that a single shaded solar cell could significantly limit the efficiency of the solar module.To avoid hot spots and reduced yields, bypass diodes are typically connected in parallel to strings of serially connected solar cells in solar modules. The reverse voltage of the bypass diode corresponds approximately to the open-circuit voltage of the solar cells connected in the string. In the solar modules made from 3TT solar cells described herein, as explained above, the individual top cells and bottom cells of the plurality of 3TT solar cells can be connected in such a way that a first number of top cells are connected in series with one another and a second number of bottom cells, different from these, are also connected in series, with both series connections being connected in parallel. For example, the top cells of the 3TT solar cells can be connected in series not with the top cell of a next-but-one 3TT solar cell, but only with the top cell of the next-but-one 3TT solar cell. In this case, a first bypass diode can be connected in parallel to the 3TT solar cells of a string. However, in the connection described, the top cell of the last 3TT solar cell in the string is not protected by this first bypass diode.Accordingly, it is advantageous to provide a separate, second bypass diode for this top cell, which is connected in parallel to this top cell. In principle, such a second bypass diode can have different properties than the first bypass diode, since it only needs to protect a single top cell. For example, the reverse voltage of the second bypass diode can be lower than that of the first bypass diode. However, it is also possible to design all bypass diodes in the solar module identically. According to a specific embodiment, the first bypass diode can be electrically connected, on the one hand, to the center tap contact of the first 3TT solar cell of the string and, on the other hand, to the bottom contact or the top contact of the last 3TT solar cell of the string. Furthermore, the second bypass diode can be electrically connected, on the one hand, to the top contact or the bottom contact of the last 3TT solar cell of the string and, on the other hand, to the center tap contact of the last 3TT solar cell of the string. Such a type of interconnection of the first and second bypass diodes can, as described below with reference to a specific embodiment, be particularly advantageous for a design of the solar module in which the three TT solar cells are designed in an r-type configuration and are matched to one another in a ratio (2:1) with regard to the voltages of their top cells and bottom cells. According to an alternative embodiment, the solar module can have at least one bypass diode connected across strings, wherein the bypass diode connected across strings is connected on the one hand to a 3TT solar cell in front of the last 3TT solar cell (ie, for example, a penultimate 3TT solar cell) of an adjacent substring and on the other hand to the last solar cell of the substring to be protected. In other words, in the solar module, the bypass diodes can be connected to the 3TT solar cells in such a way that at least one last 3TT solar cell in one of the substrings is connected to two bypass diodes, namely the bypass diode assigned to the respective substring and connected in parallel thereto, and the bypass diode assigned to an adjacent substring. The bypass diodes can be connected to the respective 3TT solar cell in such a way that at least one of the two bypass diodes protects the bottom cell and at least the other of the two bypass diodes protects the top cell of this 3TT solar cell. In this way, the provision of a separate bypass diode only for protecting a single top or bottom cell of a single 3TT solar cell, as discussed above with the second bypass diode, can be avoided. According to an alternative embodiment, the solar module can have at least one additional power input terminal and / or at least one additional power output terminal. At least one bypass diode to be interconnected across modules is accommodated in the solar module. The bypass diode to be interconnected across modules can be connected, on the one hand, to the additional power input terminal and, on the other hand, to one of the terminal contacts, in particular the bottom contact, of one of the 3TT solar cells in the solar module. Alternatively or additionally, the center tap contact of the last 3TT solar cell of the solar module can be connected to the additional power output terminal. With this design of the solar module, the previously described provision of a second bypass diode for protecting the top cell of a last 3TT solar cell in a string can be dispensed with. Instead, this top cell can be protected by the or one of the first bypass diodes of the subsequent string, i.e. a bypass diode connected in this way can act across strings. To do this, the subsequent first bypass diode contacts the last top cell of the previous string, for example, in the case of the r-type configuration, by contacting the center contact of the last cell in the string. However, if the top cell to be protected is that of the last 3TT solar cell not just within one of several strings in the solar module but the very last 3TT solar cell in the entire solar module, it cannot be protected by a first bypass diode from the same solar module.Instead, this top cell is also protected by a first bypass diode of a neighboring solar module. To enable cross-module interconnection of the bypass diode, at least one additional current input terminal and / or at least one additional current output terminal is provided on the solar module, via which the top cell can be interconnected with the first bypass diode in a neighboring solar module. An illustrative example of such a solar module configuration is presented below. According to a further specific embodiment, several 3TT solar cells are arranged side by side across the entire width of the solar module and electrically interconnected to form a substring. The first bypass diode and, if present, the second bypass diode are each arranged laterally next to the substring. In other words, the solar module can be designed with regard to the geometric arrangement of the 3TT solar cells accommodated therein such that several of the solar cells forming a substring are arranged side by side along the entire width of the solar module. Accordingly, the substring contains a relatively large number of solar cells connected in series. This type of interconnection in multi-cell substrings is particularly suitable when the individual solar cells each have a relatively high reverse voltage strength. In this case, it may be advantageous to arrange the first and second bypass diodes to the side of the substring, i.e., at an outer edge of the solar module. There, the bypass diodes can be particularly easily accessible and / or arranged in a space-saving manner, for example, in the area of ​​a solar module frame that locally covers the edge of the solar module. According to an alternative, specific embodiment, several 3TT solar cells are arranged laterally adjacent to one another across a first half of the width of the solar module and electrically interconnected to form a first substring, and several other 3TT solar cells are arranged laterally adjacent to one another across a second half of the width of the solar module and electrically interconnected to form a second substring. The first substring and the second substring are interconnected in parallel. Furthermore, the first bypass diode and, if present, the second bypass diode are each spatially arranged between the first substring and the second substring. In other words, the solar module can be designed with regard to the geometric arrangement of the solar cells accommodated therein such that only a relatively small number of solar cells are connected to form a substring. The solar cells connected to form a substring are geometrically arranged laterally next to one another in such a way that they extend across only half the width of the solar module. Therefore, two spatially adjacent substrings can be arranged next to one another across the entire width of the solar module. The two substrings are preferably connected in parallel. Since the number of solar cells within a substring is relatively small with this type of connection, this configuration is particularly suitable for cases where at least some of the partial solar cells have a relatively low reverse voltage strength. In this case, it may be advantageous to place the first and second bypass diodes geometrically between the first substring and the second substring. The bypass diodes can thus be arranged, for example, in or near a geometric center of the solar module. In this case, a single first bypass diode can be provided for the two substrings connected in parallel, which in turn is connected in parallel to both substrings. Furthermore, a separate second bypass diode can be provided for each of the two substrings, with a second bypass diode being connected anti-parallel to the top cell of the last 3TT solar cell in one of the two substrings and a further second bypass diode being connected anti-parallel to the top cell of the last 3TT solar cell in the other of the two substrings. Overall, due to the central arrangement of the bypass diodes between the substrings, a favorable overall wiring in the solar module can be achieved, for example with short connection distances and correspondingly low electrical resistance losses. According to a further specific embodiment, the first and, if present, the second bypass diode can be accommodated in a common diode box. A diode box can, for example, be a housing in which the bypass diodes can be accommodated and through which the bypass diodes can be protected, for example, from environmental influences. By accommodating both bypass diodes in a common diode box, the number of required diode boxes can be kept to a minimum. Furthermore, the design of the solar module with regard to the diode boxes to be provided therein can be the same or similar to that of conventional solar modules, which have only one bypass diode per solar cell string. Accordingly, the solar modules can be manufactured and / or assembled in the same way as conventional solar modules with regard to their diode boxes. According to one embodiment, the top cell is a perovskite solar cell and the bottom cell is a silicon solar cell. Silicon solar cells are known for their longevity, reliability, and high efficiency. For example, commercially available silicon solar cells can reliably deliver efficiencies well over 20% over a lifetime of 20 years or more. However, the efficiency of silicon solar cells is limited, among other things, by the relatively narrow band gap of silicon, meaning that high-energy light can generally only be converted into electrical energy with relatively high energy losses in the form of heat generation. More recently, perovskite solar cells have been developed, which can now also deliver high efficiency. Their longevity and reliability depend heavily on the precise composition of the perovskites used. Perovskites generally have a significantly larger band gap than silicon, for example, making them ideal for low-loss absorption of high-energy light. Accordingly, perovskite solar cells are ideally suited to serve as partners for silicon solar cells in tandem solar cells, where they can be used as top cells. The exact composition of the perovskites used correlates strongly with their band gap and thus indirectly with the open-circuit voltage delivered by the perovskite solar cell. In the approach described here for a solar system, perovskite solar cells can be used as top cells in the 3TT solar cells and optimized, for example, for their longevity and reliability. The electrical voltage of the top cells when illuminated depends on the perovskites used. Depending on the resulting electrical voltage, the interconnections within the solar module as well as the number of current input and output connections can be adjusted as described here in order to achieve favorable voltage matching between the top cells and the bottom cells within the solar module. According to one embodiment, the bottom solar cell may be a back contact solar cell in which terminal contacts of both polarities are arranged in an interleaved manner on a rear side of the bottom solar cell directed away from the top solar cell, wherein one of the terminal contacts of the bottom solar cell acts as the center tap contact. Back-contact solar cells, in which contacts of both polarities are arranged in an interleaved manner on a back side of a semiconductor substrate facing away from the light, have been known for a long time and are sometimes also referred to as IBC solar cells (interdigitated back contact). With suitable adaptation of the structures used in them, in particular the layer thicknesses, such back-contact solar cells can be adapted in such a way that they function as bottom cells in a tandem solar cell. The two types of contacts not only serve to extract the generated current from the bottom cell, but one of the contacts is also electrically connected to the top cell, for example via tunnel contacts, in such a way that, together with the top contact, the current generated in the top cell is also Current can be extracted. This contact acts as a center tap contact for the 3TT solar cell, but is not spatially located centrally between the top cell and the bottom cell, but rather on the back of the bottom cell. Corresponding concepts have already been presented, for example in the document [4] cited in the introduction to the description. Because the center tap contact is located on the back of the bottom cell, it can be manufactured relatively easily and contacted from the outside. This can significantly simplify the manufacture of 3TT solar cells and / or the interconnection of 3TT solar cells within the solar module. Embodiments of the solar modules described herein can be used to construct a solar system according to the second aspect of the present invention. The property that each solar module has at least two power input terminals and / or two power output terminals can be used to interconnect adjacent solar modules in such a way that losses such as string-end losses, which occur in conventionally designed and interconnected solar modules with 3TT solar cells, are largely avoided. For this purpose, each of the power output terminals of one of the solar modules is electrically connected to an associated power input terminal of the adjacent solar module.In other words, for example, the first current output of one solar module is connected to the first current input of the neighboring solar module and the second current output of the solar module is connected to the second current input of the neighboring solar module. As explained in more detail below using an exemplary embodiment, this prevents at least one of the first 3TT solar cells closest to the power input and / or one of the last 3TT solar cells closest to the power output in each of the solar modules from being operated in an optimal manner, thus resulting in the aforementioned end losses. Instead, due to the special interconnection proposed here between adjacent solar modules via the at least two output and input connections, such end losses no longer occur in each individual solar module, but ideally only in a first solar module and / or a last solar module of the entire solar system. Accordingly, the impact of these end losses on the efficiency of the entire solar system can be significantly reduced. According to one embodiment, with the exception of the power input terminals of a first of the solar modules and the power output terminals of a last of the solar modules, the power input terminals of each of the solar modules are electrically separated from each other and also the power output terminals of each of the solar modules are electrically separated from each other. Furthermore, according to one embodiment, in a first of the solar modules the at least two current input terminals are electrically short-circuited or connected to one another and / or in a last of the solar modules the at least two current output terminals are electrically short-circuited or connected to one another. In other words, each of the power input terminals of a solar module is electrically connected to only one of the power output terminals of the neighboring solar module, but not to the other power input terminal of the same solar module or the other power output terminal of the neighboring solar module. This preferably applies to all solar modules in the solar array with the exception of the first solar module and the last solar module. For these two solar modules, which are located at opposite ends of the series connection of solar modules within the solar array, the power input terminals of the first solar module and the power output terminals of the last solar module serve to connect the entire solar array to a single external circuit. Accordingly, these two "extremal" power input terminals and power output terminals are electrically connected to each other.Accordingly, end losses cannot be avoided at the first solar module and the last solar module, but are avoided at all solar modules in between. It should be noted that possible advantages and configurations of embodiments of the invention are described herein partly with reference to a solar module according to the invention or partly with reference to a solar system composed of several such solar modules. A person skilled in the art will recognize that the described features can be appropriately transferred, adapted, exchanged, or modified to achieve further embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are described below with reference to the accompanying drawings, wherein neither the drawings nor the description are to be construed as limiting the invention. Figs. l(a)-(d) illustrate an interconnection of 2TT solar cells, 4TT solar cells, 3TT solar cells in an s-type configuration and 3 TT solar cells in an r-type configuration. Fig. 2(a) shows a schematic cross-sectional view of a 3TT solar cell with a back contact solar cell as bottom cell in an r-type configuration. Fig. 2(b) shows a schematic cross-sectional view of a 3TT solar cell with a back contact solar cell as bottom cell in an s-type configuration. Fig. 3 illustrates a conventional interconnection of 3TT solar cells in an r-type configuration with occurring end losses. Fig. 4 illustrates a circuit in a solar module according to the invention with 3TT solar cells in an r-type configuration with two separate current input and output terminals and with several first and second bypass diodes. Fig. 5 illustrates two solar modules connected to form a solar system according to the invention. Fig. 6 illustrates a connection in a solar module according to the invention with 3TT solar cells in an r-type configuration with a bypass diode connected across strings and with three separate current input and output connections to enable a bypass diode to be connected across modules. Fig. 7 shows a geometric arrangement and connection of bypass diodes in a solar module according to the invention. Fig. 8 shows an alternative geometric arrangement and connection of bypass diodes in another solar module according to the invention. The figures are merely schematic and not to scale. Please note that the dimensions shown in the figures are not realistic. are merely intended to illustrate basic principles. Reference symbols denote identical or equivalent features in the various figures. DESCRIPTION OF PREFERRED EMBODIMENTS Multiple, stacked or tandem solar cells 1, as shown in various designs and interconnections in Figs. l(a)-(d) as partial regions of a respective solar module (19), offer the possibility of achieving significantly higher efficiencies than solar cells with only one pn junction due to the absorption of different spectral components in superimposed partial solar cells in the form of a top cell 3 and a bottom cell 5. If, as shown in Fig. 1(a), the partial solar cells 3, 5 are stacked on top of one another and connected in series to form 2-terminal tandem solar cells 7 (i.e., a cell with two connections or contacts), losses due to current mismatch can occur. The reasons for this are, on the one hand, that the band gaps of the two partial solar cells 3, 5 are usually not optimally selected due to technological conditions, and one partial solar cell generates a higher current than the other. The lower partial cell current then limits the total current of the 2TT solar cell. On the other hand, even with an optimal selection of the band gaps, current mismatch effects can occur, for example, due to a change in the irradiated spectrum. Losses due to current mismatch can be avoided if the individual solar cells 3, 5 are contacted and interconnected separately, as shown in Fig. 1(b). A tandem solar cell 1 has four terminals or contacts, i.e., two terminals for each solar cell 3, 5, and is therefore referred to as a 4-terminal tandem solar cell 9. This allows the individual solar cells 3, 5 to operate at their optimal operating point. However, this requires all solar cells to be processed, contacted, and interconnected separately, which generally requires increased effort and results in visual shading. Tandem solar cells 1 with three terminal contacts, i.e., 3TT solar cells 11, as shown in Figs. 1(c) and 1(d), also make it possible to significantly reduce losses due to current mismatch. Fig. 1(c) shows a so-called s-type configuration, in which the top cell 3 and the bottom cell 5 are polarized in the same direction and thus connected in series. Fig. 1(d) shows a so-called r-type configuration in which the top cell 3 and the bottom cell 5 are polarized in the opposite direction, ie "reverse". An attractive variant of a 3TT solar cell 11 offers the use of a bottom cell 5 as an IBC solar cell with two nested rear contacts and a contact on the front side that enables contact with the top cell 3. A concept for such a 3TT solar cell 11 is explained, for example, in the document [4] mentioned in the introduction to the description. Figs. 2(a) and 2(b) show embodiments of such a 3TT solar cell 11, with contact arrangement and designation following the convention of Warren et al. (see document [9] cited in the introduction to the description). Similar dopings are represented by similar hatching in the figures. 3TT solar cells can be manufactured in different types, which can be classified as "reverse" connection, i.e., an r-type configuration as shown in Fig. 2(a), and "series" connection, i.e., an s-type configuration as shown in Fig. 2(b). Due to the simpler connection, the "reverse" variant will be discussed primarily below. The terminal contacts of the 3TT solar cells 11 are designated according to their properties. The top contact 13, or T-contact, is the only accessible contact on the top cell 3.The top contact 13 contacts the side of the top cell 3 facing away from the bottom cell 5. The bottom contact 15, or R-contact (for "raiz" or "root"), is the contact of the two rear contacts of the bottom cell 5 with the opposite polarity of the front contact of the bottom cell. The bottom contact 15 contacts the side of the bottom cell 5 facing away from the top cell 3. The center tap contact 17, or Z-contact (for "additional"), is the rear contact with the same polarity as the front of the bottom cell, i.e., the additional contact for extracting the charge carriers. The center tap contact thus electrically contacts a side of the bottom cell 5 that is opposite the side contacted by the bottom contact 15 and has an opposite polarity relative to it.Thus, the center tap contact 17 is also capable of extracting charge carriers that were separated in the top cell 3 from the interface between the top cell 3 and the bottom cell 5. The center tap contact 17 can be geometrically arranged between the top cell 3 and the bottom cell 5; however, in the case of a rear-side contact similar to an IBC solar cell, the center tap contact 17 can alternatively be geometrically arranged on the rear side of the bottom cell 5, i.e., laterally adjacent to the bottom contact 15. and thereby act as electrically connected to the interface between the top cell 3 and the bottom cell 5. In Figs. 2(a) and 2(b) the electrical voltages prevailing between the various terminal contacts 13, 15, 17 are additionally indicated. Vt opis the voltage generated by top cell 3, and Vbot is the voltage generated by bottom cell 5. VRT is the voltage between bottom contact 15 and top contact 13, VZT is the voltage between center tap 17 and top contact 13, and VRZ is the voltage between bottom contact 15 and center tap 17. Advantages of 3TT solar cells include that (i) Solar modules formed in this way can be operated as bifacial tandem modules in open-field installations, since the top and bottom solar cells do not need to have the same current. This circumvents a major market entry barrier, since the additional yield of tandem modules must be measured not only against monofacial silicon modules but also against bifacial silicon modules. These have a higher yield than monofacial PV modules with the same efficiency of approximately 5%-20%, depending on the application and location; (ii) low losses are possible with a suboptimal band gap or voltage match at the maximum power point. This allows the selection of top cell 3 to be based on other criteria such as top cell reliability or efficiency; (iii) the voltage of each additional solar cell in a string of solar cells increases only by the voltage of the bottom cell and not by the combined voltage of the bottom and top cells. This allows for more photovoltaic modules per module string and thus requires fewer cables in the system structure. As illustrated in Figs. 1(c) and 1(d) as a partial view, 3TT solar cells 11 can be integrated into a solar module 19 through a combination of series and parallel connection. Since the top cells 3 generate a significantly higher voltage than the bottom cells 5, a single top cell 3, for example, is connected in parallel to two bottom cells 5. For this purpose, a top contact 13, i.e. a contact of the top cell 3 facing away from the bottom cell 5, is led to a contact of the opposite polarity of the next but one 3TT solar cell 11, which is a center tap contact 17. Since there is no 3TT solar cell 11 at the end of a string, losses occur there in the order of magnitude of the power of one to two 3TT solar cells, depending on Cell design or configuration and / or type of interconnection. The losses at the ends of the strings have been investigated theoretically, for example in the document [5] mentioned in the introduction to the description, and considerations for adjusting the voltage through the interconnection of the cells have been discussed since the introduction of 3TT solar cells, for example in the document [2] mentioned in the introduction to the description. One possible interconnection technology for 3T tandem PV modules was presented in document

[0010] . Accordingly, a practically implementable solution exists for interconnecting 3TT solar cells in the solar module. It should be noted that instead of interconnecting 3TT solar cells using a common connector structure, to which different terminal contacts of the 3TT solar cells are then connected orbe interconnected, as described in document

[0010] , alternatively continuous connectors can be used, by means of which typically adjacent solar cells within a module are contacted and interconnected, wherein usually a single connector is led from a front side of a 3TT solar cell to a back side of an adjacent 3TT solar cell. Fig. 3 shows a possible conventional interconnection of 3TT solar cells 11 in a combination of series and parallel connection for module integration. At each end of a string 21, there are two wiring ends 23. These are conventionally connected to each other by electrical connectors 25 in order to extract the current generated by the string 21 from the solar module 19 at a current input terminal 27 and a current output terminal 29. In other words, the connectors 25 at each string end ensure that the current generated in the string 21 can be extracted from the string 21. However, these connectors 25 short-circuit the bottom cell 5' of the first 3TT solar cell 11' of the string 21 (on the far left in Fig. 3) and its power is not extracted. Furthermore, at each string end, i.e. at the first 3TT solar cell 11' and the last 3TT solar cell 11", the top cell 3', 3" there is only operated at about 50% of its voltage. This leads to losses, also referred to as string-end losses, which in the case shown are equivalent to the power of approximately one 3TT solar cell. By connecting the wiring ends 23 to the connectors 25, a common bypass diode 31 can be connected in parallel to all 3TT solar cells 11 of the string 21, including all top cells 3 and all bottom cells 5. This means that string-end losses occur when integrating each bypass diode. This approach, with a currently typical string length of 20 Cells can experience a power loss of about 5%, which often more than compensates for the advantage of 3TT solar cells over, for example, 2TT solar cells. In the case of perovskite solar cells, often only a short string length per bypass diode is possible, making the impact of end losses even more significant. The approach discussed in this patent application discusses methods to transfer the string-end losses from a module level (with typically about 60 cells) or a substring level (typically a 1 / 3 module with about 20 cells) to a system level, e.g. a solar system (with typically up to 2000 cells), in order to minimize their relative contribution, and also addresses an advantageous possibility of integrating bypass diodes. In particular, embodiments of the invention address the following aspects: (i) An electrical connection between solar modules to a solar array using, for example, a two-core cable or two cables; (ii) Integration of bypass diodes without the need to join contacts or wiring ends at the end of strings; (iii) A modular design for modules in the middle and at the ends of strings by the external combination of contacts (e.g. module contacts combined outside the module), e.g. by suitable plugs or connectors. Fig. 4 illustrates an embodiment of a solar module 19 according to the invention, in which 3TT solar cells 11 are wired in a special manner to each other and to two current input terminals 27', 27" and two current output terminals 29', 29". Furthermore, at least one first bypass diode 33 and one second bypass diode 35 are provided in each of two substrings 21', 21" shown as examples. Fig. 5 illustrates how two solar modules 19 according to the invention can be interconnected to form a solar system 37 according to the invention. It should be noted that real solar systems generally comprise more than two solar modules 19, but that a wiring principle is clearly evident in this reduced example. With regard to the above aspect (i), Figs. 4 and 5 show the leading out of all string ends of different potentials to terminal contacts in the form of the two current input terminals 27 and current output terminals 29. This means that the substrings 21', 21" of several adjacent solar modules 19 are connected beyond the physical boundaries of the solar modules 1 to form an overall string. By connecting the solar modules 19 to one another via the two current input connections 27 and current output connections 29, it is possible to provide all top cells 3 in the overall string (with the exception of the top cell 3 of a very last 3TT solar cell 11) with a second but one bottom cell 5 for parallel connection and to extend the connection concept beyond the module boundaries. As a result, the string-end losses, which would otherwise occur in each of the substrings 21', 21" in parallel with a bypass diode 31 (i.e., with typically 20 or fewer cells each), are shifted to a system level (with typically up to 2000 or more cells) with a large number of interconnected solar modules 1, which results in a relative contribution of the string-end losses by two orders of magnitude (i.e.,from 1 / 20 = 5% to 1 / 2000 = 0.05%). Regarding aspect (ii) above, Figures 4 and 5 schematically show the integration of the first bypass diodes 33 and second bypass diodes 35. The first bypass diodes 33 (shown running down the figures) protect the respective substrings 21', 21", similar to a current 2TT solar cell or single-junction solar cell solar module. However, the last top cell 3" of each substring 21', 21" is not protected and is therefore protected by a separate second diode 35. At the end of the entire string, which extends over several solar modules 19 due to the described interconnection, the entire string ends 43 must generally be brought together for connection to a power electronics system or an inverter in order to enable the current generated from three parallel strings to be discharged. A first string comprises a first plurality of top cells 3, each connected in series, next to the next but one; a second string comprises a second plurality of top cells 3, each connected in series, likewise next to the next but one; and a third string comprises a plurality of bottom cells, each connected in series, next to the next but one. It should be noted that the examples shown in Figs. 3 to 5 apply to the case where the voltages Vt generated by the top cells 3 during illumination opare approximately twice as large as the voltages Vbot of the bottom cells 5, which means that the ratio Vtop / Vbot is an integer ratio (m : n), which in this specific case is equal to (2 : 1). Accordingly, the described circuitry includes n = 1 in series interconnected top cells 3, which are connected in parallel to m = 2 series-connected bottom cells 5. In this case, m = 2 parallel strings of series-connected top cells 3 are provided. It should be noted that in general the voltage ratios of the top and bottom cells can be matched in other ways in integer ratios m : n, e.g. Vt op / Vbot = (m : n) = (3 : 2) (not shown in the figures). Fig. 6 shows an alternative embodiment of a solar cell module 1, which differs from that of Figs. 4 and 5 in particular with regard to the provision and connection of bypass diodes and with regard to the manner in which this solar cell module 1 is to be connected to adjacent modules. In particular, this solar cell module 1 has a bypass diode 34 connected across the strings in the middle of the solar module 19. This is connected on the one hand to a penultimate cell 3TT solar cell 11' " in front of the last 3TT solar cell 11" of the preceding adjacent substring 21" and on the other hand to the last solar cell 11" of the substring 21' to be protected. In the example shown, the cross-string bypass diode 34 is connected to the bottom contact 15 of the penultimate 3TT solar cell 11'" of the preceding adjacent substring 21" on the one hand, and to the bottom contact 15 of the last solar cell 11" of the substring 21' to be protected on the other hand. In this way, the last solar cell 11" in the preceding adjacent substring 21" is connected both to the bypass diode 36 assigned to its substring" and to the cross-string bypass diode 34 assigned to the adjacent substring 21'.This also protects its top cell 3'", so that a second bypass diode 35, as proposed for the embodiment of Fig. 4, can be dispensed with. Furthermore, this solar cell module 1 has, in addition to the first and second current input terminals 27', 27", a further current input terminal 27"' and / or, in addition to the first and second current output terminals 29', 29", a further current input terminal 29"'. Furthermore, the solar module 1 has at least one bypass diode 36, which is connected in such a way that it can protect both 3TT solar cells 11 of the respective solar module 1 and at least one 3TT solar cell 11 of an adjacent solar module. This bypass diode is therefore also referred to herein as a bypass diode 36 to be connected across modules. In the example shown, this bypass diode 36, which is to be connected across modules, is electrically contacted on the one hand with the further current input connection 27"' and on the other hand with the bottom contact 15 of one of the 3TT solar cells 11 in the solar module 1. Furthermore, in addition to the bypass diode 36, which is to be connected across modules, the entire solar module also comprises a further bypass diode, which is connected as a cross-string bypass diode 34 as described above. This bypass diode 34 is connected between the center tap contact 17 of the 3TT solar cell 11" of the substring 11" shown on the left in the example, the bottom contact 15 of which is contacted by the cross-module bypass diode 36, and the bottom contact 15" of the last 3 TT solar cells 11" of the substring 21' shown on the left in the example.However, since this does not protect the top cell 3" of the last 3TT solar cell 11", the center tap contact 17" of this last 3 TT solar cell 11" is connected to the further current output connection 29". By connecting the additional power input terminal 27"' of adjacent solar modules 1 to the additional power output terminal 29"' of the adjacent solar module 1, the bypass diode 36 to be connected across modules can also protect the top cell 3" of the last 3TT solar cell 11" in the adjacent solar module 1. Therefore, the provision of one or more second bypass diodes 35 can be dispensed with in this embodiment. Figs. 7 and 8 show possible geometric arrangements of the bypass diodes 33, 35 in respective substrings 21 of a 3TT solar module 19 for 3TT solar cells 11 with high dielectric strength (Fig. 7) and low dielectric strength (Fig. 8). In the embodiment shown in Fig. 7, several 3TT solar cells 11 are arranged laterally next to one another in rows across the entire width B of the solar module 19, wherein in the example shown, two such rows are electrically connected to form a substring 21'. The first bypass diode 33 and the second bypass diode 35 are each arranged laterally next to the substring 21'. The bypass diodes 33, 35 can be arranged, for example, near a lateral edge of the solar module 19, for example on or below a frame enclosing the solar module 19 (not shown). In the figure, the squares represent the 3TT solar cells 11. The lines 39 along the edge of the 3TT solar cells 11 symbolize a 3-pole connection between the solar cells. A practical solution for this 3-pole connection was explained in

[0010] . Vertical Hatched dots symbolize a bottom contact 15 (R contact) to bottom cell 5, horizontally hatched dots symbolize a top contact 13 (T contact) to top cell 3, diagonally hatched dots symbolize a center tap contact 17 (Z contact) of the 3TT solar cell 11. To keep the contact diagram for the bypass diodes 33, 35 simple, only the contacts to the geometrically closest 3TT solar cell 11 are shown. By interconnecting the 3TT solar cells 11 (symbolized by line 39), the terminal contacts are continued to other 3TT solar cells 11 in string 21. This arrangement has two parallel rows of solar cells that are connected in series. This geometric arrangement is suitable for solar cells with high reverse voltage strength. In the embodiment shown in Fig. 8, however, a plurality of 3TT solar cells 11 are arranged laterally next to one another over a first half B / 2 of a width B of the solar module 19 and are electrically connected to a first substring 21', and a plurality of other 3TT solar cells are arranged laterally next to one another over a second half of the width of the solar module 19 and are electrically connected to a second substring 21". The first substring 21' and the second substring 21" are connected in parallel to one another. The first bypass diode 33 and the second bypass diode 35 are each arranged laterally between the first substring 21' and the second substring 21". This type of connection is particularly suitable for 3TT solar cells 11 with low reverse voltage strength. In other words, as with half-cell modules, the bypass connection for 3TT solar cells 11 with low reverse voltage strength can be made in the center of the module (Fig. 8). However, the 3TT solar cells 11 are virtually connected in series within a double string (symbolized by the encircling line 39). From the outgoing contacts, further connection can be made either to the next substring 21 or to the next solar module 19. A center contact 17 (Z-contact) is tapped from a 3TT solar cell 11 not located directly in the center of the module. This contact is established via a wire connection, which is usually routed to the next top cell 3 for further connection. This connection can be used as a current tap. The special feature of the geometric arrangement of solar cells 11 and bypass diodes 33, 35 in Fig. 7 is that two of the bypass diodes 33, 35 located next to a double string 21 can be combined in a common diode box 41 (shown in dashed lines in Fig. 7 for reasons of clarity). For example, it is possible to use the usual three Diode boxes 41 to construct a solar module 19. Similarly, with the geometric arrangement of solar cells 11 and bypass diodes 33, 35 in Fig. 8, two bypass diodes 33, 35 can be interconnected in each diode box (not shown in Fig. 8 for reasons of clarity), so that it is again possible to implement the diode interconnection with the usual three diode boxes 41 in the center of the module. If the proposed solar modules 19 are connected together, it is optionally possible, while accepting string-end losses, to short-circuit the two current output connections 29', 29" to a common negative contact and the two current input connections 27', 27" to a common positive contact in order to achieve only a single-wire connection between the solar modules 19. In this case, the solar modules 19 are wired in series with one another in such a way that the negative contact is connected to a positive contact of an adjacent solar module 19. If the full potential of the connection is to be exploited, a first current output connection 29' must be connected in series with a first current input connection 27' and a second current output connection 29" must be connected in series with a second current input connection 27" of an adjacent solar module 19 via a two-wire connection, e.g. with a two-wire cable or with two cables. It should be noted that terms such as "having," "comprising," etc., do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations. LIST OF REFERENCE SYMBOLS I Tandem solar cell 3 top cells 3' top cell of the first 3TT solar cell 3" top cell of the last 3TT solar cell 5' bottom cell of the first 3TT solar cell 5" bottom cell of the last 3TT solar cell 5 Bottom cell 7 2TT solar cell 9 4TT solar cell II 3TT solar cell 11 ' first 3TT solar cell 11" last 3TT solar cell 13 top contacts 15 Bottom contact 17 Center tap contact 19 solar module 21 strings 21' Substring 21" Substring 23 wiring ends 25 connectors 27 Power input connector 27 ' first power input connection 27" second power input connection 27 “ ' additional power input connection 29 Power output connector 29 ' first power output connection 29" second power output connection 29 “ ' additional power output connection 31 common bypass diode 33 first bypass diode 34 cross-string interconnected bypass diodes 35 second bypass diode 36 Bypass diode to be connected across modules 37 Solar system 39 Line symbolizing series connection 41 Diode box 43 total string ends

Claims

AMENDED CLAIMS received by the International Bureau on 27 February 2024 (27.02.2024) amended claims:

1. A solar module (19) comprising: a plurality of 3TT solar cells (11) interconnected to form at least one string (21), and at least two current input terminals (27) at a current input of the solar module (19) and / or at least two current output terminals (29) at a current output of the solar module (19), wherein each 3TT solar cell (11) comprises a stack with a top cell (3) and a bottom cell (5) arranged thereunder, wherein the top cell (3) and the bottom cell (5) differ from one another with respect to an electrical voltage generated upon exposure to light, wherein each 3TT solar cell (11) comprises three terminal contacts with a top contact (13) electrically contacting a side of the top cell (3) facing away from the bottom cell (5), a bottom contact (15) electrically contacting a side of the bottom cell (5) facing away from the top cell (3), and a center tap contact (17),which electrically contacts the 3TT solar cell at an interface between the top cell (3) and the bottom cell (5), wherein a first (27') of the current input terminals (27) is connected to at least one of the terminal contacts of a first (11') of the 3TT solar cells (11) closest to the current input, and wherein a second (27") of the current input terminals (27) is connected to at least one of the terminal contacts of a second of the 3TT solar cells (11) adjacent to the first 3TT solar cell (11'), and / or wherein a first (29') of the current output terminals (29) is connected to at least one of the terminal contacts of a last (11") of the 3TT solar cells (11) closest to the current output, and wherein a second (29") of the current output terminals (29) is connected to at least one of the terminal contacts of a penultimate solar cell adjacent to the last 3TT solar cell (11"). 3TT solar cells (11), wherein, (i) in each of the strings (21) a first bypass diode (33) is connected in parallel to the 3TT solar cells (11) of the string (21) and wherein further in each of the strings (21) a second bypass diode (35) is connected in parallel to the top cell (3) and / or bottom cell (5) of a last 3TT solar cell (11') of the string (21), and / or (ii) the solar module (19) has at least one bypass diode (34) connected across strings, wherein the bypass diode (34) connected across strings is connected on the one hand to a 3 TT solar cell (11") in front of the last 3TT solar cell (11") of an adjacent substring (21") and on the other hand to the last solar cell (11") of the substring (21') to be secured.

2. Solar module according to claim 1, wherein the top cell (3) and the bottom cell (5) of each of the 3TT solar cells (11) are arranged in an r-type configuration with reversed polarity, and wherein the first current input terminal (27') is connected to the center tap contact (17) of the first 3TT solar cell (11') and the second current input terminal (27") is connected to the center tap contact (17) of the second solar cell (11) and / or wherein the first current output terminal (29') is connected to the top contact (3) of the last 3TT solar cell (11") and the second current output terminal (29") is connected to the top contact (3) of the second-to-last 3TT solar cell (11).

3. Solar module according to one of the preceding claims, wherein the electrical voltage of the top cell (3) generated upon light irradiation and the electrical voltage of the bottom cell (5) generated upon light irradiation are substantially in a ratio of m to n, where m and n are natural numbers, and where n series-connected top cells (3) are connected in parallel to m series-connected bottom cells (5).

4. Solar module according to claim 3, wherein m ≥ 2 and wherein n ≥ 1, and wherein a number of the current input terminals (27) and / or a number of the current output terminals (29) is equal to or greater than a larger of the two values ​​n and m.

5. Solar module according to one of claims 3 and 4, wherein m=2 and n=1, wherein, with the exception of the last 3TT solar cell (11 ”), each bottom contact (15) of a 3TT solar cell (11) is connected to the center tap contact (17) of the adjacent next 3TT solar cell (11), and wherein, with the exception of the last and the penultimate 3TT solar cell, each top contact (3) of a 3TT solar cell (11) is connected to the center tap contact (17) of the next but one subsequent 3TT solar cell (11).

6. Solar module according to claim 1, wherein in each of the strings (21) a first bypass diode (33) is connected in parallel to the 3TT solar cells (11) of the string (21), and wherein further in each of the strings (21) a second bypass diode (35) is connected in parallel to the top cell (3) and / or bottom cell (5) of a last 3TT solar cell (11') of the string (21), and wherein the first bypass diode (33) is electrically connected on the one hand to the center tap contact (17) of a first 3TT solar cell (11') of the string (21) and on the other hand to the bottom contact (15) or the top contact (13) of the last 3TT solar cell (11") of the string (21), and wherein the second bypass diode (35) is electrically connected on the one hand to the top contact (13) or the bottom contact (15) of the last 3TT solar cell (11") of the string (21) and on the other hand is electrically connected to the center tap contact (17) of the last 3TT solar cell (11") of the string (21).

7. Solar module according to one of the preceding claims, wherein the solar module (19) has at least one further current input connection (27") and / or at least one further current output connection (29"), wherein at least one bypass diode (36) to be interconnected across modules is accommodated in the solar module (19), wherein the bypass diode (36) to be interconnected across modules is connected on the one hand to the further current input connection (27") and on the other hand to one of the Terminal contacts, in particular with the bottom contact (15), one of the 3 TT solar cells (11) is connected in the solar module (19) and / or wherein the center tap contact (17) of the last 3TT solar cell (11) of the solar module (19) is connected to the further current output connection (29").

8. Solar module according to one of the preceding claims, wherein a plurality of 3 TT solar cells (11) are arranged laterally next to one another over an entire width (B) of the solar module (19) and are electrically connected to form a substring (21'), and wherein the first bypass diode (33) and, optionally, the second bypass diode (35) are each arranged laterally next to the substring (21').

9. Solar module according to one of the preceding claims, wherein a plurality of 3TT solar cells (11) are arranged laterally next to one another over a first half of a width (B) of the solar module (19) and are electrically connected to form a first substring (21'), and a plurality of 3TT solar cells (11) are arranged laterally next to one another over a second half of the width of the solar module (19) and are electrically connected to form a second substring (21"), wherein the first substring (21') and the second substring (21") are connected in parallel to one another, and wherein the first bypass diode (33) and, optionally, the second bypass diode (35) are each arranged between the first substring (21') and the second substring (21").

10. Solar module according to one of the preceding claims, wherein the first and second bypass diodes (33, 35) are accommodated in a common diode box (41).

11. Solar module according to one of the preceding claims, wherein the top cell (3) is a perovskite solar cell and the bottom cell (5) is a silicon solar cell.

12. Solar module according to one of the preceding claims, wherein the bottom solar cell (5) is a back contact solar cell, in which terminal contacts (15, 17) of both polarities are arranged in an interleaved manner on a rear side of the bottom solar cell (5) directed away from the top solar cell (3), and wherein one of the terminal contacts of the bottom solar cell (5) acts as the center tap contact (17).

13. Solar system comprising: several solar modules (19) according to one of the preceding claims, wherein in adjacent solar modules (19) each of the current output terminals (29) one of the solar modules (19) is electrically connected to an associated one of the current input terminals (27) of the adjacent one of the solar modules (19).

14. Solar system according to claim 13, wherein, with the exception of the power input terminals (27) of a first of the solar modules (19) and the power output terminals (29) of a last of the solar modules (19), the power input terminals (27) of each of the solar modules (19) are electrically insulated from one another and the power output terminals (29) of each of the solar modules (19) are electrically insulated from one another.

15. Solar system according to one of claims 13 and 14, wherein in a first of the solar modules (19) the at least two current input terminals (27) are electrically short-circuited or connected to one another and / or wherein in a last of the solar modules (19) the at least two current output terminals (29) are electrically short-circuited or connected to one another.

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