Solar module with three-terminal tandem solar cells

Abstract

A solar module (19) and solar collector (37) constructed using a plurality of solar modules are described. The solar module comprises a plurality of 3TT solar cells (11) interconnected to form at least one string (21), at least two current input connections (27) at the current input of the solar module, and / or at least two current output connections (29) at the current output of the solar module. Each 3TT solar cell has a stack having a top cell (3) and a bottom cell (5) disposed therebelow. Each 3TT solar cell has terminal contacts: a top contact (13), a bottom contact (15), and a center tap contact (17). The first (27') of the current input connections (27) is connected to at least one terminal contact of the first (11') of the 3TT solar cells closest to the current input, the second (27') of the current input connections (27) is connected to at least one terminal contact of the second 3TT solar cell adjacent to the first 3TT solar cell, and / or the first (29') of the current output connections is connected to at least one terminal contact of the last (11'') of the 3TT solar cells closest to the current output, and the second (29'') of the current output connections is connected to at least one terminal contact of the penultimate 3TT solar cell adjacent to the last 3TT solar cell. The described wiring makes it possible, inter alia, to significantly prevent end-of-string losses and also allows for advantageous integration of bypass diodes (33, 35).

Description

[Technical Field]

[0001] The present invention relates to a solar module comprising tandem solar cells. [Background technology]

[0002] Solar modules serve, inter alia, to convert light emitted by the sun into electrical energy. Solar modules of this type are also called photovoltaic modules or PV modules. In this case, the solar module comprises a number of solar cells interconnected in series and / or parallel. Conventionally, solar modules also comprise current input and current output connections so that the solar module can be connected in series and / or parallel to further solar modules to form a solar collector and so that the electrical energy generated by the solar module can ultimately be supplied to an external electrical circuit with connected consumers.

[0003] Traditionally, solar modules have typically utilized solar cells in which pairs of charge carriers generated by the absorption of incident light are separated by a single potential difference, for example, created by a pn junction. In this case, the power or efficiency of the solar cell depends, among other things, on the potential difference and, therefore, on the (semiconductor) material used to generate the potential difference. In this case, the efficiency of the solar cell is limited, among other things, by the fact that, depending on the band gap of the semiconductor material used, the low-energy portion of the emitted light is not absorbed, and the high-energy portion can only be converted into electrical energy with significant energy losses.

[0004] To increase the efficiency of solar cells, solar cells have been developed that stack two or more partial solar cells. This type of solar cell is called a tandem solar cell, or sometimes called a multiple solar cell or stacked solar cell. In this case, the two partial solar cells are made of different materials and therefore have different bandgaps. In this case, the partial solar cell facing the incident light, also called the top cell, usually has a larger bandgap and is therefore configured to absorb and convert the high-energy portion of the incident light with relatively low energy loss. The additional partial solar cell located below it, also called the bottom cell, has a smaller bandgap and is therefore configured to absorb and convert the low-energy portion of the incident light with relatively low energy loss.

[0005] Tandem solar cells are preferably constructed monolithically. That is, they are designed as a single part in which all components, such as the various semiconductor layers and contacts, are firmly interconnected. For this purpose, for example, multiple layers can be deposited one on top of the other over the entire surface and / or in partial areas. In this case, the tandem solar cell has at least two terminal contacts, but, as explained below, in some implementations, it has three, four, or more terminal contacts. In this case, terminal contacts are understood to be electrical contacts on the tandem solar cell that are externally accessible and allow the solar cell or its partial solar cells to be electrically connected to other solar cells or their partial solar cells.

[0006] In this case, various connection configurations for tandem solar cells are known.

[0007] Two-terminal tandem solar cells, also known as 2TT solar cells, have only two terminal contacts: a top contact, typically located on the front of the tandem solar cell, and a bottom contact, typically located on the rear. These types of 2TT solar cells can be easily connected within a solar module, essentially in the same way as conventional non-tandem solar cells. However, the fact that the total current flowing through a 2TT solar cell must be the same for both partial solar cells means that the current is limited by the weaker of the two partial solar cells. This regularly results in losses due to current mismatch. This can be because, on the one hand, the bandgaps of the two partial solar cells are not optimally selected due to technological boundary conditions, resulting in one partial solar cell generating a higher current than the other, while the weaker partial solar cell's lower current limits the total current of the tandem solar cell. On the other hand, even when the bandgaps are optimally selected, current mismatch effects can occur due to changes in the emitted light spectrum.

[0008] Losses due to current mismatch can be largely prevented if the individual partial solar cells of a tandem solar cell can be contacted and connected separately. To this end, the tandem solar cell may be provided with four terminal contacts, i.e., configured as what is known as a 4TT solar cell. In this case, each individual partial solar cell has two terminal contacts and can therefore operate at its optimal operating point independently of the other partial solar cells. However, to achieve this, every partial solar cell must be individually processed, contacted, and connected, which increases costs and can result in increased optical shading.

[0009] As a similar intermediate step between 2TT and 4TT solar cells, tandem solar cells with three terminal contacts have been developed and are therefore called 3TT solar cells. In addition to the top and bottom contacts, 3TT solar cells have an additional terminal contact called a center tap contact. This contact connects 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. As a result, 3TT solar cells allow for electrical connections within a solar module, which can significantly reduce losses due to current mismatch. On the other hand, the connections of 3TT solar cells within a module are less complex than those of 4TT solar cells, and / or losses due to optical shading due to multiple terminal contacts can be less compared to 4TT solar cells.

[0010] 3TT solar cells and the solar modules constructed using them have been studied theoretically and experimentally for a long time. Considerations and findings regarding their internal structure and their arrangement and connection in solar modules are described, inter alia, 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), pp. 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

[10] 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 / 1.5053521, Published Online: 13 September 2018

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

[12] 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

[0011] It has been observed that efficiency or power yield can be non-optimal for solar modules constructed using 3TT solar cells, i.e., can be particularly lower than expected depending on the efficiency of the individual solar cells and the number of solar cells in the solar module. Summary of the Invention

[0012] Summary of the Invention and Embodiments Therefore, there may be a need for solar modules that enable higher efficiency or power yield. In particular, there may be a need for solar modules based on 3TT solar cells, where high efficiency of individual solar cells results in high efficiency of the overall solar module through appropriate selection of the solar cell configuration within the solar module. Furthermore, there may be a need for high-efficiency solar collectors that accompany this type of solar module.

[0013] The above needs may be met at least in part by the subject matter of one of the independent claims of the present application. Advantageous embodiments are specified in the dependent claims and in the following description and drawings.

[0014] According to a first aspect of the present invention, a solar module is described, comprising a plurality of 3TT solar cells, at least two current input connections at a current input of the module, and / or at least two current output connections at a current output of the module. In this case, the 3TT solar cells are interconnected to form at least one string. Each 3TT solar cell has a stack having a top cell and a bottom cell disposed thereunder, the top cell and bottom cell generating different voltages when exposed to light. Each 3TT solar cell has three terminal contacts: a top contact electrically contacting the side of the top cell opposite the bottom cell, a bottom contact electrically contacting the side of the bottom cell opposite the top cell, and a center tap contact electrically contacting the 3TT solar cell at the interface between the top cell and the bottom cell. A first of the current input connections 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 connections 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 one of the current output connections is connected to at least one of the terminal contacts of the last one of the 3TT solar cells closest to the current output, and a second one of the current output connections is connected to at least one of the terminal contacts of the penultimate one of the 3TT solar cells adjacent to the last 3TT solar cell.

[0015] According to a second aspect of the present invention, a solar collector is described comprising a plurality of solar modules according to an embodiment of the first aspect of the present invention, wherein each current output connection of one of the solar modules is electrically connected to an associated one of the current input connections of an adjacent one of the solar modules.

[0016] By way of preamble, basic concepts related to the embodiments of the invention described herein will be briefly explained; this explanation is intended to be merely a general overview and is not intended to be limiting of the invention.

[0017] The present invention particularly describes a solar module that, thanks to a special type of arrangement and connection of the 3TT solar cells housed therein, can largely prevent losses, known in particular as end-of-string losses, that occur in conventional solar modules in which the 3TT solar cells are arranged and connected in a conventional manner. As will be explained in more detail below, in this case, the main feature of the solar module defined herein is considered to be the fact that the solar module does not simply have one current input connection and one current output connection, as is typical for conventional solar modules, but rather in each case includes two or more current input and output connections, which are connected in a specific manner to the 3TT solar cells in the solar module. Due to the special type of connection and the multiple current input and output connections, in this case, end-of-string losses due to partial solar cells that do not contribute, or do not optimally contribute, to the efficiency of the module due to their connection are no longer caused on each connected solar cell string, i.e., at least once within each solar module. Instead, multiple solar modules may be interconnected such that the corresponding end losses are induced only once across the multiple solar modules, thus having a significantly reduced impact on the overall efficiency of the solar collector.Furthermore, an embodiment of a solar module comprising 3TT solar cells is described in which appropriate connection of bypass diodes ensures reliable operation of the solar module and at the same time makes it possible to prevent the above-mentioned end losses.

[0018] Possible implementations and advantages of embodiments of the solar module and methods for manufacturing said module are explained in more detail below.

[0019] As described herein, a solar module includes a plurality of solar cells in the form of 3TT solar cells. For example, a solar module typically includes more than 10 solar cells, typically more than 50 solar cells, but typically includes less than 300 solar cells, typically less than 150 solar cells. An individual solar cell is a two-dimensionally formed diode, typically having a surface area of ​​10 cm or less. 2 ~1000cm 2 , usually 100cm 2 ~500cm 2 The thickness of a solar cell is typically in the range of 10 μm to 1000 μm, usually 50 μm to 400 μm. At least a portion of the solar cell may be based on a crystalline, i.e., monocrystalline, multicrystalline, or polycrystalline, semiconductor substrate, such as a silicon wafer. Alternatively, or additionally, a portion of the solar cell may be formed of an amorphous semiconductor material, for example in the form of one or more thin films.

[0020] Solar cells are connected to form one or more strings. In this case, the entire solar cell or the partial solar cells forming said solar cell may be interconnected in series and / or parallel. In this case, a string is understood to be the smallest unit of interconnected solar cells, and the entire solar module may comprise several such strings interconnected in series and / or parallel. In this case, the number of solar cells that can be combined in a string depends on various influencing factors. In particular, this number is typically selected so that the voltage generated by the string during illumination does not exceed the reverse electrical strength of each individual solar cell in the string. Typically, such a string comprises 3 to 50 solar cells connected in series, usually 6 to 30 solar cells connected in series.

[0021] A 3TT solar cell installed in a solar module is composed of a first partial solar cell and a second partial solar cell. The first partial solar cell is located on the side of the solar cell that faces incident light during use, and this side is considered the upper side, so the first partial solar cell is called the top cell. The second partial solar cell is located below the first partial solar cell and is called the bottom cell. Each partial solar cell may have a single pn junction, or if a special cell design is used, multiple pn junctions, which are preferably arranged back to back along the direction of incident light.

[0022] The top and bottom cells differ in the semiconductor materials from which they are formed. For example, the semiconductor material of the top cell typically has a larger energy bandgap than that of the bottom cell, and the two bandgaps can differ from each other by more than 20%, preferably more than 40%, or even more than 80%. The different bandgaps result in different voltages being established in the two partial solar cells under illumination due to potential differences (e.g., through the respective pn junctions) formed in each case by appropriate local doping. In other words, the off-load voltages (open circuit voltages V OC (sometimes called the V OC may be 30% or more, 50% or more, or even 100% or more greater than that of the bottom cell.

[0023] Each 3TT solar cell has exactly three terminal contacts through which it is connected to other 3TT solar cells. In this case, the terminal contacts are generally formed by a conductive layer, such as a metal layer, attached to or integrated into the solar cell. In this case, the terminal contacts may be formed in a single layer, but multiple terminal contacts may be composed of multiple partial regions or partial layers.

[0024] The three terminal contacts can be designated according to the convention introduced by Warren et al. (See reference [9] in the list of references cited at the beginning of this specification). In this case, the first contact is typically located on the front side of the solar cell facing the incident light and electrically contacts the side of the top cell opposite the bottom cell ("electrically contacting" is intended to be understood herein generally as direct electrical contact, i.e., without the intermediary of other electrical components, i.e., particularly as an ohmic contact). The first contact is referred to herein as the top contact, but may also be referred to as the T contact ("T" for top) following the convention adopted by Warren. The second contact is typically located on the rear side of the solar cell opposite the incident light and electrically contacts the side of the bottom cell opposite the top cell. The second contact is referred to herein as the bottom contact, but may also be referred to as the R contact ("R" for root) following the convention adopted by Warren. The third contact may, for example, be located in a plane between the top and bottom cells. However, as described in more detail below, the third contact may be spatially disposed on the rear side of the solar cell, and the bottom cell and third contact may be configured so that current present at the interface between the top cell and the bottom cell is discharged through the third contact. In either case, the third contact electrically contacts the interface between the top cell and the bottom cell. In this case, it electrically contacts the side of the bottom cell opposite the side contacted by the bottom contact and having the opposite polarity to the region of the bottom cell contacted by the bottom contact, so that the voltage generated in the bottom cell can be tapped through the bottom contact and the third contact. Furthermore, the third contact electrically contacts the side of the top cell opposite the side contacted by the top contact and having the opposite polarity to the region of the top cell contacted by the top contact, so that the voltage generated in the top cell can be tapped through the top contact and the third contact.The third contact is referred to herein as a center tap contact, but may also be referred to as a Z contact ("Z" from zusaetzlich) ("extra" or "additional" in English), following the convention adopted by Warren.

[0025] In conventional solar modules, each solar module typically has only one current input connection and only one current output connection, via which the solar cells integrated within the solar module can be connected to an external electrical circuit. In this case, multiple solar modules may be interconnected in series and / or in parallel via their individual current input and output connections to collectively form a solar collector.

[0026] In contrast, the solar modules described herein are intended to have at least two current input connections and / or at least two current output connections. Preferably, each solar module should have at least two current input connections and two current output connections. However, at least in theory, a solar module serving as the first solar module in a solar collector could have only one current input connection but two current output connections, or a solar module serving as the last solar module in a solar collector could have two current input connections but only one current output connection.

[0027] In this case, the current input and output connections are electrically connected in a special way to the terminal contacts of the various solar cells in the solar module.

[0028] In particular, the first current input connection is electrically connected to at least one terminal contact of a solar cell that is closest to the current input in the solar module, i.e., that has no additional solar cells upstream on the current input side and can therefore be considered the first solar cell of the solar module. The second current input connection is electrically connected to at least one terminal contact of a solar cell adjacent to the first solar cell, i.e., the second solar cell in the solar module. In this case, the first and second solar cells are components of the same string. Preferably, the first current input connection is electrically connected directly only to the first solar cell. The second current input connection may also be electrically connected directly only to the second solar cell. The second current input connection may also be connected to one of the terminal contacts of the first solar cell, but this terminal contact is different from the terminal contact to which the first current input connection is connected. Therefore, there is no direct ohmic electrical connection between the first current input connection and the second current input connection.

[0029] Similarly, the first current output connection is connected to at least one of the terminal contacts of the last solar cell closest to the current output, and the second current output connection is connected to at least one of the terminal contacts of the penultimate solar cell adjacent to the last solar cell. In this case, the last solar cell and the penultimate solar cell are components of the same string. Again, preferably, the first current output connection is directly electrically connected only to the last solar cell of the solar module. The second current output connection may also be directly electrically connected only to the penultimate solar cell. The second current output connection may also be connected to one of the terminal contacts of the last solar cell, but this terminal contact is different from the terminal contact to which the first current output connection is connected. Therefore, there is no direct ohmic electrical connection between the first current output connection and the second current output connection.

[0030] Providing at least two electrically separate current input connections and / or at least two separate current output connections, as well as a special way in which these connections are connected to the various solar cells in the solar module, allows, among other things, different partial solar cells, i.e., top and bottom cells, to be interconnected within the solar module in an advantageous way, such that almost all partial solar cells can be optimally operated within the overall solar collector having multiple solar modules, i.e., can contribute to the overall efficiency of the solar connector. In particular, end-of-string losses that typically occur in individual solar modules or even individual strings of a solar collector in the case of conventional solar modules with 3TT solar cells can be largely prevented or their occurrence can be limited to the first solar module and / or the last solar module in a solar collector including multiple solar modules. This will be explained in more detail below with reference to specific embodiments.

[0031] According to one embodiment, the top and bottom cells of each of the 3TT solar cells are arranged in an R-type configuration with reverse polarity. Further, the first current input connection is connected to the center tap contact of the first 3TT solar cell, and the second current input connection is connected to the center tap contact of the second solar cell. Alternatively or additionally, the first current output connection is connected to the top contact of the last 3TT solar cell, and the second current output connection is connected to the top contact of the penultimate 3TT solar cell.

[0032] In other words, in this embodiment, the top and bottom cells of the 3TT solar cells are oriented with opposite polarities, i.e., for example, the forward direction of the top cell is from the center tap contact to the top contact, and the forward direction of the bottom cell is from the center tap contact to the bottom contact. This type of embodiment is called an r-type configuration, where "r" stands for "reverse." In contrast, in what is known as an s-type configuration, the top and bottom solar cells are oriented identically and are therefore connected in series. In the solar modules described herein, the r-type configuration allows for particularly advantageous connection of the 3TT solar cells to each other and to at least two current input connections or at least two current output connections, respectively.

[0033] In particular, in this case, the first current input connection may preferably be electrically contacted only by the center tap contact of the first 3TT solar cell of the solar module. The second current input connection may then be electrically contacted with the center tap contact of the second 3TT solar cell of the solar module, with the second current input connection additionally being electrically contacted with the bottom contact of the first 3TT solar cell. Alternatively or additionally, the first current output connection may preferably be electrically contacted only with the top contact of the last 3TT solar cell of the solar module. The second current output connection may then be electrically contacted with the top contact of the penultimate 3TT solar cell of the solar module, with the second current output connection additionally being electrically contacted with the bottom contact of the last 3TT solar cell of the solar module.

[0034] The above-described r-type configuration, together with the special method of connecting the connections, makes it possible to connect 3TT solar cells to each other and to multiple input and output connections in an advantageous manner, in particular in a manner requiring a relatively small number of electrical wires, so that the occurrence of losses, in particular the occurrence of end-of-string losses, can be significantly limited.

[0035] This is especially true when the voltages produced by the top cell and the bottom cell are in a particular ratio to each other.

[0036] For example, according to one embodiment, the voltage of the top cell generated when exposed to light and the voltage of the bottom cell generated when exposed to light can be substantially in the ratio of m to n, where m and n are natural numbers. In this case, "substantially" can be understood to mean, for example, that the ratio of the voltages actually generated in the top cell and the bottom cell differs from the ratio (m:n) by, for example, less than 25%, preferably less than 15%, and more preferably less than 5%. In this case, in each case, n top cells connected in series can be connected in parallel with m bottom cells connected in series.

[0037] In other words, the top and bottom cells are connected to each other by their voltages generated when illuminated together, i.e., preferably their voltages at the maximum power point V mpp can be configured, for example, by appropriate selection of materials and / or doping used in their fabrication, so that n top cells connected in series can generate substantially the same voltage as m bottom cells connected in series in parallel with it, when illuminated. The above-described adjustment of voltages between partial solar cells is also referred to as string voltage matching (voltage-matched string).

[0038] In this case, according to certain embodiments, it may be the case that m≧2 and n≧1. The number of current input connections and / or the number of current output connections corresponds to the larger of the two values ​​m and n (in the case of an r-configuration) or is larger than the larger of the two values ​​m and n (in the case of an s-configuration).

[0039] In other words, the number of current input and / or current output connections provided on a solar module may correlate to how the top and bottom cells are matched to each other in terms of the voltage they generate, such that in a group of multiple series-connected top cells, they may be connected in a matched manner in parallel with a group of multiple series-connected bottom cells.

[0040] According to certain embodiments, for example, the following case may occur: m=2 and n=1. In this case, except for the last 3TT solar cell, each bottom contact of a solar cell may be connected to the center tap top contact of the next adjacent 3TT solar cell, and except for the last and penultimate 3TT solar cells, each top contact of a solar cell may be connected to the center tap contact of the next subsequent 3TT solar cell.

[0041] Such matching of the voltages generated by the top and bottom cells in the ratio (2:1), together with the described interconnection of the top and bottom cells of a plurality of 3TT solar cells, may enable a particularly simple overall connection within the solar module, at the same time with high efficiency, for the prevention of losses, in particular end losses.

[0042] According to one embodiment, in each of the strings, a first bypass diode is connected in parallel with the 3TT solar cell of the string, and further, in each of the strings, a second bypass diode is connected in parallel with the top cell of the last 3TT solar cell of the string.

[0043] Like all diodes, bypass diodes can conduct substantial current exclusively in one direction, i.e., the forward direction. In solar modules, bypass diodes are typically connected anti-parallel to solar cells, for example, in a string, so that they are polarized in the opposite direction under normal operating conditions, i.e., when all solar cells are functioning properly and generating current. However, if one (or more) of the solar cells does not deliver current, for example, due to shading, the solar cell acts like an electrical load. The current generated by the other solar cells must flow across this load, which can generate significant heat and create what are known as hot spots. Furthermore, the total current flowing through a solar module generally depends on the weakest solar cell in the solar module; therefore, a single shaded solar cell can significantly limit the efficiency of the solar module. Therefore, to prevent hot spots and reduced yields, in solar modules, bypass diodes are typically connected anti-parallel to a string of solar cells interconnected in series. In this case, the cutoff voltage of the bypass diode roughly corresponds to the off-load voltage of the solar cells connected in the string.

[0044] In the solar module of 3TT solar cells described herein, as described above, the individual top and bottom cells of the plurality of 3TT solar cells can be connected in each case so that a first number of top cells are interconnected in series, a different second number of bottom cells are also connected in series, and both series circuits are connected in parallel with each other. In this case, for example, the top cell of a 3TT solar cell may not be connected in series with the top cell of the 3TT solar cell directly adjacent to it, but rather only with the top cell of the next 3TT solar cell. In this case, a first bypass diode may be connected in parallel with the 3TT solar cells of the string. However, in the above-described connection, the top cell of the last 3TT solar cell of the string is not protected by the first bypass diode. Therefore, it is advantageous to provide a respective second bypass diode for the top cell, which is connected in parallel with the top cell.

[0045] In principle, this type of second bypass diode can have different characteristics from the first, since it only has to protect a single top cell. For example, the off-load voltage of the second bypass diode can be lower than that of the first bypass diode. However, it is also possible for all bypass diodes in a solar module to be identical.

[0046] According to a particular embodiment, the first bypass diode may be electrically connected to the center tap contact of the first 3TT solar cell of the string on the one hand and to the bottom or top contact of the last 3TT solar cell of the string on the other hand, and in this case, the second bypass diode may further be electrically connected to the top or bottom contact of the last 3TT solar cell of the string on the one hand and to the center tap contact of the last 3TT solar cell of the string on the other hand.

[0047] Such a type of connection of the first and second bypass diodes may be advantageous, particularly for solar module embodiments in which the 3TT solar cells are configured in an r-type configuration and matched to each other in a ratio (2:1) in terms of voltage of their top and bottom cells, as described below with reference to certain embodiments.

[0048] According to another embodiment, the solar module may comprise at least one bypass diode connected between the strings, the bypass diode being connected on the one hand to the 3TT solar cell upstream of the last 3TT solar cell of the adjacent substring (i.e., for example, the penultimate 3TT solar cell) and on the other hand to the last solar cell of the substring to be protected.

[0049] In other words, in a solar module, the connection of the bypass diodes to the 3TT solar cells can be configured so that at least the last 3TT solar cell in one of the substrings is connected to two bypass diodes: one associated with the substring in question and connected in parallel with it, and one associated with an adjacent substring. In this case, the bypass diodes can be connected to the 3TT solar cell in question so that 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 the 3TT solar cell. In this way, it is preferable to avoid providing a separate bypass diode solely for protecting a single top or bottom cell of a single 3TT solar cell, as discussed further above with respect to the second bypass diode.

[0050] According to another embodiment, the solar module can have at least one further current input connection and / or at least one further current output connection. In this case, at least one bypass diode connected between the modules is accommodated in the solar module. In this case, the bypass diode connected between the modules can be connected on the one hand to the further current input connection 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 further current output connection.

[0051] In this embodiment of the solar module, the provision of a second bypass diode to protect the top cell of the last 3TT solar cell in the string can be omitted. Instead, this top cell can be protected by one of the first bypass diodes of the subsequent string; that is, the bypass diode connected in this way can act between strings. For this purpose, the subsequent first bypass diode contacts the last top cell of the preceding string, e.g., in an R-type configuration, it contacts the center contact of the last cell in the strand. However, if the top cell to be protected is the last 3TT solar cell not only in one of the strings in the solar module but also in the entire solar module, it may not be protected by the first bypass diode from the same solar module. Instead, this top cell is protected using the first bypass diode of an adjacent solar module. To enable the connection of bypass diodes between modules, at least one additional current input connection and / or at least one additional current output connection is provided on the solar module, through which the top cell can be connected to the first bypass diode in the adjacent solar module. An illustrative example of such an embodiment of a solar module is given below.

[0052] According to a further particular embodiment, a plurality of 3TT solar cells are arranged side by side laterally across the entire width of the solar module and electrically connected to form a substring, where the first bypass diode and, if present, the second bypass diode are each arranged laterally of the substring.

[0053] In other words, the solar module may be configured with respect to the geometric arrangement of the 3TT solar cells contained therein such that the solar cells forming a substring are arranged side by side laterally along the entire width of the solar module, and thus the substring includes a relatively large number of solar cells connected in series.

[0054] This type of connection in cell-rich substrings is particularly suitable when the individual partial solar cells each have a relatively high reverse current strength. In this case, it may be advantageous to arrange the first and second bypass diodes in each case laterally across the substring, i.e., on the outer edges of the solar module. Here, the bypass diodes are particularly easily accessible and / or can be arranged in a space-saving manner, for example, in areas of the solar module frame that locally cover the edges of the solar module.

[0055] According to an alternative specific embodiment, a plurality of 3TT solar cells are arranged side by side across the first half of the width of the solar module and electrically connected to form a first substring, and a plurality of other 3TT solar cells are arranged side by side across the second half of the width of the solar module and electrically connected to form a second substring, in which case the first substring and the second substring are connected in parallel with each other. Furthermore, a first bypass diode and, if present, a second bypass diode are spatially disposed between the first substring and the second substring, respectively.

[0056] In other words, the solar module may be configured with respect to the geometric arrangement of the solar cells arranged therein such that in each case only a relatively small number of solar cells are connected to form a substring. In this case, the solar cells connected to form a substring are geometrically arranged side by side so that they extend across only half the width of the solar module. Thus, two spatially adjacent substrings can be arranged side by side across the entire width of the solar module. In this case, the two substrings are preferably connected in parallel to each other.

[0057] For this type of connection, since the number of solar cells in a substring is relatively small, this embodiment is particularly suitable when at least some of the partial solar cells have a relatively low reverse electrical strength. In this case, it may be advantageous to geometrically position the first and second bypass diodes between the first and second substrings, respectively. Thus, the bypass diodes may be positioned, for example, in or near the geometric center of the solar module. In this case, a single first bypass diode may be provided for the two parallel-connected substrings, and this diode is connected in parallel to the two substrings. Furthermore, individual second bypass diodes may be provided for each of the two substrings, with one second bypass diode connected in anti-parallel to the top cell of the last 3TT solar cell in one of the two substrings and a further second bypass diode connected in anti-parallel to the top cell of the last 3TT solar cell in the other of the two substrings. Overall, the central placement of the bypass diodes between the substrings may achieve a favorable overall connection in the solar module, for example, with short connection distances and correspondingly low electrical resistance losses.

[0058] According to a further particular embodiment, the first bypass diode and, if present, the second bypass diode may be housed within a common diode box.

[0059] In this case, the diode box may be, for example, a housing that can accommodate the bypass diodes and protect them from, for example, environmental influences. Because both bypass diodes can be accommodated in a common diode box, the number of diode boxes required can be kept low. Furthermore, the design of the solar module relative to the diode boxes to be installed therein may be the same as or similar to the design of conventional solar modules, in which only one bypass diode is present per solar cell string. Therefore, the solar modules can be manufactured and / or installed relative to their diode boxes in the same way as conventional solar modules.

[0060] According to one embodiment, the top cell is a perovskite solar cell and the bottom cell is a silicon solar cell.

[0061] Silicon solar cells are known for their durability, reliability, and high efficiency. For example, silicon solar cells are commercially available that can provide efficiencies well above 20% and can reliably provide a useful life of 20 years or more. However, the efficiency of silicon solar cells is limited, among other things, in that silicon has a relatively small bandgap, so high-energy light can generally only be converted to electrical energy with relatively high energy losses in the form of heat generation.

[0062] In recent years, perovskite solar cells have been developed that can provide high efficiency, durability, and reliability, depending largely on the exact composition of the perovskite used. Perovskites generally have a significantly larger bandgap than, for example, silicon, and therefore solar cells formed therefrom are intended for low-loss absorption of high-energy light.

[0063] Perovskite solar cells are therefore well suited to be used as the top cell in tandem solar cells, as a partner to silicon solar cells. In this case, the exact composition of the perovskite used correlates strongly with their band gap and therefore indirectly with the off-load voltage delivered by the perovskite solar cell.

[0064] In the solar collector approach described herein, perovskite solar cells may be used as the top cell of a 3TT solar cell, and in this case, they may be optimized, for example, for their durability and reliability. In this case, the voltage of the top cell generated by lighting depends on the perovskite used. Depending on the generated voltage, the number of connections and current input and output connections within the solar module can be adjusted, as described herein, to achieve a desirable voltage match between the top and bottom cells within the solar module.

[0065] According to one embodiment, the bottom solar cell may be a rear-contact solar cell in which terminal contacts of both polarities are alternately positioned on the rear side of the bottom solar cell facing away from the top solar cell, with one of the terminal contacts of the bottom solar cell acting as a center tap contact.

[0066] Rear-contact solar cells, in which bipolar contacts are alternately arranged on the rear side of a semiconductor substrate facing away from the light, have been known for some time and are sometimes called IBC solar cells (alternate back contact). By appropriately adjusting the structure used in such rear-contact solar cells, particularly the layer thicknesses, they can be adapted to function as the bottom cell in a tandem solar cell, in which these two contacts not only function to extract the generated current from the bottom cell, but also, together with the top contact, to extract the current generated in the top cell, with one of the contacts additionally electrically connected to the top cell, for example, via a tunnel contact. In this case, the aforementioned contact functions as a center tap contact for the 3TT solar cell, but is located on the rear side of the bottom cell rather than in the spatial center between the top and bottom cells. A corresponding concept has already been proposed, for example, in [4] cited at the beginning of this specification. Because the center tap contact is provided on the rear side of the bottom cell, it is relatively easy to manufacture and can be contacted from the outside. As a result, the manufacture of 3TT solar cells and / or their connection within a solar module can be significantly simplified.

[0067] The solar module embodiments described herein can be used to form a solar collector according to the second aspect of the present invention. In this case, the characteristic that each solar module has at least two current input connections and / or two current output connections can be used to interconnect adjacent solar modules in such a way that losses, such as end-of-string losses, that occur in conventional designs and connected solar modules with 3TT solar cells are largely prevented. To this end, each of the current output connections of one of the solar modules is electrically connected to an associated one of the current input connections of an adjacent one of the solar modules. In other words, for example, a first current output of a solar module is connected to a first current input of an adjacent solar module, and a second current output of a solar module is connected to a second current input of the adjacent solar module.

[0068] As a result, as will be described in more detail below with reference to the embodiments, it is possible to prevent a situation in which at least one first 3TT solar cell closest to the current input and / or one last 3TT solar cell closest to the current output in each solar module cannot be operated optimally, thus resulting in the above-mentioned end losses. Instead, due to the special connection proposed in this specification, such end losses no longer occur in individual solar modules between adjacent solar modules via at least two output and input connections, but ideally only in the first and / or last solar module of the entire solar collector. Therefore, the impact of these end losses on the efficiency of the entire solar collector can be significantly reduced.

[0069] According to one embodiment, the current input connections of each of the solar modules are electrically isolated from each other, and the current output connections of each of the solar modules are also electrically isolated from each other, except for the current input connection of the first one of the solar modules and the current output connection of the last one of the solar modules.

[0070] Furthermore, according to one embodiment, in the case of a first one of the solar modules, at least two current input connections are electrically short-circuited or interconnected with each other, and / or in the case of a last one of the solar modules, at least two current output connections are electrically short-circuited or interconnected with each other.

[0071] In other words, each current input connection of a solar module is electrically connected to exactly one of the current output connections of an adjacent solar module, but not to the other current input connection of the same solar module or the other current output connection of an adjacent solar module. This applies to all solar modules of the solar collector, preferably except for the first and last solar modules. In the case of these two solar modules located at opposite ends of the series connection of solar modules in the solar collector, the current input connection of the first solar module and the current output connection of the last solar module serve to connect the entire solar collector to a single external electrical circuit. Thus, these two "extreme" current input and / or current output connections are electrically interconnected. Therefore, end losses cannot be avoided in the first and last solar modules, but are prevented in all solar modules between them.

[0072] It should be noted that possible advantages and configurations of embodiments of the present invention are described herein partly with reference to a solar module according to the present invention, or partly with reference to a solar collector composed of a plurality of such solar modules. Those skilled in the art will recognize that the described features can be transferred, adjusted, exchanged or modified in an appropriate manner to arrive at further embodiments of the present invention. [Brief explanation of the drawings]

[0073] Embodiments of the present invention will now be described with reference to the accompanying drawings, but neither the drawings nor the description should be construed as limiting the invention. [Figure 1(a)-(d)] The connections of a 2TT solar cell, a 4TT solar cell, a 3TT solar cell in an s-type configuration, and a 3TT solar cell in an r-type configuration are shown. [Figure 2(a)] FIG. 1 is a schematic cross-sectional view of a 3TT type solar cell with a rear contact solar cell as the bottom cell in an r-type configuration. [Figure 2(b)] FIG. 1 is a schematic cross-sectional view of a 3TT solar cell with a rear contact solar cell as the bottom cell in an s-type configuration. [Figure 3] 1 shows a conventional connection of 3TT solar cells in an r-type configuration that results in end losses. [Figure 4] 1 shows the connections in a solar module according to the invention, comprising 3TT solar cells in an r-type configuration, each having two separate current input and output connections, and a plurality of first and second bypass diodes. [Figure 5] 1 shows two solar modules connected to form a solar collector according to the present invention. [Figure 6] 1 shows the connections in a solar module according to the invention comprising 3TT solar cells in an r-type configuration with bypass diodes connected between strings, each having three separate current input and output connections to allow for the connection of bypass diodes between modules. [Figure 7] 1 shows the geometric arrangement and connection of bypass diodes in a solar module according to the invention. [Figure 8] 1 shows alternative geometric arrangements and connections of bypass diodes in a further solar module according to the invention. The drawings are merely schematic and are not to scale. It should be noted in particular that the dimensions shown in the figures are not intended to be realistic but merely to illustrate basic principles. The same reference signs in different figures indicate identical or similarly acting features. DETAILED DESCRIPTION OF THE INVENTION

[0074] DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in various embodiments and connections in Figures 1(a)-(d) as part of a respective solar module 19, multiple stacked or tandem solar cells 1 offer the possibility of achieving significantly higher efficiencies compared to solar cells with only one pn junction, due to the absorption of different spectral parts in partial cells located above and below each other to form a top cell 3 and a bottom cell 5.

[0075] As shown in FIG. 1(a), when partial solar cells 3, 5 are stacked on top of each other and connected in series to form a two-terminal tandem solar cell 7 (i.e., a cell with two connections or contacts), losses can occur due to current mismatch. This is because, on the one hand, the bandgaps of the two partial solar cells 3, 5 are usually not optimally selected due to technological boundary conditions, and one partial solar cell generates a higher current than the other. As a result, a drop in the partial cell current limits the overall current of the 2TT solar cell. On the other hand, current mismatch effects can occur even when the bandgaps are optimally selected, for example, due to changes in the illumination spectrum.

[0076] As shown in FIG. 1(b), if the individual partial solar cells 3, 5 are contacted and connected separately, losses due to current mismatch can be prevented. For this purpose, the tandem solar cell 1 is provided with four connections or contacts, i.e., two connections for each partial solar cell 3, 5 in each case, and is therefore called a four-terminal tandem solar cell 9. In this case, each partial solar cell 3, 5 can operate at its optimum operating point. However, for this purpose, all partial solar cells must be processed, contacted, and connected separately, which generally means increased costs and optical shading.

[0077] As shown in Figures 1(c) and 1(d), a tandem solar cell 1 with three terminal contacts, i.e., a 3TT solar cell 11, can significantly reduce losses due to current mismatch. In this case, Figure 1(c) shows what is known as an s-type configuration, in which the top cell 3 and bottom cell 5 are polarized in the same direction and connected in series. Figure 1(d) shows what is known as an r-type configuration, in which the top cell 3 and bottom cell 5 are polarized in opposite directions, or "reverse."

[0078] An attractive variant of the 3TT solar cell 11 is to use the bottom cell 5 as an IBC solar cell with two rear contacts arranged crosswise and one contact on the front side that allows it to contact the top cell 3. The design of such a 3TT solar cell 11 is described, for example, in the document [4] cited at the beginning of this specification.

[0079] Figures 2(a) and 2(b) show an embodiment of this type of 3TT solar cell 11, with contact placement and designation following the convention of Warren et al. (see reference [9] cited at the beginning of this specification). In this case, the same doping is reproduced in each case in the figure with the same shading. 3TT solar cells can be manufactured in different types, which can be classified as "reverse" connected, i.e., r-type configuration as shown in Figure 2(a), and "series" connected, i.e., s-type configuration as shown in Figure 2(b). Due to the simpler connection, the following mainly describes the "reverse" variant. The terminal contacts of the 3TT solar cell 11 are designated according to their characteristics. The top contact 13, or T-contact, is the single accessible contact on the top cell 3. In this case, the top contact 13 contacts the side of the top cell 3 opposite the bottom cell 5. The bottom contact 15 or R contact ("raiz" or "root") is one of the two rear contacts of the bottom cell 5, which has the opposite polarity of the bottom cell's front contact. In this case, the bottom contact 15 contacts the side of the bottom cell 5 opposite the top cell 3. The center tap contact 17 or Z side ("zusaetzlich") is a rear contact, or additional contact, with the same polarity as the front side of the bottom cell for extracting charge carriers. Therefore, the center tap contact electrically contacts the side of the bottom cell 5 opposite the side contacted by the bottom contact 15, and has the opposite polarity relative to it. Therefore, the center tap contact 17 can also extract charge carriers separated within the top cell 3 from the interface between the top cell 3 and the bottom cell 5. In this case, the center tap contact 17 may be geometrically positioned between the top cell 3 and the bottom cell 5, but in the case of a back contact, as in the case of an IBC solar cell, the center tap contact 17 may alternatively be geometrically positioned on the back surface of the bottom cell 5, i.e., laterally adjacent to the bottom contact 15, in which case it serves as an electrical connection to the interface between the top cell 3 and the bottom cell 5.

[0080] 2(a) and 2(b) further show the voltages developed between the various terminal contacts 13, 15, 17. In this case, V top is the voltage generated by the top cell 3, and V bot is the voltage generated by the bottom cell 5. V RT is the voltage generated between the bottom contact 15 and the top contact 13, and V ZT is the voltage developed between the center tap contact 17 and the top contact 13, and V RZ is the voltage developed between the bottom contact 15 and the center tap contact 17.

[0081] Among other advantages, the 3TT solar cell is: (i) The resulting solar module can be operated as a bifacial tandem module in the free field, since the top and bottom solar cells do not need to have the same current. Therefore, a significant market entry hurdle is avoided, since the additional yield of the tandem module must be measured not only against a monofacial silicon module, but also against a bifacial silicon module. These modules have an additional yield of approximately 5% to 20% compared to a monofacial PV module of the same efficiency, depending on the mode and location of use; (ii) Low losses are possible in the case of a non-optimally adjusted bandgap or voltage at the maximum power point. As a result, the top cell 3 can be selected with respect to other criteria, such as the reliability or efficiency of the top cell; (iii) For each additional solar cell in a string of solar cells, the voltage increases only by the voltage of the bottom cell, not by the combined voltage of the bottom and top cells. This allows for more photovoltaic modules per module strand and therefore fewer cables required in the system design.

[0082] As shown in partial views in Figures 1(c) and 1(d), 3TT solar cells 11 may be integrated into a solar module 19 by a combination of series and parallel connections. Since the top cell 3 generates a significantly higher voltage than the bottom cell 5, for example, a single top cell 3 is connected in parallel with two bottom cells 5. For this purpose, the top contact 13, i.e., the contact of the top cell 3 opposite the bottom cell 5, is led to a contact of opposite polarity on every other 3TT solar cell 11, which is the center tap contact 17.

[0083] Because there is no next 3TT solar cell 11 at the end of the string, losses occur here on the order of magnitude of the power of one to two 3TT solar cells, depending on the cell design or configuration and / or connection method. Losses at the end of the string have been theoretically studied, for example, in [5] cited at the beginning of this specification, and considerations regarding voltage adjustment through cell connection have been discussed since the introduction of 3TT solar cells, for example, in [2] cited at the beginning of this specification. Possible connection techniques for 3TT tandem PV modules are described in

[10] . Thus, practical solutions exist for connecting 3TT solar cells in solar modules. In this case, instead of connecting the 3TT solar cells through a common connector structure, as described in

[10] , in which the various terminal contacts of the 3TT solar cells may then be connected or wired using different methods, a serial connector may alternatively be used, by which adjacent solar cells are typically contacted and connected within the module, typically with one single connector leading from the front side of the 3TT solar cell to the rear side of the adjacent 3TT solar cell.

[0084] 3 shows possible conventional connections of 3TT solar cells 11 in a combination of series and parallel connections for module integration. In either case, there are two wiring ends 23 at either end of the string 21. These are conventionally interconnected by electrical connectors 25 so that the current generated by the string 21 can be extracted from the solar module 19 at a current input connection 27 and a current output connection 29. In other words, the connectors 25 at each string end ensure that the current generated within the string 21 can be extracted from the string 21.

[0085] However, the bottom cell 5' (the leftmost cell in FIG. 3 ) of the first 3TT solar cell 11' of the string 21 is short-circuited by the connector 25, and its power is not extracted. Furthermore, at each end of the string, i.e., the first 3TT solar cell 11' and the last 3TT solar cell 11'', the top cells 3', 3'' operate at only about 50% of their voltage. This leads to a loss, also called end-of-string loss, which in the illustrated case is equivalent to the power of about one 3TT solar cell. Furthermore, by connecting the wiring terminals 23 using the connector 25, a common bypass diode 31 can be connected in parallel with all 3TT solar cells 11 of the string 21, including all top cells 3 and all bottom cells 5. This means that end-of-string loss occurs when integrating each bypass diode. For a currently common string length of 20 cells, this procedure results in a power loss of about 5%, which often more than compensates for the advantages of 3TT solar cells compared to, for example, 2TT solar cells. For perovskite solar cells, even a small string length per bypass diode is often possible, and therefore the impact of end losses is even greater.

[0086] The approaches discussed in this patent application discuss both ways to transfer end-of-string losses from the module level (typically with about 60 cells) or substring level (typically a 1 / 3 module with about 20 cells) to the system level, for example, of a solar collector (typically with up to 2000 cells), in order to minimize their relative contribution, and also highlight advantageous options for the integration of bypass diodes.

[0087] In particular, embodiments of the present invention address the following aspects: (i) Electrical connections between solar modules to form, for example, one cable with two cores or a solar collector with two cables; (ii) integration of bypass diodes at the ends of the strings, eliminating the need for contacts or wiring ends together; (iii) Modular designs for modules in the middle and at the ends of a string with external combination of contacts (eg, module contacts that are combined outside the module), eg, with appropriate plugs or connectors.

[0088] 4 shows an embodiment of a solar module 19 according to the invention, in which the 3TT solar cells 11 are wired together in a special way and to two current input connections 27', 27" and two current output connections 29', 29'. In this case, moreover, at least one first bypass diode 33 and one second bypass diode 35 are provided for each of the two substrings 21', 21" shown by way of example.

[0089] 5 shows how two solar modules 19 according to the invention can be connected to form a solar collector 37 according to the invention. It should be noted that in this case, an actual solar collector will of course typically comprise three or more solar modules 19, but the wiring principles can be clearly discerned on the basis of this simplified example.

[0090] With regard to the above aspect (i), Figures 4 and 5 show that all string ends at different potentials are brought to terminal contacts in the form of two current input connections 27 and current output connections 29 in each case. As a result, substrings 21', 21'' of several adjacent solar modules 19 are connected beyond the physical limits of the solar module 1 to form an overall string. The interconnection of the solar modules 19 via the two current input connections 27 and current output connections 29 in each case makes it possible to provide all of the top cells 3 in the entire string (except the top cell 3 of the very last 3TT solar cell 11) with every other bottom cell 5 for parallel connection in each case, and to extend the connection concept beyond the module limits. As a result, the end-of-string losses occurring in each of the substrings 21', 21'' in parallel with the bypass diodes 31 (i.e., in each case, typically for 20 cells or less) are shifted to the system level with multiple interconnected solar modules 1 (typically with 2000 cells or more), which reduces the relative contribution of the end-of-string losses by two orders of magnitude (i.e., from 1 / 20 = 5% to 1 / 2000 = 0.05%).

[0091] With regard to embodiment (ii) above, Figures 4 and 5 schematically illustrate the integration of a first bypass diode 33 and a second bypass diode 35. The first bypass diode 33 (shown extending to the bottom of the figure) protects each substring 21', 21'', as in current 2TT solar cell or single-junction solar cell solar modules. However, in this case, the last top cell 3'' of each substring 21', 21'' is not protected and is therefore protected by a separate second diode 35.

[0092] At the end of the entire string extending over a plurality of solar modules 19, for the above-mentioned connection, the entire string end 43 must be brought together for connection to power electronics or an inverter, typically to allow the generated current to be dissipated from the three parallel strings. In this case, the first strand comprises in each case the next top cell 3 of the first plurality connected in series, the second strand comprises in each case the next other top cell 3 of the second plurality connected in series, and the third strand comprises in each case the next bottom cell of the plurality connected in series.

[0093] In the examples shown in Figures 3 to 5, the voltage V generated by the top cell 3 when illuminated top is the voltage of bottom cell 5, V bot When the ratio is approximately twice as large as V, top / V bot is an integer ratio (m:n), specifically (2:1). Thus, the connection described in each case includes n=1 top cells 3 connected in series, connected in parallel with m=2 bottom cells 5 connected in series. In this case, m=2 parallel strands of series-connected top cells 3 are provided.

[0094] Generally, the voltage ratio of the top cell and the bottom cell is an integer ratio m:n, e.g., V top / V bot Note that the numbers m:n may be matched (i.e., "matched") to one another in other ways, where m:n=3:2 (not shown).

[0095] FIG. 6 shows an alternative embodiment of a solar module 1 that differs from the one in FIGS. 4 and 5, in particular with regard to the provision and connection of bypass diodes and with regard to the way in which this solar module 1 is connected to adjacent modules.

[0096] In particular, the solar module 1 comprises, in the center of the solar module 19, an inter-string connected bypass diode 34. The bypass diode is connected, on the one hand, to the penultimate 3TT solar cell 11''' upstream of the last 3TT solar cell 11'' of the previous 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 inter-string connected bypass diode 34 is connected, on the one hand, to the bottom contact 15 of the penultimate 3TT solar cell 11''' of the previous adjacent substring 21'', and, on the other hand, to the bottom contact 15 of the last solar cell 11'' of the substring 21' to be protected. In this way, the last solar cell 11'' in the previous adjacent substring 21'' is connected both to the bypass diode 36 associated with that substring 21'' and to the inter-string bypass diode 34 associated with the adjacent substring 21'. As a result, its top cell 3''' is also protected, so that the second bypass diode 35 as proposed for the embodiment of FIG. 4 can be omitted.

[0097] Furthermore, the solar cell module 1 comprises, in addition to the first and second current input connections 27', 27'', a further current input connection 27''' and / or, in addition to the first and second current output connections 29', 29'', a further current output connection 29'''. Furthermore, the solar module 1 comprises at least one bypass diode 36 connected in such a way that it can protect both the 3TT solar cells 11 of the solar module 1 in question and at least one 3TT solar cell 11 of an adjacent solar module. Therefore, the bypass diode is also referred to in this document as an inter-module bypass diode 36.

[0098] In the example shown, the bypass diodes 36 connected between the modules are in electrical contact with the further current input connection 27''', on the one hand, and with the bottom contact 15 of one of the 3TT solar cells 11 in the solar module 1, on the other hand. Furthermore, in addition to the bypass diodes 36 connected between the modules, the entire solar module also comprises a further bypass diode connected as described above as an inter-string bypass diode 34. In this case, the bypass diode 34 is connected between the center tap contact 17 of the 3TT solar cell 11'' of the substring 21'' shown on the left in the figure and the bottom contact 15'' of the last 3TT solar cell 11'' of the substring 21' shown on the left in the example, whose bottom contact 15 is contacted by the inter-module bypass diode 36. However, since the top cell 3'' of the last 3TT solar cell 11'' is not protected thereby, the center tap contact 17'' of said last 3TT solar cell 11'' is connected to a further current output connection 29'''.

[0099] Here, since in each case between adjacent solar modules 1 their further current input connection 27''' is in each case connected to the further current output connection 29''' of the adjacent solar module 1, the bypass diode 36 connected between the modules can also protect the top cell 3'' of the last 3TT solar cell 11'' of the adjacent solar module 1. Therefore, in this embodiment it is possible to omit providing one or more second bypass diodes 35.

[0100] 7 and 8 show possible geometric arrangements of bypass diodes 33, 35 in each substring 21 of a 3TT solar module 19 for 3TT solar cells 11 with high electrical strength (FIG. 7) and low electrical strength (FIG. 8).

[0101] 7, a plurality of 3TT solar cells 11 are arranged side by side in the horizontal direction across the entire width B of the solar module 19, and in the example shown, two such rows are electrically connected to form a substring 21'. In this case, the first bypass diode 33 and the second bypass diode 35 are arranged side by side in the horizontal direction of the substring 21'. In this case, for example, the bypass diodes 33, 35 may be arranged near the side edges of the solar module 19, for example, in a frame (not shown) that surrounds the solar module 19, or underneath.

[0102] In the figure, squares represent 3TT solar cells 11. Lines 39 along the edges of the 3TT solar cells 11 indicate three-pole connections between the solar cells. A practical solution for this three-pole connection is described in

[10] . Vertically hatched dots symbolize bottom contacts 15 (R contacts) to the bottom cells 5, horizontally hatched dots represent top contacts 13 (T contacts) to the top cells 3, and diagonally hatched dots represent center tap contacts 17 (Z contacts) of the 3TT solar cells 11. To keep the contact pattern for the bypass diodes 33 and 35 simple, only the contacts to the geometrically closest 3TT solar cells 11 are shown in each case. Terminal contacts are routed to further 3TT solar cells 11 in the string 21 by connections between the 3TT solar cells 11 (represented by lines 39). This arrangement includes two parallel rows of solar cells connected in series. This geometry is suitable for solar cells with high reverse electrical strength.

[0103] In contrast, in the embodiment shown in FIG. 8 , a plurality of 3TT solar cells 11 are arranged side by side laterally across the first half B / 2 of the width B of the solar module 19 and are electrically connected to form a first substring 21′, and a plurality of other 3TT solar cells are arranged side by side laterally across the second half of the width of the solar module 19 and are electrically connected to form a second substring 21″. In this case, the first substring 21′ and the second substring 21″ are connected in parallel. A first bypass diode 33 and a second bypass diode 35 are arranged side by side laterally between the first substring 21′ and the second substring 21″, respectively. Such a type of connection is particularly suitable for 3TT solar cells 11 with low reverse electrical strength.

[0104] That is, as in the case of half-cell modules, a bypass connection for the 3TT solar cells 11 with low reverse electrical strength can be provided in the center of the module (Fig. 8). However, the 3TT solar cells 11 are connected quasi-series in a double string (indicated by the peripheral line 39). The derived contacts may be further connected to the next substring 21 or the next solar module 19. The center contact 17 (Z contact) is tapped by the 3TT solar cell 11 that is not located directly in the center of the module. The contact is established via a wired connection, which is, as standard, routed to the next top cell 3 for further connection. This connection can be used as a current tap.

[0105] A particular feature of the geometric arrangement of the solar cells 11 and bypass diodes 33, 35 in Figure 7 is that in each case, two of the bypass diodes 33, 35 located laterally of the double string 21 can be combined into a common diode box 41 (shown in dashed lines in Figure 7 for a better overview). Thus, for example, it is possible to configure a solar module 19 with three conventional diode boxes 41. Similarly, in the geometric arrangement of the solar cells 11 and bypass diodes 33, 35 in Figure 8, the two bypass diodes 33, 35 can be connected in one diode box (not shown in Figure 8 for a better overview), thus re-implementing the diode connection with the three conventional diode boxes 41 in the center of the module.

[0106] When the proposed solar modules 19 are connected, it is optionally possible to accept string end losses and 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-core connection between the solar modules 19. In this case, the solar modules 19 are wired in series, with the negative contact in each case connected to the positive contact of an adjacent solar module 19. If it is desired to utilize the entire potential of the connection, the first current output connection 29' must be connected in series to the first current input connection 27' and the second current output connection 29" must be connected to the second current input connection 27" of the adjacent solar module 19 via a two-core connection, i.e., for example, using a two-core cable or using two cables.

[0107] It should be noted that terms such as "comprising" and "having" 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-mentioned embodiments may be used in combination with other features or steps of other of the above-mentioned embodiments. Reference signs in the claims should not be considered as limiting.

[0108] Reference Code List 1 tandem solar cell 3 Top Cell 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 cells 9 4TT solar cells 11 3TT solar cells 11' First 3TT solar cell 11'' Last 3TT Solar Cell 13 Top Contact 15 Bottom Contact 17 Center Tap Contact 19 Solar Modules 21 strings 21' Substring 21'' substring 23 Wiring end 25 connectors 27 Current Input Connection 27' First power input connection 27'' Secondary Power Input Connection 27'' additional power input connection 29 Current output connection 29' First current output connection 29'' Second Current Output Connection 29'' Additional current output connections 31 Common bypass diode 33 First bypass diode 34 Bypass diodes connected between strings 35 Second bypass diode 36 Bypass diodes connected between modules 37 Solar Collector 39 Series connection line 41 Diode Box 43 Entire string end

Claims

1. A solar module (19), a plurality of 3TT solar cells (11) interconnected to form at least one string (21); and at least two current input connections (27) at the current input of the solar module (19) and / or at least two current output connections (29) at the current output of the solar module (19), Each 3TT solar cell (11) has a stack comprising a top cell (3) and a bottom cell (5) disposed thereunder, the top cell (3) and the bottom cell (5) differing from each other in terms of the voltages they generate when exposed to light; Each 3TT solar cell (11) has three terminal contacts: a top contact (13) in electrical contact with the side of the top cell (3) opposite the bottom cell (5), a bottom contact (15) in electrical contact with the side of the bottom cell (5) opposite the top cell (3), and a center tap contact (17) in electrical contact with the 3TT solar cell at the interface between the top cell (3) and the bottom cell (5); a first one (27') of the current input connections (27) is connected to at least one of the terminal contacts of a first one (11') of the 3TT solar cells (11) closest to the current input, and a second one (27'') of the current input connections (27) is connected to at least one of the terminal contacts of a second one of the 3TT solar cells (11) adjacent to the first 3TT solar cell (11'); and / or A solar module (19) in which a first one (29') of the current output connections (29) is connected to at least one of the terminal contacts of the last one (11'') of the 3TT solar cells (11) closest to the current output, and a second one (29'') of the current output connections (29) is connected to at least one of the terminal contacts of the penultimate one of the 3TT solar cells (11) adjacent to the last 3TT solar cell (11').

2. 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 opposite polarity; the first current input connection (27') is connected to the center tap contact (17) of the first 3TT solar cell (11') and the second current input connection (27'') is connected to the center tap contact (17) of the second solar cell (11); and / or 2. The solar module of claim 1, wherein the first current output connection (29') is connected to the top contact (3) of the last 3TT solar cell (11'') and the second current output connection (29'') is connected to the top contact (3) of the penultimate 3TT solar cell (11).

3. the voltage of the top cell (3) generated when exposed to light and the voltage of the bottom cell (5) generated when exposed to light are substantially in the ratio m to n, where m and n are natural numbers; 10. A solar module according to any one of the preceding claims, in which in each case n top cells (3) connected in series are connected in parallel with m bottom cells (5) connected in series.

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

5. m=2 and n=1, Except for the last 3TT solar cell (11''), each bottom contact (15) of the 3TT solar cells (11) is connected to the center tap contact (17) of the next adjacent 3TT solar cell (11); 5. The solar module according to claim 3, wherein, except for the last 3TT solar cell 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 succeeding 3TT solar cell (11).

6. 10. The solar module of claim 9, wherein in each of the strings (21), a first bypass diode (33) is connected in parallel with the 3TT solar cell (11) of the string (21), and further, in each of the strings (21), a second bypass diode (35) is connected in parallel with the top cell (3) and / or the bottom cell (5) of the last 3TT solar cell (11') of the string (21).

7. the first bypass diode (33) is electrically connected to the center tap contact (17) of the first 3TT solar cell (11') of the string (21) on the one hand, and to the bottom contact (15) or top contact (13) of the last 3TT solar cell (11'') of the string (21) on the other hand; 7. The solar module of claim 6, wherein the second bypass diode (35) is electrically connected to the top contact (13) or the bottom contact (15) of the last 3TT solar cell (11'') of the string (21) on the one hand, and to the center tap contact (17) of the last 3TT solar cell (11'') of the string (21) on the other hand.

8. The solar module (19) has at least one bypass diode (34) connected between the strings; 10. A solar module according to any one of the preceding claims, wherein the bypass diodes (34) connected between strings are connected on the one hand to a 3TT solar cell (11''') upstream 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 protected.

9. the solar module (19) has at least one further current input connection (27''') and / or at least one further current output connection (29''', At least one bypass diode (36) connected between modules is housed within said solar module (19); the bypass diode (36) connected between 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 the bottom contact (15), of one of the 3TT solar cells (11) in the solar module (19); and / or 10. A solar module according to any one of the preceding claims, wherein the centre tap contact (17) of the last 3TT solar cell (11) of the solar module (19) is connected to the further current output connection (29''').

10. A plurality of 3TT solar cells (11) are arranged side by side across the entire width (B) of the solar module (19) and are electrically connected to form substrings (21'); 10. The solar module according to any one of claims 6 to 9, wherein the first bypass diodes (33) and, optionally, the second bypass diodes (35) are respectively arranged laterally in the substring (21').

11. A plurality of 3TT solar cells (11) are arranged side by side across the first half of the width (B) of the solar module (19) and are electrically connected to form a first substring (21'); a plurality of 3TT solar cells (11) are arranged side by side across the second half of the width of the solar module (19) and are electrically connected to form a second substring (21''); the first substring (21') and the second substring (21'') are connected in parallel with each other; 10. A solar module according to claim 6, wherein the first bypass diode (33) and, optionally, the second bypass diode (35) are respectively arranged between the first substring (21') and the second substring (21'').

12. Solar module according to any one of claims 6 to 11, wherein the first and second bypass diodes (33, 35) are housed in a common diode box (41).

13. 10. The solar module according to any 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.

14. 10. The solar module of claim 9, wherein the bottom solar cell (5) is a rear-contact solar cell in which terminal contacts (15, 17) of opposite polarity are alternately arranged on the rear side of the bottom solar cell (5) opposite the top solar cell (3), and one of the terminal contacts of the bottom solar cell (5) functions as the center tap contact (17).

15. A solar collector comprising a plurality of solar modules (19) according to any of the preceding claims, A solar collector, in each case for adjacent solar modules (19), wherein each of the current output connections (29) of one of the solar modules (19) is electrically connected to an associated one of the current input connections (27) of the adjacent one of the solar modules (19).

16. 16. A solar collector according to claim 15, wherein, with the exception of the current input connection (27) of a first one of the solar modules (19) and the current output connection (29) of the last one of the solar modules (19), the current input connections (27) of each of the solar modules (19) are electrically insulated from each other and the current output connections (29) of each of the solar modules (19) are electrically insulated from each other.

17. 17. A solar collector according to claim 15, wherein in the case of a first one of the solar modules (19), the at least two current input connections (27) are electrically short-circuited or interconnected with each other, and / or in the case of a last one of the solar modules (19), the at least two current output connections (29) are electrically short-circuited or interconnected with each other.

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