Photovoltaic system

Abstract

The invention relates to a method for operating a photovoltaic system (10) with two photovoltaic modules (12), wherein the supplied electrical energy is provided with a predefinable DC voltage at a system connection unit (14) with a first and a second system connection (16, 18), - wherein the electrical energy is transmitted via a respective coupling module (20) and via a first and second line (22, 24) connected to the first and second system connection, wherein the coupling modules determine operating data (84) for an operating state of the photovoltaic module (12), - wherein each coupling module determines operating data signals (72) and outputs them to the first or second line, and - wherein an operating state detection unit (26) receives and evaluates the operating data signals emitted by the coupling modules in order to determine the operating data and, depending on the operating data, to determine an operating state of the photovoltaic system. According to the invention, a transmitter unit (66) of the coupling module is signal-technically coupled to the first and second lines (22, 24) via a switching element (114).

Description

[0001] The present invention relates to a photovoltaic system with at least two photovoltaic modules, wherein each of the at least two photovoltaic modules has several photovoltaic cells which provide electrical energy under the influence of light, wherein the photovoltaic cells of each of the at least two photovoltaic modules are electrically connected to one another, a system connection unit for providing the electrical energy provided by the photovoltaic cells of the at least two photovoltaic modules with a predefinable DC voltage, wherein the system connection unit has at least a first system connection for providing a positive electrical potential of the DC voltage and at least a second system connection for providing a negative electrical potential of the DC voltage, and a respective coupling module for each of the at least two photovoltaic modules.wherein the respective coupling module is electrically connected to the respective photovoltaic module, wherein the coupling modules are electrically coupled to provide the electrical energy supplied by the photovoltaic cells of the respective photovoltaic module by means of a first line connected to the at least one first system connection and a second line connected to the at least one second system connection, wherein the coupling modules are configured to determine operating data for at least one operating state of the respective connected photovoltaic module, wherein each coupling module has a first transmitting unit and a first receiving unit and is configured to determine operating data signals according to a predefinable communication protocol depending on the operating data and to transmit the operating data signals at least to the first or at least to the second line, and an operating state detection unit,the invention comprises a second transmitting unit and a second receiving unit, which are signal-technically coupled to the at least one line to which the operating data signals can be transmitted, wherein the operating state detection unit is configured to receive and evaluate the operating data signals transmitted by the coupling modules in order to determine the operating data and, depending on the operating data, to determine an operating state of the photovoltaic system. The invention further relates to a method for operating a photovoltaic system with at least two photovoltaic modules, wherein each of the at least two photovoltaic modules comprises several photovoltaic cells which provide electrical energy under the influence of light, wherein the photovoltaic cells of each of the at least two photovoltaic modules are electrically connected to one another.wherein the electrical energy provided by the photovoltaic cells of the at least two photovoltaic modules is supplied at a predefinable DC voltage to a system connection unit of the photovoltaic system, wherein the system connection unit has at least one first system connection for supplying a positive electrical potential of the DC voltage and at least one second system connection for supplying a negative electrical potential of the DC voltage, wherein the electrical energy provided by the photovoltaic cells of the respective photovoltaic module is transmitted via a respective coupling module of the photovoltaic system electrically connected to the respective photovoltaic module, as well as via a first line connected to the at least one first system connection and a second line connected to the at least one second system connection.wherein the first and second lines are coupled to the coupling module, wherein the coupling modules determine operating data for at least one operating state of the respective connected photovoltaic module, wherein each coupling module has a first transmitting unit and a first receiving unit and determines operating data signals according to a predefined communication protocol depending on the operating data and transmits the operating data signals at least to the first or at least to the second line, and wherein an operating state detection unit of the photovoltaic system, which has a second transmitting unit and a second receiving unit which are signal-technically coupled to the at least one line to which the operating data signals are transmitted, wherein the operating state detection unit receives and evaluates the operating data signals transmitted by the coupling modules,to determine the operating data and, depending on the operating data, to determine the operating state of the photovoltaic system.

[0002] Photovoltaic systems and methods for their operation are extensively known in the prior art, so no separate printed documentation is required. Photovoltaic systems serve to capture light, especially sunlight, and to provide electrical energy or power depending on the light intensity. The electrical power of the photovoltaic system is generally provided by a direct current voltage, which can be supplied to an electrical energy converter or an electrical energy transformer.The electrical energy converter can transform the electrical energy from the photovoltaic system into a desired electrical voltage, allowing the photovoltaic system to be electrically coupled to a power supply network, such as the public grid. In this case, the energy converter can be designed as an inverter, particularly a grid-tied inverter, if the power supply network uses an alternating voltage, such as single-phase or three-phase AC. However, it is also possible to couple the photovoltaic system with an electrical energy storage device, such as a battery storage system with at least one, preferably several, battery cells and / or electrical capacitors.In such a case, the energy converter or energy transformer can be designed, for example, as a DC / DC converter or similar device. Of course, combinations of these are also possible.

[0003] Photovoltaic cells, or photovoltaic modules, are also called solar cells or solar modules. A photovoltaic module can contain multiple photovoltaic cells, which are at least partially connected electrically in series. However, a parallel connection or a combination of parallel and series connections is also possible. Within a photovoltaic module, the photovoltaic cells are usually permanently connected to one another.

[0004] In principle, a similar circuit design can also be used for interconnecting photovoltaic modules. However, photovoltaic modules are preferably connected at least partially in series to achieve a comparatively high DC voltage. This can be advantageous for energy conversion.

[0005] The electrical energy provided by the photovoltaic cells of at least two photovoltaic modules is made available for further use at a system connection unit of the photovoltaic system, which has at least one first connection for providing a positive electrical potential of the DC voltage and at least one second connection for providing a negative electrical potential of the DC voltage. The DC voltage is therefore present as the electrical potential difference between the first and second connections.

[0006] In practical operation of a photovoltaic system, it can happen that the photovoltaic modules are not uniformly exposed to light. Particularly in solar photovoltaic systems designed to generate electrical energy from sunlight, shading of one or more photovoltaic modules can become a problem, especially when the modules are electrically connected in series. This problem is addressed, for example, in DE 10 2011 111 255 A1, which discloses a retrofit kit for upgrading a photovoltaic system. This invention aims to electrically couple each of the at least two photovoltaic modules to the first and second lines via a coupling module connected to the respective photovoltaic module.The coupling module is designed to react to corresponding shading and adjust the available power so that, especially in the case of a series connection of photovoltaic modules, a feedback effect on the further photovoltaic modules connected in series can be largely avoided.

[0007] The coupling module, also called an optimizer, helps to maintain the electrical power output of the photovoltaic system as much as possible, even when one or more photovoltaic modules are shaded. For example, in a series connection of photovoltaic modules, the coupling module can adjust the power output of each individual module to compensate for the shading, thus largely maintaining a constant direct current (DC) in the series circuit. For this purpose, the coupling module can, for example, incorporate a buck converter as a DC / DC converter.

[0008] Since each coupling module is individually electrically connected to a specific photovoltaic module, it is generally standard practice for the coupling module to be able to detect at least one operating state of the respective photovoltaic module and, based on this, determine operating data. The operating state can be, for example, electrical power, electrical current, electrical voltage, temperature, data about the photovoltaic cells of the photovoltaic module, and / or the like. For this purpose, the coupling module can have a sensor unit or be in signal communication with a sensor unit.

[0009] For the proper operation of the photovoltaic system, it is advantageous to have operating data relating to the photovoltaic modules available. In particular, it is desirable to know the operating state of the photovoltaic system. This can be used, among other things, to control the photovoltaic system. For this purpose, it is therefore common practice for each coupling module to determine operating data signals according to a predefined or configurable communication protocol, depending on the operating data, and to transmit these operating data signals to the first and second lines.In this way, the operating data of the respective coupling module can be made available for further use without the need for additional communication paths, because the coupling module, in the manner of powerline technology, uses the first and second lines not only to transmit the electrical energy provided by the photovoltaic modules, but can also serve for communication by transmitting the operating data or operating data signals to the first and second lines.

[0010] The photovoltaic system also includes an operating status monitoring unit, which is likewise connected to the first and second lines via signal transmission. This enables the operating status monitoring unit to receive and evaluate the operating data signals emitted by the coupling modules. The operating status monitoring unit can then derive the operating data from these signals and, based on this data, determine, for example, the operating status of the photovoltaic system. This system operating status can then be accessed via a communication interface of the operating status monitoring unit. In this sense, the operating status monitoring unit can, for example, be configured as a gateway.The communication interface can be, for example, a wired or wireless communication interface, such as an interface to the internet, a mobile communication interface and / or the like.

[0011] Furthermore, US 2006 / 0162772A1 discloses a system and a method for monitoring photovoltaic energy generation systems.

[0012] Even though the current state of the art has proven its worth, there is still room for improvement. It has been shown that the signal coupling between the respective transmitting and receiving units and the lines can impair signal reception, especially when the transmitting and receiving units are coupled to the lines via a common signal coupler.

[0013] The invention is based on the objective of improving the reliability of communication in photovoltaic systems.

[0014] The invention proposes a method and a photovoltaic system according to the independent claims as a solution.

[0015] Advantageous further training opportunities arise from the characteristics of the dependent requirements.

[0016] With regard to a photovoltaic system of the type described, the invention particularly proposes that the respective transmitting unit and the respective receiving unit are coupled in parallel to the at least one line to which the operating data signals can be transmitted, wherein the transmitting unit is coupled to the at least one line by means of a switching element.

[0017] With regard to a generic method, the invention particularly proposes that the respective transmitting unit and the respective receiving unit are coupled in parallel to the at least one line to which the operating data signals can be transmitted, wherein the transmitting unit is coupled to the at least one line depending on a switching state of a switching element.

[0018] The invention is based, among other things, on the idea that the transmitting unit typically provides a low coupling impedance for sending a signal. This is advantageous for transmission because it allows for good coupling of a transmitted signal with high transmission power. However, the low coupling impedance of the transmitting unit proves disadvantageous when receiving transmitted signals because it results in a corresponding attenuation of the received signal. Signal reception by the receiving unit can therefore be impaired, especially if the transmission of signals via at least one of the lines used for power transmission is already subject to comparatively high attenuation for this reason. The invention addresses this problem and teaches that the transmitting unit is coupled to the corresponding line only when needed, specifically for intended transmission operation.The switching element serves this purpose, establishing the signal coupling of the transmitting unit to the at least one line depending on a controllable switching state. The switching state of the switching element can be controlled, for example, by a switching signal provided by a control unit of the coupling module or a control unit of the operating state detection unit, such as its evaluation unit. The switching element thus preferably serves not only to disconnect the transmitting unit from the at least one line, but can also serve to signal-wise disconnect the receiving unit from the transmitting unit depending on the switching state. In particular, it can be provided that the receiving unit is essentially permanently coupled to the at least one line. The typically relatively high input impedance of the receiving unit generally does not have a significant effect on transmission.In principle, the switching element can also be designed, at least partially, as a changeover element, so that, for example, either only the transmitting unit or the receiving unit is connected to at least one line. In principle, a further switching element can also be provided for the receiving unit. With minimal effort, the aforementioned problem can thus be reduced or even completely avoided. Communication can be implemented, for example, using a daisy-chain principle or similar, so that each coupling module is given a predefined or configurable period to transmit its operating data signal. Alternatively, the coupling modules can transmit their operating data signals in a predefined sequence, with each module transmitting its signal only after it has determined that the preceding module has finished transmitting its signal. Other communication scenarios are also conceivable. Unidirectional communication, for instance, allows for high data rates, which can be particularly advantageous for powerline communication.The operating data signals, as well as other signals such as an activation signal, can be implemented as digital or analog signals. The operating data signals and the activation signal may also employ encoding, such as block coding.

[0019] The coupling modules may preferably include a module communication unit connected to or signal-linked to the first and second lines, which allows not only the transmission of operating data signals to the first and second lines, but also the reception and evaluation of the activation signal or other signals, and the provision of the corresponding data from these signals for use within the coupling module. Preferably, the module communication unit comprises the transmitter and receiver units of the coupling module.

[0020] Accordingly, the operating status monitoring unit can include a monitoring communication unit that is also signal-linked to or connected to the first and / or second line, so that, for example, the corresponding operating data signals from the coupling modules can be received and evaluated, and the activation signal can be transmitted. Preferably, the monitoring communication unit includes the transmitting and receiving units of the operating status monitoring unit.

[0021] The activation signal allows, for example, bidirectional communication between the coupling modules and the operating status monitoring unit to be activated as needed. Therefore, bidirectional communication does not need to be permanently enabled for the intended operation of the photovoltaic system. This minimizes communication overhead. Furthermore, bidirectional communication can be activated only when required to improve the determination of the system's operating status. The bidirectional communication mode enables the control of the coupling modules, particularly regarding the acquisition of operating status. Specifically, it allows for the synchronization of operating status acquisition by the coupling modules. This, among other things, allows for a more precise determination of the system's operating status.

[0022] This also makes it possible to reliably identify malfunctions or maintenance requirements and to provide corresponding data via the communication interface. Overall, this can improve the function and intended operation of the photovoltaic system.

[0023] At least the coupling module or the operating state detection unit can include at least one program-controlled computer unit with which at least part of the functionality of the coupling module or the operating state detection unit can be implemented. In particular, the computer unit can serve to provide at least the operating data signals to the coupling module or at least the activation signal to the operating state detection unit. Furthermore, the respective computer unit can be designed to implement additional functionalities, such as control functionalities, monitoring functionalities, and / or the like.

[0024] The coupling module or operating state monitoring unit can, in particular, comprise one or more computing units, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more systems-on-a-chip (SoCs). The coupling module or operating state monitoring unit can also contain one or more processors, for example, one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs).The coupling module or operating status monitoring unit can also include one or more hardware and / or software interfaces, for example for receiving and / or providing data.

[0025] The coupling module or operating state detection unit can also include one or more memory devices. A memory device can be implemented as volatile memory, for example as dynamic random access memory (DRAM) or static random access memory (SRAM), or as non-volatile data storage, for example as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or flash EEPROM, ferroelectric random access memory (FRAM), magnetoresistive random access memory (MRAM), or phase-change random access memory (PCRAM).

[0026] The system connection unit serves to enable an electrical connection for the transfer of energy generated by the photovoltaic cells. It can be implemented as a virtual interface or system boundary and does not necessarily need to be a physical unit. Instead, the system connection unit can also be implemented using connecting cables, for example, to an electrical device that receives the energy generated by the photovoltaic cells. Alternatively, the system connection unit can also be formed by one or more connection points of one or more inverters.

[0027] For example, the connection contacts can also be those of an inverter. Furthermore, it is of course possible that the system connection unit is a physical component of the photovoltaic system, by means of which an electrical connection to the photovoltaic system can be established.

[0028] According to one embodiment, it is proposed that the switching element be designed as an electromechanical switching element. The switching element can, for example, be designed as a relay.

[0029] Furthermore, it is proposed that the switching element be designed as an electronic switching element. The electronic switching element can enable a fast, and in particular, low-bounce switching operation. The electronic switching element can, of course, also be combined with the electromechanical switching element.

[0030] Furthermore, it is proposed that the electronic switching element include at least one transistor operating in switching mode. With a single transistor, the electronic switching element can be implemented in a cost-effective and simple manner. Of course, the electronic switching element can also include more than one transistor. The transistor can be a bipolar transistor or a field-effect transistor, in particular a MOSFET. The transistor is operated in switching mode, so that it essentially exhibits the behavior of an electromechanical switching element.

[0031] It is further proposed that the electronic switching element comprises at least two transistors operating in switching mode, wherein the transistors are connected in antiparallel or antiseries configurations. This allows switching functionality to be achieved similar to that of an electromechanical switching element, namely, in particular, that an electric current can flow in both directions when the switching is on. Furthermore, it can be achieved that, in the switching-off state, an electrical voltage, regardless of its polarity, does not result in a significant current flow. Antiseries-in-series connection is particularly suitable for transistors that incorporate an integrated inverse diode.

[0032] It is further proposed that the signal coupling of the transmitting unit and the receiving unit with the at least one line to which the operating data signals can be transmitted be achieved by means of a signal coupler to which the receiving unit and the switching element are connected in parallel. Thus, the signal coupling can be implemented with only one component. The signal coupler is preferably designed to couple signals with large power differences.

[0033] Furthermore, it is proposed that the signal coupler be designed to provide galvanic isolation between the at least one line to which the operating data signals can be transmitted, on the one hand, and the transmitting and receiving units, on the other. This makes it possible to achieve galvanic isolation between the at least one line and the transmitting and receiving units.

[0034] According to a beneficial further development, it is proposed that the communication modules activate bidirectional communication depending on the receipt of the activation signal. This allows the coupling modules to communicate individually with the operating status monitoring unit, for example, to transmit specific additional data that cannot be transmitted in a unidirectional data transmission, or to transmit specific data to the operating status monitoring unit based on the receipt of a query signal from the unit, or similar applications. Numerous other applications and combinations thereof are conceivable. The bidirectional communication mode can be activated automatically in the coupling modules.It can also be stipulated that the bidirectional communication mode is only activated after a predetermined or configurable period of time has elapsed. This allows, for example, the transmission of outstanding operational data signals before the bidirectional communication mode is activated.

[0035] It is further proposed that the operating state monitoring unit determines the plant operating state at a predetermined acquisition time from the transmitted operating data. The operating state monitoring unit receives the corresponding operating data signals and can preferably determine, based on these signals, that the operating data was acquired at the acquisition time. The operating state monitoring unit can then preferably only use those operating data to determine the plant operating state that it has determined were acquired at the predetermined acquisition time. This enables the operating state monitoring unit to determine the plant operating state at the predetermined acquisition time. The operating data signals can, for example, contain data regarding the time of acquisition. The data can include, among other things, the acquisition time.

[0036] The advantages and effects described for the method according to the invention also apply equally to the photovoltaic system according to the invention, and vice versa. Method features can therefore also be formulated as device features, or vice versa.

[0037] The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combination specified but also in other combinations without leaving the scope of the invention.

[0038] The embodiments described below are preferred embodiments of the invention. The features and combinations of features specified above in the description, as well as those mentioned in the following description of embodiments and / or shown individually in the figures, are not only usable in the combinations specified, but also in other combinations. Thus, embodiments are also encompassed by the invention or are considered disclosed that are not explicitly shown and explained in the figures, but can be derived and generated from the described embodiments by separate combinations of features.The features, functions, and / or effects illustrated by the exemplary embodiments can each, considered independently, represent individual features, functions, and / or effects of the invention, each of which further develops the invention independently. Therefore, the exemplary embodiments are intended to include combinations other than those described in the embodiments. Furthermore, the described embodiments can also be supplemented by additional features, functions, and / or effects of the invention already described.

[0039] In the figures, the same reference symbols denote the same features or functions.

[0040] The figures show: Fig. 1 A schematic block diagram of a photovoltaic system with a plurality of photovoltaic modules arranged in three strings, each photovoltaic module being connected to a respective coupling module, via which the solar module is electrically coupled to an inverter assigned to a respective string, and with an operating status monitoring unit, Fig. 2 a schematic block diagram representation of one of the photovoltaic modules connected to the respective coupling module according to Fig. 1, Fig. 3 a schematic block diagram representation of the operating status detection unit according to Fig. 1, Fig. 4 a schematic signal representation of an operating data signal of a coupling module according to Fig. 2, and Fig. 5 a schematic signal representation of an activation signal of the operating state detection unit according to Fig. 3.

[0041] Fig. Figure 1 shows a schematic block diagram of a photovoltaic system 10 with nine photovoltaic modules 12, arranged in three strings 34, 36, 38. Each string 34, 36, 38 comprises three photovoltaic modules 12. The photovoltaic modules 12 are designed as solar modules. Each photovoltaic module 12 has a plurality of photovoltaic cells, which are designed as solar cells. The solar cells generate electrical energy when exposed to light, especially sunlight. Within each photovoltaic module 12, the individual photovoltaic cells are electrically connected to one another. The electrical connection can be, for example, a series connection, a parallel connection, or a combination thereof.

[0042] The photovoltaic system 10 further comprises a system connection unit 14, which serves to supply the electrical energy generated by the photovoltaic cells of the photovoltaic modules 12 at a predefinable DC voltage. In the present embodiment, the system connection unit is provided for each of the strings 34, 36, 38 with a first system connection 16 for supplying a positive electrical potential of the DC voltage and a second system connection 18 for supplying a negative electrical potential of the DC voltage. For each of the strings 34, 36, 38, a corresponding inverter 100 is provided, which has a DC voltage output side connected to the respective system connections 16, 18 of the respective string 34, 36, 38. The inverters 100 are designed as grid-tie inverters and are connected in parallel on the AC side and connected to a public power supply network 102.The power supply network 102 is, in the present case, a power supply network that operates with an alternating voltage of approximately 230 V at approximately 50 Hz. In alternative embodiments, it is of course possible for the AC voltage network 102 to be designed as a three-phase AC voltage network, which can be operated with an effective network AC voltage of approximately 400 V. However, the invention is independent of this.

[0043] The DC voltage between the system connections 14, 16 is preferably about 350 V, so that this DC voltage can be used by the inverters 100 without the need for an additional DC voltage conversion. In alternative embodiments, however, the inverters 100 may additionally include a DC voltage converter that converts the DC voltage applied to the DC-side connection of the inverter to a potential required for the inverter operation.

[0044] Out of Fig. Figure 1 further shows that each photovoltaic module 12 is electrically connected to a respective coupling module 20. For this purpose, the coupling module 20 has a first module connection 50, which serves to connect the respective photovoltaic module 12. In the present embodiment, the first module connection has two connection contacts, PV+ and PVauf, via which the photovoltaic module 12 is electrically connected to the coupling module 20.

[0045] The coupling module 12 also has a second module connection 52, to which the electrical energy or power supplied by the photovoltaic module 12 can be provided. In the present embodiment, the three photovoltaic modules 12 of each string 34, 36, 38 are connected in series via their respective coupling modules 20 within each of the strings 34, 36, 38. This means that the second module connections 52 of the coupling modules 20 of each string 34, 36, 38 are connected in series. Thus, the series connection of the second module connections 52 of each of the strings 34, 36, 38 determines the DC voltage between the respective system connections 16, 18. The series connection of the photovoltaic modules 12 of each string 34, 36, 38 is therefore indirectly realized by means of the coupling modules 20.

[0046] Fig. Figure 2 shows a schematic block diagram of one of the coupling modules 20 connected to the respective photovoltaic module 12 according to Fig. 1. From Fig. As can be seen in Figure 2, the coupling module 20 has an energy converter, which in this case is designed as a buck converter 48. The buck converter 48 establishes a power coupling between the first module connection 50 and the second module connection 52. The basic function of the buck converter 48 is known to those skilled in the art, which is why a detailed explanation is omitted here.

[0047] Out of Fig. Figure 2 further shows that the second module connection 52 has a first terminal 54 and a second terminal 56, between which a partial DC voltage is supplied, which is specified by means of the buck converter 48. It can also be seen that the buck converter 48 is coupled to the second terminal 56 via a first filter circuit 58. The function of the filter circuit 58 will be explained in more detail below.

[0048] The coupling module 20 also includes a sensor unit 60, which can detect electrical voltage and current at both the first module terminal 50 and the second module terminal 52. This makes it possible, among other things, to determine the electrical power supplied by the connected photovoltaic module 12. Furthermore, the coupling module 20 includes a power supply unit 62, which is connected to the first module terminal 50 and supplies the coupling module 20 and its components with electrical energy for their intended operation.

[0049] The coupling module 20 also includes a control unit 64, which, among other things, communicates with the sensor unit 60. The control unit 64 can evaluate sensor signals from the sensor unit 60 and generate operating data 84 for at least one operating state of the connected photovoltaic module 12. Fig. 4) determine. In the present embodiment, it is provided that the operating data 84 include, among other things, an instantaneous electrical power of the connected photovoltaic module 12, an operating voltage and an operating current at the first module connection 50. Alternatively or additionally, other operating states that may be included in the operating data can of course also be recorded, for example a temperature of the photovoltaic module 12 and / or the like.

[0050] The coupling module 20 further comprises a module communication unit 70, which includes a transmitter unit 66 and a receiver unit 68. The module communication unit 70 also includes a signal coupler 104, via which the transmitter unit 66 and the receiver unit 68 can be coupled using the connection contacts 54 and 56, respectively. The receiver unit 68 is directly electrically connected to the signal coupler 104. In contrast, the transmitter unit 66 is not directly connected to the signal coupler 104. Rather, the transmitter unit 66 is connected to the signal coupler 104 via an electronic switching element 114. The switching state of the switching element 114 is controlled by a switching signal provided by the control unit 64. The control unit 64 provides the switching signal, among other things, depending on the fact that no other communication participants are active.The control unit 64 switches the switching element 114 to the on state only when the transmitter unit 66 is operating in transmit mode. Otherwise, the switching element 114 is in the off state. This allows a small impedance of the transmitter unit 66 to be deactivated during receive operation of the receiver unit 68, thereby improving the reception of signals, especially the operating data signals 72. This enables the control unit 64 to determine operating data signals 72 based on the operating data using a predefined communication protocol and to transmit these signals via the transmitter unit 68 and the signal coupler 104 to the first and second lines 22 and 24, which are connected to the terminal contacts 54 and 56. In this way, at least unidirectional communication similar to powerline communication can be achieved via the coupling module 20 over the lines 22 and 24.The filter circuit 58 serves here to decouple the buck converter 48 from the communication on lines 22, 24.

[0051] In the present embodiment, the switching element 114 is formed by two anti-series connected MOSFETs, which are switched simultaneously by means of the switching signal.

[0052] As will be explained below, the receiver unit 68 can also be used to implement bidirectional communication similar to powerline communication. However, in the present embodiment, only unidirectional communication is initially provided, similar to a unidirectional communication mode. According to the invention, this can be changed.

[0053] As from Fig. As can be seen in Figure 1, the photovoltaic system 10 also includes an operating status monitoring unit 26, which comprises a cloud server 28 and a communication interface 106 connected to the cloud server 28. Communication with the cloud server 28 can be wireless, for example via WLAN or similar technology, or wired. Data relating to the photovoltaic system 10, in particular the operating status of the photovoltaic system 10, can be accessed and made available via the cloud server 28.

[0054] In the present configuration, the Cloud Server 28 is designed separately from the operational data acquisition unit 26. However, alternative configurations may also provide for the operational data acquisition unit 26 to include the Cloud Server 28.

[0055] Out of Fig. It is further evident from Figure 1 that the Cloud Server 28 can communicate with a mobile terminal 30, which can be a user terminal. This can be done, for example, via a mobile network or another communication network, such as the Internet, combinations thereof, or the like.

[0056] Out of Fig. As can be seen from Figure 1, the mobile terminal 30 has an application 32 that makes it possible to retrieve data relating to the photovoltaic system 10, in particular the system's operating status, via the communication interface 106 and to signal this data using the mobile terminal 30. Furthermore, it is also possible to transmit control commands via the cloud server 28 and the communication interface 106 to the operational data acquisition unit 26 using the application 32 in order to activate one or more predefined functions or to retrieve specific data from the photovoltaic system 10.

[0057] Fig. Figure 3 shows a schematic block diagram of the operating state detection unit 26 according to Fig. 1. It can be seen that the operating status detection unit 26 has a corresponding detection communication unit 40 for each of the strands 34, 36, 38, which is connected to a corresponding signal coupler 44. In the present configuration, each signal coupler 44 is designed as a toroidal coupler and is connected to the respective line 24 of the strands 34, 36, 38. Thus, each detection communication unit 40 can receive and evaluate the operating data signals 72 of the coupling modules 20 assigned to this strand 34, 36, 38. The detection communication units 40 are essentially identical in this configuration.

[0058] For this purpose, the data acquisition communication units 40 have a receiver unit 110, which receives the operating data signals 72 and makes them available to the data acquisition communication unit 40 for initial evaluation by a control unit 112. The control unit 112 determines the operating data 84 of the respective photovoltaic modules 12 assigned to string 34, 36, 38 from the operating data signals 72. The determined operating data 84 is then transmitted via a communication link 46 to an evaluation unit 42 of the operating status acquisition unit 26, which in this case is provided by the cloud server 28. Based on the operating data 84, the evaluation unit 42 determines the operating status of the photovoltaic system 10. This operating status can be retrieved via the communication interface 106. The cloud server 28 stores the operating status for retrieval.

[0059] The evaluation unit 42 is connected via a communication link 46 to the control units 112 of the acquisition communication units 40, so that the evaluation unit 42 has access to the operating data of all photovoltaic modules 12 from all strings 34, 36, 38 in order to determine the system operating status. In alternative configurations, the control unit 112 can determine an operating status for the photovoltaic modules 12 connected to the respective string 34, 36, 38, which is then transmitted to the evaluation unit 42.

[0060] Thus, an entire operating state of the photovoltaic system 10 can be determined and provided.

[0061] Fig. Figure 4 shows a schematic signal representation of an operating data signal 72 of one of the coupling modules 20 according to Fig. 2. From Fig. As can be seen from Figure 4, the operating data signal 72 is a digital signal which, in the present embodiment, is transmitted via lines 16 and 18 using frequency shift keying according to a predefined communication protocol. In the present embodiment, the operating data signal 72 has a header 74 that identifies it as belonging to the predefined communication protocol. This enables the operating data acquisition unit 26, in particular the control unit 112, to identify the operating data signal 72 and its beginning. The present embodiment provides for block coding. The operating data signal 72 can consist of a data block as shown in Figure 4. Fig. 4 shown or consist of a plurality of data blocks, one of which is in Fig. Figure 4 shows that the data blocks may be retransmitted at predetermined times or under predetermined conditions.

[0062] Following the header 74 is a section containing signal data 76, which specifies, among other things, the size or data volume of the block. This is followed by a section 78 containing transmit address data that identifies the sender, namely the coupling module 20 transmitting the operating data signal 72. This is followed by a section 80 containing destination address data. In the present embodiment, the destination address data identifies the acquisition communication unit 40. This has the advantage of enabling secure and improved communication and ensuring reliable assignment of the operating data 84 on the acquisition side. If only a single strand 34, 36, 38 is present, the section 80 containing the destination address data can be omitted.

[0063] This is followed by section 82, which contains content data. This content data can, for example, specify the type of data, such as whether it is electrical power, electrical current, electrical voltage, and / or the like. Section 82 is then followed by section 84, which contains the operating data. Finally, section 86 follows with redundancy data to improve the reliability of the data transmission.

[0064] So far, it has only been discussed that in a unidirectional communication mode, operating data signals 72 are transmitted from the coupling modules 20 to the operating status acquisition unit 26. However, it has been shown that a plant operating status derived from this may not be sufficiently meaningful, because, for example, the acquisition of the operating data 84 by the coupling modules 20 occurs at different times.

[0065] This problem can now be solved by sending an activation signal 88 to the line 24 by means of a transmitter unit 108 of the acquisition communication unit 40 to activate bidirectional communication between the operating status acquisition unit 26 and the coupling modules 20. Fig. Figure 5 shows a schematic signal representation of the activation signal 88 of the operating state detection unit 26 according to Fig. 3.

[0066] As with the module communication unit 70, the receiver unit 110 of the acquisition communication units 40 is directly electrically connected to the signal coupler 44. In contrast, the transmitter unit 108 is not directly connected to the signal coupler 44. Instead, the transmitter unit 108 is connected to the signal coupler 44 via an electronic switching element 116. The switching state of the switching element 116 is controlled by a switching signal provided by the control unit 112. The control unit 112 switches the switching element 116 to the on state only when the transmitter unit 108 is operating in transmit mode. The control unit 112 provides the switching signal, among other things, depending on the fact that no other communication participants are active. Otherwise, the switching element 116 is in the off state.This allows a small impedance of the transmitter unit 108 to be deactivated during reception operation of the receiver unit 110, thereby improving the reception of signals, especially the operating data signals 72. Here too, the switching element 116 is provided for by two anti-series connected MOSFETs, which are switched simultaneously by means of the switching signal.

[0067] Out of Fig.As can be seen in Figure 5, the activation signal 88 is essentially configured like the operating data signal 72. The activation signal 88 also has a header 90, which can be configured essentially like the header 74. A section 92 containing signal data follows the header 90 and can be implemented according to section 76 of the operating data signal 72. This is followed by a section 94 containing transmit address data, in which address data of the respective acquisition communication unit 40 is specified. In the present embodiment, the activation signal 88 is a signal that is transmitted in the manner of broadcasting, so that each of the coupling modules 20 of the respective string 34, 36, 38 receives and processes this signal. A section 96 containing acquisition time data follows the section 94.The acquisition time data determines an acquisition time at which the coupling modules 20 are to acquire their respective operating data 84. Area 96 is followed by an area 98 containing redundancy data, which can essentially correspond to area 86 of the operating data signal 72.

[0068] The received activation signal 88 is processed by the respective control units 64 of the coupling modules 20, and the acquisition of the operating data 84 at the respective acquisition time is carried out. As soon as the operating data 84 is available at the acquisition times, the corresponding operating data signals 72 are determined and requested by the operating status acquisition unit 26. Thus, the operating status acquisition unit 26 has a data set of operating data 84 for all photovoltaic modules 12, from which a time-specific system operating status can then be determined. This further improves the reliability and informative value of the system operating status.

[0069] Furthermore, it is of course also possible that the operating data 84 may include data relating to a malfunction, a maintenance request, and / or the like. This data can also be evaluated and made available for retrieval by the operating status monitoring unit 26. In addition, warning messages or hazard messages can of course also be issued by the operating status monitoring unit 26, for example directly to the mobile communication device 30 or the like.

[0070] In alternative configurations, it may also be provided that the operating status detection unit 26 sends a further signal, for example a deactivation signal, to the coupling modules 20 or the like.

[0071] The description of the figures serves solely to explain the invention and is not intended to limit it.

Claims

[1] Photovoltaic system (10) with - at least two photovoltaic modules (12), wherein each of the at least two photovoltaic modules (12) has several photovoltaic cells which provide electrical energy under the influence of light, wherein the photovoltaic cells of each of the at least two photovoltaic modules (12) are electrically connected to each other, - a system connection unit (14) for providing the electrical energy supplied by the photovoltaic cells of the at least two photovoltaic modules (12) with a predefinable DC voltage, wherein the system connection unit (14) has at least one first system connection (16) for providing a positive electrical potential of the DC voltage and at least one second system connection (18) for providing a negative electrical potential of the DC voltage, - a respective coupling module (20) for each of the at least two photovoltaic modules (12), wherein the respective coupling module (20) is electrically connected to the respective photovoltaic module (12), wherein the coupling modules (20) are electrically coupled to the at least one first system connection (16) and to the at least one second system connection (18) for the purpose of providing the electrical energy supplied by the photovoltaic cells of the respective photovoltaic module (12), wherein the coupling modules (20) are configured to determine operating data (84) for at least one operating state of the respective connected photovoltaic module (12), - wherein each coupling module (20) has a first transmitting unit (66) and a first receiving unit (68) and is configured to determine operating data signals (72) according to a predefinable communication protocol depending on the operating data (84) and to transmit the operating data signals (72) at least to the first or at least to the second line (22, 24), and - an operating state detection unit (26) comprising a second transmitting unit (108) and a second receiving unit (110) which are signal-technically coupled to the at least one line (22, 24) to which the operating data signals (72) can be transmitted, wherein the operating state detection unit (26) is configured to receive and evaluate the operating data signals (72) transmitted by the coupling modules (20) in order to determine the operating data (84) and, depending on the operating data, to determine an operating state of the photovoltaic system (10), characterized by, that the respective transmitting unit (66, 108) and the respective receiving unit (68, 110) are coupled in parallel to the at least one line (22, 24) to which the operating data signals (72) can be transmitted, wherein the transmitting unit (66, 108) is coupled to the at least one line (22, 24) by means of a switching element (114, 116). [2] Photovoltaic system according to claim 1, characterized by , that the switching element (114, 116) is designed as an electromechanical switching element. [3] Photovoltaic system according to one of the preceding claims, characterized by , that the switching element (114, 116) is designed as an electronic switching element. [4] Photovoltaic system according to claim 3, characterized by that the electronic switching element has at least one transistor operating in switching mode. [5] Photovoltaic system according to claim 3 or 4, characterized bythat the electronic switching element has at least two transistors operated in switching mode, wherein the transistors are connected in antiparallel or antiseries configurations. [6] Photovoltaic system according to any of the preceding claims, characterized by , that the signal coupling of the respective transmitting unit (66, 108) and the respective receiving unit (68, 110) with the at least one line (22, 24) to which the operating data signals (72) can be output is carried out by means of a signal coupler (104) to which the receiving unit (68, 110) and the switching element (114, 116) are connected in parallel. [7] Photovoltaic system Claim 6, characterized by , that the signal coupler (104) is designed to provide galvanic isolation between the at least one line (22, 24) to which the operating data signals (72) can be transmitted, on the one hand, and the transmitting unit (66, 108) and the receiving unit (68, 110) on the other hand. [8] Method for operating a photovoltaic system (10) with at least two photovoltaic modules (12), wherein each of the at least two photovoltaic modules (12) has several photovoltaic cells which provide electrical energy when exposed to light, wherein the photovoltaic cells of each of the at least two photovoltaic modules (12) are electrically connected to each other, - wherein the electrical energy provided by the photovoltaic cells of the at least two photovoltaic modules is supplied with a predefinable DC voltage at a system connection unit (14) of the photovoltaic system (10), wherein the system connection unit (14) has at least a first system connection (16) for supplying a positive electrical potential of the DC voltage and at least a second system connection (18) for supplying a negative electrical potential of the DC voltage, - wherein the electrical energy provided by the photovoltaic cells of the respective photovoltaic module (12) is transmitted via a respective coupling module (20) of the photovoltaic system (10) electrically connected to the respective photovoltaic module (12) and via a first line (22) connected to the at least one first system connection (16) and a second line (24) connected to the at least one second system connection (18), wherein the first and the second lines (22, 24) are coupled to the coupling module (20), wherein the coupling modules (20) determine operating data (84) for at least one operating state of the respective connected photovoltaic module (12), - wherein each coupling module (20) has a first transmitting unit (66) and a first receiving unit (68) and determines operating data signals (72) according to a specified communication protocol depending on the operating data (84) and transmits the operating data signals (72) at least to the first or at least to the second line (22, 24), and - wherein an operating state detection unit (26) of the photovoltaic system (10) has a second transmitting unit (108) and a second receiving unit (110) which are signal-technically coupled to the at least one line (22, 24) to which the operating data signals (72) are transmitted, wherein the operating state detection unit (26) receives and evaluates the operating data signals (72) transmitted by the coupling modules (20) in order to determine the operating data (84) and, depending on the operating data (84), to determine an operating state of the photovoltaic system (10), characterized by , that the respective transmitting unit (66, 108) and the respective receiving unit (68, 110) are coupled in parallel with the at least one line (22, 24) to which the operating data signals (72) can be transmitted, wherein the transmitting unit (66, 108) is coupled with the at least one line (22, 24) depending on a switching state of a switching element (114, 116). [9] Method according to claim 8, characterized by , that the switching state of the switching element (114, 116) is set depending on a switching signal, the switching signal being provided, among other things, depending on the fact that no other communication participants are active.

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