Solar module comprising three-terminal stacked solar cells

Abstract

A solar module (19) and a 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); and at least two current input connections (27) at the solar module current input and / or at least two current output connections (29) at the solar module current output. Each 3TT solar cell has a stack with a top cell (3) and a bottom cell (5) arranged thereunder. Each 3TT solar cell comprises, as terminal contacts, a top contact (13), a bottom contact (15) and a center tap contact (17). A first current input connection (27 ') of the current input connections (27) is connected to at least one terminal contact of a first 3TT solar cell (11') closest to the current input, and a second current input connection (27 '') of the current input connections (27) is connected to at least one terminal contact of a second 3TT solar cell adjacent to the first 3TT solar cell, and / or a first current output connection (29 '') of the current output connections is connected to at least one terminal contact of the last 3TT solar cell (11'') closest to the current output, and a second current output connection (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 wiring described in particular greatly prevents string end loss and also allows for advantageous integration of bypass diodes (33, 35).

Description

Field of the Invention

[0001] The present invention relates to a solar module comprising a tandem solar cell. Background Art

[0002] Solar modules are used to convert light, especially solar radiation, into electrical energy. Such solar modules are also referred to as photovoltaic modules or PV modules. In this case, the solar module comprises a plurality of solar cells interconnected in series and / or in parallel. The solar module typically further comprises a current input connection and a current output connection so that the solar module can be connected in series and / or in parallel to other solar modules to form a solar collector and ultimately be able to supply the electrical energy generated in the solar module to an external circuit to which a load is connected.

[0003] Traditionally, solar modules typically use solar cells in which charge carrier pairs generated by absorption of incident light are separated under a single potential difference, for example generated by a p-n junction. In this case, the power or efficiency of the solar cell depends especially on the potential difference and thus on the (semiconductor) material used to generate the potential difference. In this case, the efficiency of the solar cell is especially limited by the fact that, depending on the bandgap of the semiconductor material used, the low-energy part of the radiation light may not be absorbed, while the high-energy part may only be converted into electrical energy with a significant energy loss.

[0004] 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 each other. Such solar cells are referred to as tandem solar cells and sometimes also as multi-solar cells or stacked solar cells. In this case, the materials of the two partial solar cells are different and thus their bandgaps are also different. In this case, the partial solar cell facing the incident light, also referred to as the top cell, typically has a larger bandgap and is thus configured to absorb and convert the high-energy part of the incident light with a relatively low energy loss. The other partial solar cell arranged below it, also referred to as the bottom cell, has a smaller bandgap and is thus configured to absorb and convert the low-energy part of the incident light with a relatively low loss.

[0005] The tandem solar cell is preferably configured as a monolithic one. That is to say, the tandem solar cell is designed as a single component, in which all components, such as various semiconductor layers and contacts, are rigidly interconnected. For this purpose, for example, a plurality of layers can be deposited on the entire surface and / or partial regions one on top of the other. In this case, the tandem solar cell includes at least two terminal contacts, but as described below, in some embodiments, it also includes three, four or more terminal contacts. In this case, the terminal contacts are understood as electrical contacts on the tandem solar cell, which can be reached from the outside, and the solar cell or its partial solar cells can be electrically connected to other solar cells or their partial solar cells through these electrical contacts.

[0006] In this case, various connection configurations of the tandem solar cell are known.

[0007] The known two-terminal tandem solar cell, also called a 2TT solar cell, includes only two terminal contacts, where typically a so-called top contact is provided on the front side of the tandem solar cell and a so-called bottom contact is provided on the back side. Such a 2TT solar cell can be easily connected to a solar module, i.e., basically in the same way as a conventional non-tandem solar cell. However, the total current flowing through the 2TT solar cell must be of the same magnitude for the two partial solar cells, which means that the current is limited by the weaker one of the two partial solar cells. Accordingly, losses due to current mismatch often occur. The reason for this may be, on the one hand, that due to the influence of technical boundary conditions, the bandgaps of the two partial solar cells are not selected optimally, and one partial solar cell generates a higher current than the other partial solar cell, and the lower current of the weaker partial solar cell thus limits the total current of the tandem solar cell. On the other hand, due to the change of the radiation spectrum, even when the bandgaps are optimally selected, a current mismatch effect may also occur.

[0008] If the individual partial solar cells of the tandem solar cell can be separately contacted and connected, losses due to current mismatch can be largely prevented. For this purpose, the tandem solar cell can include four terminal contacts, i.e., configured as a so-called 4TT solar cell. In this case, each individual partial solar cell has its own two terminal contacts, and thus can operate independently of the other partial solar cell at its optimal operating point. However, for this purpose, all partial solar cells must be separately processed, contacted and connected, which may require increased expenditure and result in increased light shielding.

[0009] As a quasi-intermediate path between 2TT and 4TT solar cells, a tandem solar cell including three terminal contacts has been developed and is thus referred to as a 3TT solar cell. In addition to the top and bottom contacts, the 3TT solar cell also includes an additional terminal contact, which is referred to as the center tap contact. The center tap contact 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. Thus, on the one hand, the 3TT solar cell allows for electrical connection within a solar module, in which case losses due to current mismatch may be significantly reduced. On the other hand, compared to the case of 4TT solar cells, connecting 3TT solar cells within a module may be less complex, and / or the light shading losses due to the terminal contacts may be less than those of 4TT solar cells.

[0010] For a long time, theoretical and experimental studies have been conducted on 3TT solar cells and solar modules constructed therewith. Considerations and findings regarding their internal structure and their arrangement and connection within solar modules are particularly contained in the documents listed below, some of which are cited hereinafter:

[0011] [1] Sakai, S. and Umeno, M., "Theoretical Analysis of a Novel Wavelength Division Solar Cell", Journal of Applied Physics, Vol. 51, No. 9, pp. 5018 - 5024, 1980.

[0012] [2] Gee, J.M., "Comparison of Different Module Configurations for Multibandgap Solar Cells", Solar Cells, Vol. 24, Nos. 1 - 2, pp. 147 - 155, 1988.

[0013] [3] Jimeno, J.C., Gutierrez, R., Fano, V., Habib, A., del C., Rasool, M.A. and Otaegi, A., "A Three - Terminal Parallel Silicon Tandem Solar Cell", Energy Procedia, Vol. 92, pp. 644 - 651, 2016.

[0014] [4] Nagashima, T., Okumura, K., Murata, K. and Kimura, Y., "Three - Terminal Tandem Solar Cell with a Back - Contact - Type Bottom Cell", 2000. Proceedings of the 28th IEEE PVSC, 1193 - 96.

[0015] http: / / ieeexplore.ieee.org / servlet / opac?punumber=7320.

[0016] [5] McMahon, William; Schulte-Huxel, Henning; Buencuerpo, Jeronimo; Geisz, John; Young, Michelle; Klein, Talysa et al. (2021): Uniform voltage-matched strings using triple-junction tandem solar cells: Principles and end losses. See: IEEE J. Photovoltaics 11(4), pp. 1078-1086. DOI: 10.109 / jphoto.2021.3068325.

[0017] [6] Jimeno Cuesta, J., Luque Lopez, A., Recart F., LagoAurrekoetxea, R., Gutierrez Serrano, R., Varner, K., Ikaran Salegi, C. et al. “Photovoltaic device and photovoltaic panel”, WO / 2011 / 045462, filed on Oct. 14, 2010, published on Apr. 21, 2011.

[0018] [7] Borden, P.G. “Three-terminal solar cell circuit”, US4513168 A, filed on Apr. 19, 1984, published on Apr. 23, 1985.

[0019] [8] H. Uzu, G. Koizumi, “Solar cell module”, WO / 202 / 196288, Mar. 19, 2020, published on Oct. 1, 2020.

[0020] [9] E.L. Warren et al., “Classification of triple-junction tandem solar cells”, ACS Energy Letters, Apr. 2020, Vol. 5, No. 4, pp. 1233-1242

[0021]

[10] M. Zehender et al., “Module interconnection of three-terminal heterojunction bipolar transistor solar cells”, AIP Conference Proceedings 2012040013 (2018); https: / / doi.org / 10.1063 / 1.5053521, online published: Sep. 13, 2018

[0022]

[11] H. Schulte-Huxel et al., “Cascade modeling of silicon-based two-terminal, three-terminal, and four-terminal tandem modules”, Journal of Photovoltaics, IEEE, Vol. 8, No. 5, Sep. 2018, pp. 1370-1375

[0023]

[12] R. Witteck et al., "Partial shading of one solar cell in a photovoltaic module with three-terminal cell interconnection", Solar Energy Materials and Solar Cells 219 (2021) 110811

[0024] It has been observed that in the case of a solar module constructed with 3TT solar cells, the efficiency or power generation may not be optimal, i.e., may in particular be lower than the efficiency expected based on the efficiency of the individual solar cells and the number of solar cells in the solar module. SUMMARY OF THE INVENTION

[0025] Accordingly, there may be a need for solar modules that allow for higher efficiency or power generation. In particular, there may be a need for solar modules based on 3TT solar cells, in which the high efficiency of the individual solar cells results in a high efficiency of the entire solar module due to an appropriate selection of the configuration of the solar cells within the solar module. In addition, there may be a need for an efficient solar collector including such a solar module.

[0026] The above need can be met at least in part by the subject matter of any one of the independent claims of the present application. Advantageous embodiments are specified in the dependent claims and in the following description and drawings.

[0027] According to a first aspect of the invention, a solar cell module is described that includes a plurality of 3TT solar cells and at least two current input connections located at the current input end of the module and / or at least two current output connections located at the current output end 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 with a top cell and a bottom cell arranged therebelow, the top cell and the bottom cell being different from each other in terms of the voltage generated when exposed to light. Each 3TT solar cell has three terminal contacts, a top contact in electrical contact with the side of the top cell facing away from the bottom cell, a bottom contact in electrical contact with the side of the bottom cell facing away from the top cell, and a center tap contact in electrical contact with the 3TT solar cell at the interface between the top cell and the bottom cell. The first current input connection among the current input connections is connected to at least one terminal contact of a first 3TT solar cell among the 3TT solar cells closest to the current input end, and the second current input connection among the current input connections is connected to at least one terminal contact of a second 3TT solar cell adjacent to the first 3TT solar cell among the 3TT solar cells. In addition, the first current output connection among the current output connections is connected to at least one terminal contact of the last 3TT solar cell among the 3TT solar cells closest to the current output end, and the second current output connection among 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 among the 3TT solar cells.

[0028] According to a second aspect of the present invention, a solar collector is described which comprises a plurality of solar modules according to an embodiment of the first aspect of the present invention, and in the case of being adjacent to the solar modules, in each case, each current output connection of one of the solar modules is electrically connected to the associated current input connection of the adjacent solar module in the solar modules.

[0029] As an introduction, the basic concepts described herein regarding the embodiments of the invention will be briefly explained here, and this explanation is intended to be construed as merely a general overview and not a limitation of the invention:

[0030] The present invention particularly describes a solar module in which, due to the special type of arrangement and connection of the 3TT solar cells accommodated therein, losses that occur in conventional solar modules in which 3TT solar cells are arranged and connected in a conventional manner can be largely prevented, especially the known series-end losses. As will be explained in more detail below, in this case, the main feature of the solar module described herein can be considered to be the fact that, unlike in the case of conventional solar modules, which typically only include a single current input connection and a single current output connection, in each case it includes two or more such current input connections as well as current output connections, and in this case, these connections are connected to the 3TT solar cells within the solar module in a specific manner. Due to the special type of connection and the multiple current input connections and current output connections, in this case it is possible that the series-end losses caused by some of the solar cells - these series-end losses do not contribute to the efficiency of the module or do not contribute optimally to the efficiency of the module according to the connection - are no longer generated at least once on each connected string of solar cells, i.e., in each solar module. Instead, a plurality of solar modules can be interconnected such that the corresponding end losses are only generated once in the entire plurality of solar components, thereby significantly reducing the impact on the overall efficiency of the solar collector. In addition, an embodiment of a solar module including 3TT solar cells is described, in which the proper connection of the bypass diodes ensures the reliable operation of the solar module while preventing the above-mentioned end losses.

[0031] The possible implementations and advantages of the embodiments of the solar module and the method for producing the module will be described in more detail below:

[0032] The solar cell module described herein includes a plurality of solar cells in the form of 3TT solar cells. For example, a solar module typically includes more than ten solar cells, usually more than 50 solar cells, but generally less than 300 solar cells, often less than 150 solar cells. Each individual solar cell is a two-dimensionally formed diode with a surface area generally ranging from 10 square centimeters to 1000 square centimeters, typically from 100 square centimeters to 500 square centimeters. The thickness of the solar cell is usually from 10 micrometers to 1000 micrometers, typically from 50 micrometers to 400 micrometers. At least a part of the solar cell can be formed based on a crystal, i.e., a single crystal, polycrystalline, or polycrystalline semiconductor substrate such as a silicon wafer. Alternatively or additionally, a part of the solar cell can be formed with an amorphous semiconductor material, for example, in the form of one or more thin films.

[0033] The solar cells are connected to form one or more strings. In this case, the entire solar cells or partial solar cells forming the solar cells can be interconnected in series and / or in parallel. In this case, a string is understood as the smallest unit of a plurality of interconnected solar cells, and the entire solar module can include a plurality of such strings interconnected in series and / or in parallel. In this case, the number of solar cells that can be combined into a string may depend on various influencing factors. This number is usually selected, in particular, such that the voltage generated by the string during illumination does not exceed the reverse withstand voltage of each individual solar cell in the string. Usually, such a string includes 3 to 50 solar cells connected in series, usually 6 to 30 solar cells connected in series.

[0034] The 3TT solar cells installed in the solar module consist of a first partial solar cell and a second partial solar cell. The first partial solar cell is arranged on the side of the solar cell facing the incident light during use, and this side is called the top side, and thus the first partial solar cell is called the top cell. The second partial solar cell is arranged below the first partial solar cell and is thus called the bottom cell. Each partial solar cell can successively have a single p-n junction, or when using a special cell design, can have multiple p-n junctions, which are preferably arranged in series with each other along the direction of the incident light.

[0035] The top cell and the bottom cell differ in the semiconductor material 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 amounts of the two bandgaps can differ from each other by more than 20%, preferably by more than 40%, and even by more than 80%. Due to the different bandgaps, in each case, by appropriate local doping, different voltages are established under the potential differences (e.g., due to the corresponding p-n junctions) formed in the two partial solar cells upon irradiation. In other words, there are significant differences in the open-circuit voltages (which are sometimes also referred to as the open-circuit voltage V OC ) between the top cell and the bottom cell. For example, the V OC of the top cell can be 30% or more, 50% or more, or even 100% or more larger than the V OC of the bottom cell.

[0036] Each 3TT solar cell includes exactly three terminal contacts through which it is connected to other 3TT solar cells. In this case, the terminal contacts are typically formed by a conductive layer, such as a metal layer, attached to or integrated into the solar cell. In this case, the terminal contacts can be formed by a single layer, but the terminal contacts can also consist of multiple partial regions or partial layers.

[0037] The three terminal contact portions can be represented according to the convention introduced by Warren et al. (see reference [9] in the list of references cited in the description introduction). In this case, the first contact portion is typically arranged on the front side surface of the solar cell facing the incident light and electrically contacts the side of the top cell facing away from the bottom cell ("electrically contacts" is here intended to be understood as direct electrical contact, i.e., in particular ohmic contact, without the insertion of other electrical components). The first contact portion is referred to here as the top contact portion, but according to Warren's convention, it can also be referred to as a T-contact portion ("T" stands for top). The second contact portion is typically arranged on the rear side surface of the solar cell facing away from the incident light and electrically contacts the side of the bottom cell facing away from the top cell. The second contact portion is referred to here as the bottom contact portion, but according to Warren's convention, it can also be referred to as an R-contact portion ("R" stands for root or root portion). The third contact portion can, for example, be arranged in the plane between the top cell and the bottom cell. However, as will be elaborated in more detail below, the third contact portion can also be spatially arranged on the rear side surface of the solar cell, and the bottom cell and the third contact portion can be configured such that the current dominant at the interface between the top cell and the bottom cell discharges through the third contact portion. In both cases, the third contact portion electrically contacts the interface between the top cell and the bottom cell. In this case, the third contact portion electrically contacts the side of the bottom cell opposite to the side contacted by the bottom contact portion and has a polarity opposite to the region of the bottom cell contacted by the bottom contact portion, such that the voltage generated at the bottom cell can be tapped off via the bottom contact portion and the third contact portion. In addition, the third contact portion electrically contacts the side of the top cell opposite to the side contacted by the top contact portion and has a polarity opposite to the region of the top cell contacted by the top contact portion, such that the voltage generated at the top cell can be tapped off via the top contact portion and the third contact portion. The third contact portion is referred to here as the center tap contact portion, but according to Warren's convention, it can also be referred to as a Z-contact portion ("Z" means additional (English: "extra" or "additional")).

[0038] In a conventional solar module, each individual solar module typically includes only one current input connection and only one current output connection through which the solar cells integrated in the solar module can be connected to an external circuit. In this case, multiple solar modules can in each case be interconnected in series and / or in parallel via their individual current input connections and current output connections to form a solar collector as a whole.

[0039] In contrast, the solar modules described herein are intended to include at least two current input connections and / or at least two current output connections. Each solar module preferably should include at least two current input connections and two current output connections. However, at least theoretically, it is conceivable that a solar module serving as the first solar module within a solar collector may include only one current input connection but two current output connections, or a solar module serving as the last solar module within a solar collector may include two current input connections but only one current output connection.

[0040] In this case, the current input connections and the current output connections are electrically connected in a special way to the terminal contacts of the individual solar cells within the solar module.

[0041] The first current input connection is in particular electrically connected to at least one terminal contact of the solar cell closest to the current input end within the solar module - i.e., there are no other solar cells upstream on the current input side and it can thus be regarded as the first solar cell of the solar module. The second current input connection is electrically connected to at least one terminal contact of the solar cell adjacent to the first solar cell, i.e., to the second solar cell within the solar module. In this case, the first and second solar cells are components of the same string. The first current input connection is preferably directly electrically connected to only the first solar cell. The second current input connection can be directly electrically connected to only the second solar cell. Additionally, the second current input connection can also be electrically connected to one of the terminal contacts of the first solar cell, but a terminal contact different from the one to which the first current input connection is connected. Accordingly, there is no direct ohmic electrical connection between the first current input connection and the second current input connection.

[0042] In a similar manner, the first current output connection is connected to at least one terminal contact of the last solar cell closest to the current output end, and the second current output connection is connected to at least one terminal contact of the penultimate solar cell adjacent to the last solar cell. In this case, the last and the penultimate solar cells are components of the same string. In this case, the first current output connection is also preferably directly electrically connected to only the last solar cell of the solar module. The second current output connection can be directly electrically connected to only the penultimate solar cell. Furthermore, the second current output connection can also be connected to one of the terminal contacts of the last solar cell, but a terminal contact different from the one to which the first current output connection is connected. Accordingly, there is no direct ohmic electrical connection between the first current output connection and the second current output connection.

[0043] Provided are at least two electrically separated current input connections and / or at least two separated current output connections, and a particular way in which these connections are connected to individual solar cells within a solar module, such that in particular different partial solar cells, namely top cells and bottom cells, can be interconnected in an advantageous manner within the solar module, such that almost all partial solar cells can operate optimally within an entire solar collector having a plurality of solar modules, i.e., to the benefit of the overall efficiency of the solar collector. In particular, in the case of a conventional solar cell module including 3TT solar cells, at each individual solar module of the solar collector or even at each individual string, the usually occurring string end losses can be largely prevented, or their occurrence can be restricted to the first solar module and / or the last solar module within a solar collector including a plurality of solar modules. This will be explained in more detail below with reference to specific embodiments.

[0044] According to one embodiment, the top cell and the bottom cell of each 3TT solar cell are arranged in an r-type configuration with opposite polarities. In addition, a first current input connection is connected to the central tap contact of the first 3TT solar cell, and a second current input connection is connected to the central tap contact of the second solar cell. Alternatively or additionally, a first current output connection is connected to the top contact of the last 3TT solar cell, and a second current output connection is connected to the top contact of the penultimate 3TT solar cell.

[0045] In other words, in this embodiment, the top cell and the bottom cell of the 3TT solar cell are oriented with opposite polarities, i.e., for example, the forward direction of the top cell is from the central tap contact towards the top contact, and the forward direction of the bottom cell is from the central tap contact towards the bottom contact. This embodiment is also referred to as an r-type configuration, where "r" stands for "reverse". In contrast, in the case of the known s-type configuration, the top solar cell and the bottom solar cell are oriented identically and are thus connected in series. In the case of the solar module described herein, the r-type configuration allows for particularly advantageous connection of 3TT solar cells to each other and to at least two current input connections or at least two current output connections, respectively.

[0046] In this case, the first current input connection can preferably be electrically contacted only via the central tap contact of the first 3TT solar cell of the solar module, in particular. Then, the second current input connection is placed in electrical contact with the central tap contact of the second 3TT solar cell of the solar module, and the second current input connection can additionally be placed in electrical contact with the bottom contact of the first 3TT solar cell. Alternatively or additionally, the first current output connection is preferably placed in electrical contact only with the top contact of the last 3TT solar cell of the solar module. Then, the second current output connection is placed in electrical contact with the top contact of the penultimate 3TT solar cell of the solar module, and the second current output connection can additionally be placed in electrical contact with the bottom contact of the last 3TT solar cell of the solar module.

[0047] The described r-type configuration, together with the special connection method to the connections, can connect the 3TT solar cells to each other and to a plurality of input and output connections in an advantageous manner, in particular in a manner that requires relatively few wires, such that the occurrence of losses, especially series-end losses, can be limited to a large extent.

[0048] This applies in particular to the case where the voltage generated by the top cell and the voltage generated by the bottom cell are in a specific ratio to each other.

[0049] According to one embodiment, for example, the voltage generated by the top cell when exposed to light and the voltage generated by the bottom cell when exposed to light can be substantially in the ratio of m to n. In this case, m and n are natural numbers. In this case, "substantially" can be understood, for example, to mean that the ratio of the actually occurring voltages in the top cell and the bottom cell differs from the ratio (m:n) by less than 25%, preferably less than 15%, more preferably less than 5%. In this case, n top cells connected in series can be connected in parallel with m bottom cells connected in series in each case.

[0050] In other words, the top cell and the bottom cell can be configured, for example, due to an appropriate selection of the materials and / or doping used for their production, such that the voltages generated by them during combined illumination, i.e., preferably the voltage V at their maximum power point mpp are substantially in an integer ratio to each other. Correspondingly, when illuminated, n top cells connected in series can generate a voltage substantially the same as that of m bottom cells connected in series and connected in parallel with them. The voltage regulation between the described partial solar cells is also referred to as voltage matching of the string (voltage matching string).

[0051] In this case, according to a particular embodiment, it may be the case that: m≥2, n≥1. Thus, the number of current input connections and / or the number of current output connections corresponds to the greater of the two values m and n (in the case of an r-type configuration), or is greater than the greater of the two values m and n (in the case of an s-type configuration).

[0052] In other words, the number of current input connections and / or current output connections provided on the solar module can be related to the way in which the top cells and the bottom cells match each other in terms of the voltage they generate, and can thus be connected in a matching manner to form a group consisting of a plurality of top cells connected in series, in parallel with a group of a plurality of bottom cells connected in series.

[0053] According to a particular embodiment, for example, it may be the case that: m = 2, n = 1. In this case, each bottom contact of the solar cells, except for the last 3TT solar cell, can be connected to the tap contact of the next adjacent 3TT solar cell, and each top contact of the solar cells, except for the last and the penultimate 3TT solar cells, can be connected to the center tap contact of the next next 3TT solar cell.

[0054] Due to the prevention of losses, especially end losses, this matching of the voltages generated by the top cells and the bottom cells in a 2:1 ratio, together with the said interconnection of the top cells and the bottom cells of the plurality of 3TT solar cells, can allow for a particularly simple overall connection within the solar module, while having high efficiency.

[0055] According to one embodiment, in each string, a first bypass diode is connected in parallel with the 3TT solar cells of that string. In addition, in each string, a second bypass diode is connected in parallel with the top cell of the last 3TT solar cell of that string.

[0056] Like all diodes, a bypass diode allows significant current flow only in one direction, namely in its forward direction. In the case of a solar cell module, the bypass diodes are typically connected in anti-parallel, for example, to a string of solar cells such that, in the normal operating state, i.e., when all solar cells are operating properly and generating current, they are polarized in the opposite direction. However, if one (or more) solar cell does not deliver any current, e.g., due to shading, it acts as an electrical load. The current generated by the other solar cells must flow through this load, which may generate significant heat and may cause so-called hot spots. In addition, the total current flowing through the solar module typically depends on the weakest solar cell within the solar module, and thus a single shaded solar cell may significantly limit the efficiency of the solar module. Therefore, to prevent hot spots and reduced yield, in a solar module, the bypass diodes are typically connected in anti-parallel to a string of serially interconnected solar cells. In this case, the cut-off voltage of the bypass diode roughly corresponds to the open-circuit voltage of the solar cells connected in the string.

[0057] In the case of the 3TT solar cell module described herein, as described above, the respective top cells and bottom cells of a plurality of 3TT solar cells can be connected such that, in each case, a first number of top cells are serially interconnected, and a different second number of bottom cells are also serially connected, and the two series circuits are connected in parallel with each other. In this case, for example, the top cells of the 3TT solar cells can, in each case, not be serially connected to the top cell of the directly adjacent 3TT solar cell, but only to the top cell of the next-next 3TT solar cell. In this case, a first bypass diode can be connected in parallel with the string of 3TT solar cells. However, in the case of the described connection, the top cell of the last 3TT solar cell in the string is not protected by the first bypass diode. Accordingly, it is advantageous to provide a separate second bypass diode for the top cell, which is connected in parallel with the top cell.

[0058] In principle, a second bypass diode of this type may have different characteristics from the first bypass diode, since it only needs to protect a single top cell. For example, the open-circuit voltage of the second bypass diode can be lower than the open-circuit voltage of the first bypass diode. However, it can also be provided that all bypass diodes accommodated in the solar module are configured identically.

[0059] According to a particular embodiment, a first bypass diode may be electrically connected on the one hand to the center tap contact of the first 3TT solar cell of a string and on the other hand to the bottom contact or the top contact of the last 3TT solar cell of the string. Additionally, in such a case, a second bypass diode may 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.

[0060] As described below with reference to specific embodiments, this type of connection of the first bypass diode and the second bypass diode may be particularly advantageous for embodiments of a solar module in which the 3TT solar cells are configured in an r-type structure and are matched to each other in a ratio of (2:1) with respect to the voltages of their top and bottom cells.

[0061] According to an alternative embodiment, a solar module may include at least one bypass diode connected across strings, the bypass diode connected across strings being connected on the one hand to a 3TT solar cell upstream of the last 3TT solar cell of an adjacent sub-string (i.e., for example, the penultimate 3TT solar cell) and on the other hand to the last solar cell of the sub-string to be protected.

[0062] In other words, in a solar module, the connection of the bypass diode to the 3TT solar cell may be configured such that at least the last 3TT solar cell in one of the sub-strings is connected to two bypass diodes, namely specifically a bypass diode associated with and connected in parallel with the sub-string in question, and a bypass diode associated with an adjacent sub-string. In such a case, the bypass diode may be connected to the 3TT solar cell in question such that one of the two bypass diodes protects the bottom cell of the 3TT solar 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 preferably possible to avoid providing a separate bypass diode solely for protecting a single top or bottom cell of a single 3TT solar cell, as further discussed above with regard to the second bypass diode.

[0063] According to an alternative embodiment, a solar module may have at least one additional current input connection and / or at least one additional current output connection. In such a case, at least one bypass diode to be connected across the module is accommodated in the solar module. In such a case, the bypass diode to be connected across the module may be connected on the one hand to the additional current input connection and on the other hand to a terminal contact, in particular one of the bottom contacts, 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 may be connected to another current output connection.

[0064] In this embodiment of the solar module, the provision of the second bypass diode for protecting the top cell of the last 3TT solar cell in the string can be omitted. Instead, the top cell can also be protected by the first bypass diode or one of the bypass diodes of the subsequent string, i.e., the bypass diodes connected in this way can act across strings. For this purpose, the subsequent first bypass diode contacts the last top cell of the previous string, in such a way that, for example, in the case of an r-type configuration, it contacts the central contact of the last cell in the string. However, if the top cell to be protected is not only the top cell of the last 3TT solar cell within one of the plurality of strings in the solar module, but also the top cell of the last 3TT solar cell in the entire solar module, then this top cell may not be protected by the first bypass diode from the same solar module. Instead, this top cell is also protected by means of the first bypass diode of an adjacent solar module. To allow the bypass diodes to be connected across modules, for this purpose, at least one further current input connection and / or at least one further current output connection are provided on the solar module, via 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 the solar module is set out below.

[0065] According to another specific embodiment, a plurality of 3TT solar cells are arranged side by side laterally across the entire width of the solar module and are electrically connected to form a sub-string. In this case, both the first bypass diode and the second bypass diode (if present) are arranged laterally beside the sub-string.

[0066] In other words, the solar module can be configured according to the geometric arrangement of the 3TT solar cells accommodated therein such that the plurality of solar cells forming the sub-string are arranged side by side laterally across the entire width of the solar module. Thus, the sub-string contains a relatively large number of stacked solar cells.

[0067] This type of connection in the cell-rich sub-string is particularly suitable for the case where each of the individual partial solar cells has a relatively high reverse electric strength. In this case, it may be advantageous to arrange the first and second bypass diodes laterally beside the sub-string, i.e., on the outer edge of the solar module, in each case. There, the bypass diodes can be particularly easily accessible and / or arranged in a space-saving manner, for example, in the region of the frame of the solar module, where this region locally covers the edge of the solar module.

[0068] According to another alternative embodiment, a plurality of 3TT solar cells are arranged side by side laterally in the first half of the width of the solar module and electrically connected to form a first sub-string, and a plurality of other 3TT solar cells are arranged side by side laterally in the second half of the solar module and electrically connected to form a second sub-string. In this case, the first sub-string and the second sub-string are connected in parallel with each other. In addition, the first bypass diode and the second bypass diode (if present) are both spatially arranged between the first sub-string and the second sub-string.

[0069] In other words, the solar module can be configured according 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 sub-string. In this case, the solar cells connected to form the sub-string are geometrically arranged side by side laterally such that they extend only over half of the width of the solar module. Thus, over the entire width of the solar module, two spatially adjacent sub-strings can be arranged side by side. In this case, the two sub-strings are preferably connected in parallel with each other.

[0070] Since, in the case of this type of connection, the number of solar cells within the sub-string is relatively small, this embodiment is particularly suitable for cases where at least some of the partial solar cells have a relatively low reverse withstand voltage. In this case, it may be advantageous to geometrically arrange the first and second bypass diodes between the first sub-string and the second sub-string in each case. Thus, the bypass diodes can be arranged, for example, within or near the geometric center of the solar module. In this case, a single first bypass diode can be provided for the two sub-strings connected in parallel, which diode is in turn connected in parallel with the two sub-strings. In addition, a separate second bypass diode can be provided for each of the two sub-strings, one second bypass diode being anti-parallel connected to the top cell of the last 3TT solar cell in one of the two sub-strings, and the other second bypass diode being anti-parallel connected to the top cell of the last 3TT solar cell in the other of the two sub-strings. Overall, due to the concentrated arrangement of the bypass diodes between the sub-strings, a favorable overall connection with, for example, short connection distances and correspondingly low resistance losses can be achieved in the solar module.

[0071] According to another specific embodiment, the first bypass diode and the second bypass diode (if present) can be accommodated in a common diode box.

[0072] In this case, the diode box can be, for example, a housing in which the bypass diodes can be accommodated and which can protect the bypass diodes, for example, from environmental influences. Since two bypass diodes can be accommodated in a common diode box, the number of diode boxes required can be kept low. In addition, the design of the solar module with respect to the diode boxes provided therein can be the same as or similar to that of a conventional solar module with only one bypass diode per solar cell string. Thus, the solar module can be produced and / or mounted on its diode boxes in the same way as a conventional solar module.

[0073] According to one embodiment, the top cell is a perovskite solar cell and the bottom cell is a silicon solar cell.

[0074] Silicon solar cells are known for their durability, reliability, and high efficiency. For example, the efficiency of commercially available silicon solar cells can significantly exceed 20%, and they can reliably provide a service life of 20 years or more. However, the efficiency of silicon solar cells is limited, especially since the bandgap of silicon is relatively small, so that high-energy light is usually only converted into electrical energy in the form of heat, with relatively high energy losses.

[0075] Recently, perovskite solar cells have been developed, which can now also offer high efficiency, durability, and reliability, which largely depend on the exact composition of the perovskite used. Generally speaking, perovskite has a much larger bandgap than, for example, silicon, so that solar cells formed therefrom are destined to absorb high-energy light with low losses.

[0076] Accordingly, perovskite solar cells are very suitable for use as a partner to silicon solar cells in tandem solar cells and are used there as the top cell. In this case, the exact composition of the perovskite used is closely related to its bandgap and thus indirectly related to the open-circuit voltage provided by the perovskite solar cell.

[0077] In the case of the method of the solar collector described herein, the perovskite solar cell can be used as the top cell in a 3TT solar cell and, in this case, is optimized, for example, with respect to durability and reliability. In this case, the voltage generated by the top cell during illumination depends on the perovskite used. Depending on the generated voltage, the connections within the solar module and the number of current input connections and current output connections can then be adjusted as described herein in order to be able to achieve a good voltage match between the top cell and the bottom cell within the solar module.

[0078] According to one embodiment, the bottom solar cell may be a back-contact solar cell, wherein the terminal contacts of the two polarities are arranged in a crosswise manner on the rear side of the bottom solar cell facing away from the top solar cell, and one of the terminal contacts of the bottom solar cell serves as a center tap contact.

[0079] Back-contact solar cells, in which the contacts of the two polarities are arranged in a mutually intersecting manner on the rear side of the semiconductor substrate facing away from the light, have long been known and are sometimes also referred to as IBC solar cells (interdigitated back contact). By appropriately adjusting the structures used therein, especially the layer thicknesses, such back-contact solar cells can be adjusted such that they are used as bottom cells in a tandem solar cell, and in which the two types of contacts are not only used to extract the generated current from the bottom cell, but one of the contacts is further electrically connected to the top cell, for example via a tunnel contact, such that the current generated in the top cell can also be extracted together with the top contact. In this case, the contact serves as the center tap contact of the 3TT solar cell, but is not arranged spatially centered between the top cell and the bottom cell, but on the rear side of the bottom cell. Corresponding concepts have been proposed, for example, in document [4] cited in the introduction of the description. Since the center tap contact is arranged on the rear side of the bottom cell, this can be produced relatively simply and also contacted from the outside. Thus, the production of the 3TT solar cell and / or the connection of the 3TT solar cell within a solar module can be significantly simplified.

[0080] According to a second aspect of the invention, the embodiments of the solar module described herein can be used for a solar collector formed thereby. In this case, the property that each solar module includes at least two current input connections and / or two current output connections can be used to interconnect adjacent solar modules, such that losses occurring in the case of solar modules including 3TT solar cells with a conventional design and connection, such as series-end losses, are largely prevented. For this purpose, each current output connection of one solar module is electrically connected to the associated current input connection of one of the adjacent solar modules. In other words, for example, the first current output terminal of the solar module is connected to the first current input terminal of the adjacent solar module, and the second current output terminal of the solar module is connected to the second current input terminal of the adjacent solar module.

[0081] Thus, as will be explained in more detail below with reference to the embodiments, the following situation can be prevented: in each solar module, at least one first 3TT solar cell closest to the current input terminal and / or the last 3TT solar cell closest to the current output terminal may not operate optimally, resulting in the occurrence of said end losses. Instead, due to the special connection proposed herein between adjacent solar modules through at least two output and input connections, such end losses no longer occur in each individual solar module, but ideally only in the first solar module and / or the last solar module of the entire solar collector. Accordingly, the impact of these end losses on the efficiency of the entire solar collector may be significantly reduced.

[0082] According to one embodiment, except for the current input connection of the first solar module and the current output connection of the last solar module of the solar modules, the current input connections of each solar module are electrically isolated from each other, and the current output connections of each solar module are also electrically isolated from each other.

[0083] Furthermore, according to one embodiment, in the case of the first solar module, at least two current input connections are short-circuited or interconnected, and / or in the case of the last solar module, at least two current output connections are short-circuited or interconnected.

[0084] In other words, each current input connection of a solar module is only electrically connected to one of the current output connections of an adjacent solar module, and is not electrically connected to another current input connection of the same solar module or other current output connections of adjacent solar modules. This preferably applies to all solar modules of the solar collector, except for the first solar module and the last solar module. In the case where these two solar modules are located at opposite ends of the series connection of the solar modules within the solar collector, the current input connection of the first solar module and the current output connection of the last solar module are used to connect the entire solar collector to a single external circuit. Accordingly, these two "extreme" current input connections and / or current output connections are electrically interconnected. Accordingly, end losses may not be avoidable at the first solar module and the last solar module, but can be prevented at all solar modules therebetween.

[0085] It should be noted that the possible advantages and configurations of the embodiments of the present invention are described herein in part with reference to the solar modules according to the invention or in part 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 a suitable manner to achieve further embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] The embodiments of the invention will be described below with reference to the accompanying drawings, and the drawings and the description are not intended to be construed as limiting the invention.

[0087] Figure 1 (a)-(d) show the connections of 2TT solar cells, 4TT solar cells, 3TT solar cells in an s-type configuration, and 3TT solar cells in an r-type configuration.

[0088] Figure 2(a) is a schematic cross-sectional view of a 3TT solar cell, which includes a back-contact solar cell as the bottom cell in an r-type configuration.

[0089] Figure 2(b) is a schematic cross-sectional view of a 3TT solar cell, which includes a back-contact solar cell as the bottom cell in an s-type configuration.

[0090] Figure 3 Shows a conventional connection of a 3TT solar cell in an r-type configuration with end-loss generation.

[0091] Figure 4 Shows the connection in a solar module according to the invention, which includes 3TT solar cells in an r-type configuration, each cell having two separate current input terminals and output connections, and a plurality of first and second bypass diodes.

[0092] Figure 5 Shows two solar modules connected to form a solar collector according to the invention.

[0093] Figure 6 Shows the connection in a solar module according to the invention, which includes 3TT solar cells in an r-type configuration, having bypass diodes connected across the strings and each having three separate current input and output connections for allowing the connection of bypass diodes across the modules.

[0094] Figure 7 Shows the geometric arrangement and connection of bypass diodes in a solar module according to the invention.

[0095] Figure 8 Shows an alternative geometric arrangement and connection of bypass diodes in another solar module according to the invention.

[0096] The accompanying drawings are only schematic and not to scale. In particular, it should be noted that the dimensions shown in the figures are not a true reproduction but are only for illustration of the basic principles. The same reference numerals in different drawings represent the same or functionally equivalent features. Detailed Description of the Invention

[0097] As Figure 1As shown by the various embodiments and connections in (a)-(d), as part of the corresponding solar module 19, a plurality of stacked or laminated solar cells 1 provide the possibility of achieving significantly higher efficiency compared to a solar cell having only one p-n junction by absorbing different spectral parts in partial cells stacked on top of each other in the form of a top cell 3 and a bottom cell 5.

[0098] As Figure 1 As shown in (a), if partial solar cells 3, 5 are stacked on top of each other and connected in series to form a two-terminal laminated solar cell 7 (i.e., a cell having two connections or contact parts), losses may occur due to current mismatch. This is caused on the one hand by the fact that, due to technical boundary conditions, the bandgaps of the two partial solar cells 3, 5 are usually not optimally selected, and one partial solar cell generates a higher current than the other. The lower partial cell current limits the total current of the 2TT solar cell. On the other hand, in the case of optimally selected bandgaps, for example due to changes in the irradiation spectrum, a current mismatch effect may also occur.

[0099] As Figure 1 As shown in (b), if the individual partial solar cells 3, 5 are contacted and connected separately, losses caused by current mismatch can be prevented. For this purpose, the laminated solar cell 1 includes four connections or contact parts, i.e., in each case two connections for each partial solar cell 3, 5, and is therefore referred to as a four-terminal laminated solar cell 9. In this case, the corresponding partial solar cells 3, 5 can operate at their optimal operating points. However, for this purpose, all partial solar cells must be processed, contacted, and connected separately, which usually means increased expenditure and optical shading.

[0100] As Figure 1 As shown in (c) and 1(d), a laminated solar cell 1 having 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 a so-called s-type configuration, in which the top cell 3 and the bottom cell 5 are polarized in the same direction and are thus connected in series. Figure 1 (d) shows a so-called r-type configuration, in which the top cell 3 and the bottom cell 5 are polarized in opposite directions, i.e., "in reverse".

[0101] An attractive variant of the 3TT solar cell 11 is to use the bottom cell 5 as an IBC solar cell, which has two rear contact parts arranged crosswise to each other and a contact part on the front side allowing contact with the top cell 3. The design of such a 3TT solar cell 11 is illustrated in the document [4] cited in the introduction of this specification.

[0102] Figures 2(a) and 2(b) show an embodiment of such a 3TT solar cell 11, the contact arrangement and designation of which are carried out according to the convention of Warren et al. (see reference [9] cited in the introduction of this specification). In this case, the same doping is reproduced in the same shading manner in the figures in each case. The 3TT solar cell can be produced in different types, which can be divided into "reverse" connection, i.e., the r-type configuration as shown in Fig. 2(a), and "series" connection, the s-type configuration as shown in Fig. 2. Since the connection is simpler, the "reverse" variant will be mainly discussed below. 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 facing away from the bottom cell 5. The bottom contact 15 or R-contact (representing "raiz" or "root") is the contact of the two rear-side contacts of the bottom cell 5, which has a polarity opposite to that of the front-side contact of the bottom cell. In this case, 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 (representing "zusaetzlich") is a rear contact having the same polarity as the front side of the bottom cell, i.e., an additional contact, in order to extract charge carriers. Thus, the center tap contact electrically contacts the side of the bottom cell 5 opposite to the side contacted by the bottom contact 15, and has a polarity opposite to that of the bottom contact 15. Therefore, the center tap contact 17 is also capable of extracting the charge carriers that have been separated in 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 can be geometrically arranged between the top cell 3 and the bottom cell 5. However, in the case of rear-side contact, similar to the case of the 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 in this case serves as an electrical connection to the interface between the top cell 3 and the bottom cell 5.

[0103] Figures 2(a) and 2(b) additionally show the voltages between the respective terminal contacts 13, 15, and 17. In this case, V top is the voltage generated by the top cell 3, V bot is the voltage generated by the bottom cell 5. V RT is the voltage dominant between the bottom contact 15 and the top contact 13, V ZT is the voltage dominant between the center tap contact 17 and the top contact 13, V RZ is the voltage dominant between the bottom contact 15 and the center tap contact 17.

[0104] The advantages of the 3TT solar cell include in particular:

[0105] (i) The resulting solar cell module can operate as a bifacial tandem component in the free field because the top and bottom solar cells do not have to have the same current. This avoids significant market entry barriers because the additional yield of the tandem module has to be measured not only against single-sided silicon modules but also against bifacial silicon modules. Compared with single-sided photovoltaic modules of the same efficiency, the additional yield of these modules is about 5% - 20%, depending on the usage mode and location of use;

[0106] (ii) Small losses may occur if the bandgap or voltage at the maximum power point is not optimally adjusted. Therefore, the top cell 3 can be selected according to other criteria, such as the reliability or efficiency of the top cell;

[0107] (iii) In a solar cell string, for each additional solar cell, the voltage increases only due to the voltage of the bottom cell and not due to the combined voltage of the bottom cell and the top cell. This allows more photovoltaic modules per module jumper wire, and thus fewer cables are required in the system design.

[0108] As Figure 1 (c) and Figure 1 (d) show in the partial views, the 3TT solar cell 11 can be integrated into the solar module 19 by a combination of series and parallel connections. Since the voltage generated by the top cell 3 is significantly higher than that of 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 facing away from the bottom cell 5, is guided to the contact of the opposite polarity of the next 3TT solar cell 11, i.e., the center tap contact 17.

[0109] Since there is no next-next 3TT solar cell 11 at the end of the string, the losses here occur on the order of the power of one to two 3TT solar cells, depending on the design or configuration of the cell and / or the connection method. Since the introduction of 3TT solar cells, for example in the literature [5] cited in the introduction of the specification, the losses at the string ends have been theoretically studied, for example in the literature [2] cited in the introduction of the specification, and the considerations for adjusting the voltage by connecting the cells have been discussed. The literature

[10] presents possible connection techniques for 3T series photovoltaic modules. Accordingly, there is a practical solution for the connection of 3TT solar cells in a solar module. In this case, it should be noted that, unlike the connection of 3TT solar cells described in the literature

[10] by means of a common connector structure - and thus different methods are used to connect or wire the various terminal contacts of the 3TT solar cells to the common connector structure -, alternatively, continuous connectors can also be used, through which adjacent solar cells are usually contacted and connected within the module, usually with a single connector leading from the front side of the 3TT solar cell to the rear side of the adjacent 3TT solar cell.

[0110] Figure 3 Possible conventional connection methods of the 3TT solar cell 11 are shown, namely a combination of series and parallel connections for module integration. In each case, there are two terminals 23 at both ends of the string 21. These terminals are usually interconnected by an electrical connector 25 so that the current generated by the string 21 can be extracted from the solar module 19 at the current input connection 27 and the current output connection 29. In other words, the connector 25 at each string end ensures that the current generated in the string 21 can be extracted from the string 21.

[0111] However, the bottom cell 5' of the first 3TT solar cell 11' of the string 21 ( Figure 3The leftmost one (in the leftmost part) is short-circuited by the connector 25, and its power is not extracted. In addition, at the ends of each string, that is, at the first 3TT solar cell 11' and the last 3TT solar cell 11", the top cells 3' and 3" there only operate at about 50% of their voltage. This will result in losses, also known as string-end losses. In the case shown, the losses are on the order of the power of one 3TT solar cell. In addition, connecting the terminals 23 using the connector 25 enables the common bypass diode 31 to be connected in parallel with all the 3TT solar cells 11 of the string 21 - including all the top cells 3 and bottom cells 5. This means that string-end losses will occur when each bypass diode is integrated. In the case of a typical string length of 20 cells currently, this process will result in a power loss of about 5%, which usually more than compensates for the advantage of 3TT solar cells over 2TT solar cells. In the case of perovskite solar cells, usually the string length of each bypass diode is very small, so the impact of end losses is even greater.

[0112] The methods discussed in this patent application discuss two methods of transferring string-end losses from the module level (usually having about 60 cells) or the sub-string level (usually 1 / 3 of a module having about 20 cells) to the system level, such as a solar collector (usually having up to 2000 cells), to minimize their relative contributions, and also address the favorable selection of integrating bypass diodes.

[0113] Specifically, embodiments of the present invention relate to the following aspects:

[0114] (i) Electrical connections between solar modules to form a solar collector having, for example, a cable with two cores or two cables;

[0115] (ii) Integration of bypass diodes without the need to connect the contacts or terminals together at the ends of the string;

[0116] (iii) Module design of the modules at the center and ends of the string through external combination of contacts (such as module contacts combined outside the module), for example, through a suitable plug or connector.

[0117] Figure 4 An embodiment of a solar module 19 according to the present invention is shown, in which the 3TT solar cells 11 are connected together in a special manner and connected to two current input connections 27', 27' and two current output connections 29', 29'. In addition, in this case, at least one first bypass diode 33 and one second bypass diode 35 are also provided in each of the two sub-strings 21', 21' shown in the example.

[0118] Figure 5Shows how two solar modules 19 according to the invention can be connected to form a solar collector 37 according to the invention. In this case, it should be noted that an actual solar collector of course usually includes more than two solar modules 19, but the principle of wiring can be clearly determined based on this simplified example.

[0119] Regarding the above aspect (i), Figure 4 and Figure 5 Shows that in each case, all string ends of different potentials are led out to the terminal contacts in the form of two current input connections 27 and current output connections 29. Thus, multiple sub-strings 21', 21" of adjacent solar modules 19 are connected beyond the physical limits of the solar module 1 to form a total string. In each case, the interconnection of the solar modules 19 by two current input connectors 27 and current output connectors 29 enables the provision of the next-next bottom cell 5 for parallel connection to all top cells 3 in the entire string (except for the top cell 3 of the last 3TT solar cell 11) in each case, and extends the connection concept beyond the module limits. Thus, the string end losses that may occur in each sub-string 21', 21' in parallel with the bypass diode 31 (i.e., usually having 20 or fewer cells in each case) are transferred to the system level of a system having multiple interconnected solar modules 1 (usually having up to 2000 or more cells), thereby reducing the relative contribution of the string end losses by two orders of magnitude (i.e., from 1 / 20 = 5% to 1 / 2000 = 0.05%).

[0120] Regarding the above aspect (ii), Figure 4 and Figure 5 Schematically shows the integration of the first bypass diode 33 and the second bypass diode 35. Similar to the case of current 2TT solar cells or single-junction solar cell solar modules, the first bypass diode 33 (shown in the figure as extending at the lower part) protects the corresponding sub-strings 21', 21". However, in this case, the last top cell 3" of each sub-string 21', 21" is not protected and is thus protected by a separate second diode 35.

[0121] At the end of the entire string extending over multiple solar cell modules 19, due to the described connection, the ends 43 of the entire string must be brought together for connection to a power electronics device or an inverter in general, so as to discharge the generated current from the three parallel strings. In this case, the first stranded wire includes a first plurality of respectively next-next top cells 3 connected in series in each case, the second stranded wire includes a second plurality of respectively also next-next other top cells 3 connected in series in each case, and the third stranded wire includes a plurality of respectively next bottom cells connected in series in each case.

[0122] It should be noted that Figures 3 to 5 the examples shown apply in each case to the voltage V generated by the top cell 3 during illumination top which is approximately twice the voltage V of the bottom cell 5 bot , i.e., the ratio V top / V bot is an integer ratio (m:n), which is (2:1) in a specific case. Thus, the connection described in each case includes n = 1 top cell 3 connected in series, which is connected in parallel with m = 2 bottom cells 5 connected in series. In this case, m = 2 mutually parallel stranded wires providing the series top cells 3 are provided.

[0123] It should be noted that, in general, the voltage ratio of the top and bottom cells can be adapted (i.e., "matched") to each other in another way in an integer ratio m:n, e.g., V top / V bot =(m:n)=(3:2) (not shown in the figure).

[0124] Figure 6 Another embodiment of the solar cell module 1 is shown, which is different from Figure 4 and Figure 5 especially in the setting and connection of the bypass diodes, and the way the solar cell module 1 is connected to adjacent modules.

[0125] The solar cell module 1 especially includes a cross-string connected bypass diode 34, which is located at the center of the solar module 19. The bypass diode is connected on the one hand to the penultimate 3TT cell 11" upstream of the last 3TT solar cell 11" of the previous adjacent sub-string 21", and on the other hand to the last solar cell 11" of the sub-string 21' to be protected. In the example shown, the cross-string connected bypass diode 34 is connected on the one hand to the bottom contact 15 of the penultimate cell 3TT solar cell 11" of the previous adjacent sub-string 21", and on the other hand to the bottom contact 15 of the last solar cell 11" of the sub-string 21' to be protected. In this way, the last solar cell 11" in the previous adjacent sub-string 21" is connected both to the bypass diode 36 associated with its sub-string 21", and to the cross-string bypass diode 34 associated with the adjacent sub-string 21'. Thus, its top cell 3" is also protected, so that the second bypass diode 35 proposed in Figure 4 the embodiment can be omitted.

[0126] In addition, the solar cell module 1 includes another current input connection 27''' attached to the first and second current input connections 27', 27'', and / or another current output connection 29''' attached to the first and second current output connections 29', 29''. In addition, the solar cell module 1 includes at least one bypass diode 36, which is connected such that the 3TT solar cells 11 of the solar module 1 under discussion and at least one 3TT solar cell 11 of an adjacent solar module can be protected. Therefore, the bypass diode is also referred to herein as the bypass diode 36 for cross-module connection.

[0127] In the example shown, the bypass diode 36 for cross-module connection is placed in electrical contact with another current input connection 27''' on the one hand and in electrical contact with the bottom contact portion 15 of one of the 3TT solar cells 11 in the solar module 1 on the other hand. In addition, attached to the bypass diode 36 for cross-module connection, the entire solar module further includes another bypass diode, which is connected as the bypass diode 34 for cross-string as described above. In this case, the bypass diode 34 is connected between the center tap contact portion 17 of the 3TT solar cell 11'' of the sub-string 21'' shown on the left side in the figure - the bottom contact portion 15 of which is contacted by the cross-module bypass diode 36 - and the bottom contact portion 15'' of the last 3TT solar cell 11'' of the sub-string 21'' shown on the left side in the example. However, since the top cell 3 of the last 3TT solar cell 11'' is not protected, the center tap contact portion 17'' of the last 3TT solar cell 11'' is connected to another current output connection 29'''.

[0128] Since in each case now, between adjacent solar modules 1, their another current input connection 27''' is connected to the another current output connection 29''' of the adjacent solar module 1, the cross-module connection bypass diode 36 can also protect the top cell 3 of the last 3TT solar cell 11'' in the adjacent solar module 1. Therefore, in this embodiment, it is possible to omit providing one or more second bypass diodes 35.

[0129] Figure 7 and Figure 8 shows the possible geometric arrangements of the bypass diodes 33 and 35 in the respective sub-strings 21 of the 3TT solar module 19, which have 3TT solar cells 11 with high electrical strength ( Figure 7 ) and low electrical strength ( Figure 8 ).

[0130] In this case, in Figure 7In the illustrated embodiment, a plurality of 3TT solar cells 11 are arranged side by side laterally over the entire width B of the solar module 19 in rows. In the example shown, two such rows are electrically connected to form a sub-string 21'. In this case, the first bypass diode 33 and the second bypass diode 35 are each arranged laterally beside the sub-string 21'. In this case, for example, the bypass diodes 33 and 35 can be arranged close to the side edges of the solar module 19, for example at or below a frame (not shown) enclosing the solar module 19.

[0131] In the figure, the squares represent the 3TT solar cells 11. The lines 39 along the edges of the 3TT solar cells 11 represent the three-pole connections between the solar cells. Practical solutions for such three-pole connections are explained in

[10] . The vertical cap-shaped dots represent the bottom contact portions 15 (R - contacts) connected to the bottom cells 5, the horizontal cap-shaped dots represent the top contact portions 13 (T - contacts) connected to the top cells 3, and the diagonal cap-shaped dots represent the center tap contact portions 17 (Z - contacts) of the 3TT solar cells 11. To keep the contact patterns of the bypass diodes 33, 35 simple, only the contacts with the geometrically closest 3TT solar cells 11 are shown in each case. Through the connections (represented by the lines 39) between the 3TT solar cells 11, the terminal contacts are further guided to additional 3TT solar cells 11 in the string 21. This arrangement includes two parallel rows of solar cells that are connected in series. This geometric arrangement is suitable for solar cells with high reverse electrical strength.

[0132] In contrast, in Figure 8 the illustrated embodiment, a plurality of 3TT solar cells 11 are arranged side by side laterally over the first half B / 2 of the width B of the solar module 19 and are electrically connected to form a first sub-string 21', and a plurality of other 3TT solar cells are arranged side by side laterally over the second half of the width of the solar module 20 and are electrically connected to form a second sub-string 21". In this case, the first sub-string 21' and the second sub-string 21" are connected in parallel with each other. The first bypass diode 33 and the second bypass diode 35 are both arranged laterally between the first sub-string 21' and the second sub-string 21". This type of connection is particularly suitable for 3TT solar cells 11 with low reverse electrical strength.

[0133] In other words, as in the case of half-cell modules, the bypass connection of 3TT solar cells 11 with low reverse electrical strength tolerance can be at the center of the module ( Figure 8). However, the 3TT solar cells 11 are connected in quasi-series within a double string (indicated by the peripheral lines 39). The lead-out contacts can also be connected to the next substring 21 or the next solar module 19. The center tap contact 17 (Z-contact) is broken up by a 3TT solar cell 11 that is not directly located in the center of the module. The contact is established by a wired connection, which, according to the standard, will be led to the next top cell 3 for further connection. This connection can be used as a current tap.

[0134] Figure 7 A particular feature of the geometrical arrangement of the solar cells 11 and the bypass diodes 33, 35 is that in each case two bypass diodes 33, 35 located next to the double string 21 can be combined in one common diode box 41 (for reasons of optimization overview, Figure 7 Thus, for example, a solar module 19 can be constructed using three conventional diode boxes 41. Figure 8 In the geometrical arrangement of the solar cells 11 and the bypass diodes 33, 35 in FIG. 1 , two bypass diodes 33, 35 can be connected in each case in one diode box (for reasons of optimization overview, Figure 8 ), and can therefore again be diode-connected to the conventional three-diode box 41 in the center of the module.

[0135] If the proposed solar modules 19 are connected, then the two current output connections 29', 29" can optionally be short-circuited to a common negative contact and the two current input connections 27', 27" can be short-circuited to a common positive contact, accepting the string end losses, in order to achieve only a single-core connection between the solar modules 19. In this case, the solar modules 19 are connected together in a series manner, so that in each case the negative contact is connected to the positive contact of an adjacent solar module 19. If it is desired to utilize the full connection potential, 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 in series to the second current input connection 27" of an adjacent solar module 19 by means of a two-core connection, i.e., for example using a two-core cable or two cables.

[0136] It should be noted that terms such as "comprising", "having" and the like do not exclude any other elements or steps, and terms such as "a" or "an" and the like do not exclude a plurality. In addition, it should be noted that features or steps that have been described with reference to any one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference numerals in the claims should not be considered as limiting.

[0137] Reference numerals list

[0138] 1 Stacked Solar Cell

[0139] 3 Top Cell

[0140] 3’ Top Cell of the First 3TT Solar Cell

[0141] 3” Top Cell of the Last 3TT Solar Cell

[0142] 5’ Bottom Cell of the First 3TT Solar Cell

[0143] 5” Bottom Cell of the Last 3TT Solar Cell

[0144] 5 Bottom Cell

[0145] 7 2TT Solar Cell

[0146] 9 4TT Solar Cell

[0147] 11 3TT Solar Cell

[0148] 11’ First 3TT Solar Cell

[0149] 11” Last 3TT Solar Cell

[0150] 13 Top Contact

[0151] 15 Bottom Contact

[0152] 17 Center Tap Contact

[0153] 19 Solar Module

[0154] 21 String

[0155] 21’ Sub - string

[0156] 21” Sub - string

[0157] 23 Terminal

[0158] 25 Connector

[0159] 27 Current Input Connection

[0160] 27’ First Current Input Connection

[0161] 27” Second Current Input Connection

[0162] 27”’ Another Current Input Connection

[0163] 29 Current Output Connection

[0164] 29’ First Current Output Connection

[0165] 29” Second Current Output Connection

[0166] 29’’ Another current output connection

[0167] 31 Common bypass diode

[0168] 33 First bypass diode

[0169] 34 Bypass diode for cross - string connection

[0170] 35 Second bypass diode

[0171] 36 Bypass diode for cross - module connection

[0172] 37 Solar collector

[0173] 39 Line indicating series connection

[0174] 41 Diode box

[0175] 43 All series ports

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 connections (27) located at the current input end of the solar module (19) and / or at least two current output connections (29) located at the current output end of the solar module (19); wherein each 3TT solar cell (11) has a stack with a top cell (3) and a bottom cell (5) arranged thereunder, wherein the top cell (3) and the bottom cell (5) are different from each other in terms of the voltage generated when exposed to light; wherein each 3TT solar cell (11) has three terminal contacts including a top contact (13), a bottom contact (15) and a center tap contact (17), the top contact (13) is in electrical contact with the side of the top cell (3) facing away from the bottom cell (5), the bottom contact (15) is in electrical contact with the side of the bottom cell (5) facing away from the top cell (3), and the center tap contact (17) is in electrical contact with the 3TT solar cell at the interface between the top cell (3) and the bottom cell (5); wherein a first current input connection (27') among the current input connections (27) is connected to at least one terminal contact of a first 3TT solar cell (11') among the 3TT solar cells (11) closest to the current input end, and wherein a second current input connection (27") among the current input connections (27) is connected to at least one terminal contact of a second 3TT solar cell among the 3TT solar cells (11) adjacent to the first 3TT solar cell (11'); and / or wherein a first current output connection (29') among the current output connections (29) is connected to at least one terminal contact of a last 3TT solar cell (11") among the 3TT solar cells (11) closest to the current output end, and wherein a second current output connection (29") among the current output connections (29) is connected to at least one terminal contact of a penultimate 3TT solar cell among the 3TT solar cells (11) adjacent to the last 3TT solar cell (11").

2. The 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 opposite polarities; and wherein 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 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 solar module according to any one of the preceding claims, wherein 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 a ratio of m to n, where m and n are natural numbers; and wherein in each case, n top cells (3) connected in series are connected in parallel with m bottom cells (5) connected in series.

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

5. The solar module according to any one of claims 3 and 4, wherein m = 2, n = 1; wherein each bottom contact (15) of the 3TT solar cells (11), except for the last 3TT solar cell (11"), is connected to the center tap contact (17) of the next adjacent 3TT solar cell (11); and wherein each top contact (3) of the 3TT solar cells (11), except for the last 3TT solar cell and the penultimate 3TT solar cell, is connected to the center tap contact (17) of the third next 3TT solar cell (11) behind.

6. The solar module according to any one of the preceding claims, wherein in each of the strings (21), a first bypass diode (33) is connected in parallel with the 3TT solar cells (11) in the string (21), and wherein furthermore 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') in the string (21).

7. The solar module according to claim 6, wherein the first bypass diode (33) is electrically connected on the one hand to the center tap contact (17) of the 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 to the center tap contact (17) of the last 3TT solar cell (11") of the string (21).

8. The solar module according to any one of the preceding claims, wherein the solar module (19) has at least one bypass diode (34) connected across the string; wherein the bypass diode (34) connected across the string is connected on the one hand to a 3TT solar cell (11''') upstream of the last 3TT solar cell (11'') of an adjacent sub-string (21''), and on the other hand to the last solar cell (11''') of the sub-string (21') to be protected.

9. The solar module according to any one of the preceding claims, wherein the solar module (19) has at least one additional current input connection (27''') and / or at least one additional current output connection (29'''); wherein at least one bypass diode (36) to be connected across the module is accommodated in the solar module (19); wherein the bypass diode (36) to be connected across the module is connected on the one hand to the additional 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 wherein the center tap contact (17) of the last 3TT solar cell (11) in the solar module (19) is connected to the additional current output connection (29''').

10. The solar module according to any one of claims 6 to 9, wherein a plurality of 3TT solar cells (11) are arranged side by side laterally over the entire width (B) of the solar module (19) and are electrically connected to form a sub-string (21'); and wherein the first bypass diode (33) and optionally the second bypass diode (35) are arranged laterally beside the sub-string (21').

11. The solar module according to any one of claims 6 to 9, wherein a plurality of 3TT solar cells (11) are arranged side by side laterally in the first half of the width (B) of the solar module (19) and are electrically connected to form a first sub-string (21'), and a plurality of 3TT solar cells (11) are arranged side by side laterally in the second half of the width of the solar cell module (19) and are electrically connected to form a second sub-string (21''), wherein the first sub-string (21') and the second sub-string (21'') are connected in parallel with each other; and wherein the first bypass diode (33) and optionally the second bypass diode (35) are each arranged between the first sub-string (21') and the second sub-string (21'').

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

13. 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. The solar module according to any one of the preceding claims, wherein the bottom solar cell (5) is a back-contact solar cell, wherein the terminal contacts (15, 17) of the two polarities are arranged to cross each other on the rear side of the bottom solar cell (5) facing away from the top solar cell (3), and wherein one of the terminal contacts of the bottom solar cell (5) serves as the center tap contact (17).

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

16. The solar collector according to claim 15, wherein, except for the current input connection (27) of the first solar module (19) in the solar modules (19) and the current output connection (29) of the last solar module in 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. The solar collector according to any one of claims 15 and 16, wherein, in the case of the first solar module (19) in the solar modules (19), the at least two current input connections (27) are electrically short-circuited or interconnected, and / or, in the case of the last solar module (19), the at least two current output connections (29) are electrically short-circuited or interconnected.

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