Photovoltaic power generation system, supply line for a power generation system, counterpart plug and inverter

Description

[0001] The invention relates to a photovoltaic energy generation system. Furthermore, the invention relates to a supply line for a photovoltaic energy generation system.

[0002] Photovoltaics is one of the key technologies in the energy transition, i.e., the shift away from fossil fuels to renewable energy sources. In a photovoltaic power generation system, sunlight is directly converted into electrical power in the form of direct current using solar modules in a solar generator. This is then converted into alternating current by an inverter for feeding into an alternating current grid. The resulting problem of supplying the inverter's electronics with the electrical power is typically solved by the inverter drawing its power supply preferentially from the alternating current grid or, if the inverter is disconnected from the grid, from the connected solar generator.However, since the voltage of the irradiated solar generator is significantly higher than the voltage required for the supply, a loss-inducing reduction of the solar generator voltage to the supply voltage is necessary. Furthermore, there are requirements for the operating states of the power generation system, in which not only the grid but also the solar generator must be disconnected from the inverter, or even the individual solar modules of the solar generator must be disconnected and / or short-circuited to ensure that voltage limits within the power generation system are not exceeded for reasons of personal safety. In this case, the option of supplying power from the solar generator is not available.

[0003] The document EP 2 267 860 A2 therefore proposes the use of an additional energy source to supply an inverter with separate connections to the grid and to the solar generator, which supplies the inverter with power from the grid.

[0004] Furthermore, DE 10 2010 017 746 A1 discloses a photovoltaic system with a number of substrings that are connected in series to the inverter during normal operation. In the event of an emergency, the series connection is disconnected to reduce the voltages occurring in the system below a critical value. In this case, the system can continue to operate on the grid by connecting the substrings in parallel to the inverter instead.

[0005] In light of the above-mentioned prior art, the object of this invention is to provide a photovoltaic energy generation system in which the inverter can be supplied with electrical power even when the inverter is disconnected from the grid and, for example, when strict voltage limits must be maintained by the solar generator due to regulatory requirements. It is also the object of this invention to provide a connecting cable or a connector system that enables a photovoltaic energy generation system to be powered by a voltage-limited solar generator.

[0006] This object is achieved by a photovoltaic energy generation system having the features of claim 1 and a supply line having the features of claim 9. Preferred embodiments of the invention are described in the dependent claims.

[0007] A photovoltaic energy generation system according to the invention comprising a string comprising a series connection of solar modules, which is electrically connected to an inverter via connecting cables for converting and feeding electrical power from the string into a grid, is characterized in that the inverter is configured to draw an alternative operating power from only one of the solar modules in the event that, upon disconnection of the inverter from the grid, normal operating power cannot be drawn from the grid or the entire string. The one of the solar modules that generates the alternative operating power is preferably located at one end of the series connection.

[0008] In a first embodiment, the alternative operating power is obtained from a voltage applied between the solar module terminals of one solar module. In this case, the entire power generated by the solar module is available as alternative operating power.

[0009] In a second embodiment, one of the solar modules has a sub-module connection that is electrically connected to an intermediate point between sub-modules of the one solar module, wherein the alternative operating power is obtained from a voltage applied between the sub-module connection and a solar module connection of the one solar module. As a result, only a portion of the electrical power generated by the solar module is available as alternative operating power, but the lower voltage makes this power easier to use as alternative operating power.

[0010] In a further embodiment that can be combined with the first and second embodiments, a DC / DC converter, in particular an output-voltage-regulated buck converter, is arranged between the one solar module and the inverter to convert the alternative operating power. The DC / DC converter converts the voltage provided by the solar module into a lower voltage value that can be directly used by inverters as alternative operating power. If the operating voltage required by the inverter is higher than the voltage provided by the solar module, a boost converter can also be used. Likewise, a boost / buck converter can of course also be used, which allows both an increase and a decrease in the solar module voltage.

[0011] The DC / DC converter is preferably also supplied by the power provided by the solar module and is advantageously only operated when the alternative operating power is required to operate the inverter.

[0012] The DC / DC converter can be placed as a standalone component of the power generation system near the solar modules or it can be integrated into the inverter.

[0013] According to the invention, the inverter has a further connection for receiving the alternative operating power together with a string connection via which one of the connecting cables is connected to the inverter. The further connection and the string connection of the inverter can be integrated in a common plug connection. To transmit the alternative operating power, a connecting cable is provided which is laid together with the connecting cables connected to the string connection. According to the invention, this connecting cable and the connecting cable connected to the string connection form a common supply line with a common outer insulation, which preferably has a plug at each end with separate plug contacts for the connecting cable and the connecting cable.

[0014] If the photovoltaic power generation system is configured to electrically isolate all solar modules in the string from one another and / or short-circuit all solar modules in the string (except for one solar module that provides the alternative operating power) upon disconnection from the grid and / or in the event of a hazard, alternative operating power can still be generated to supply the inverter from the one - non-short-circuited - solar module. This alternative operating power can then be used, for example, to restart the power generation system after the hazard has ceased, or to enable data communication with the power generation system at any time.

[0015] A further aspect of the invention relates to a supply line for a photovoltaic energy generation system with an inverter and a string of solar modules connected thereto in series. The supply line comprises a connecting line for transmitting a string current from the photovoltaic energy generation system to an inverter, a connecting line for transmitting an alternative operating power to the inverter, and an outer insulation surrounding the connecting line and the connecting line, which has an insulation strength with respect to a string voltage of the photovoltaic energy generation system.Male and female connectors are arranged at both ends of the supply line, each having a plug contact for the connecting line and a plug contact for the connecting line. The connecting line and the connecting line are preferably insulated from one another with an insulation strength that is lower than the insulation strength with respect to the string voltage of the photovoltaic energy generation system, and in particular corresponds to an insulation strength with respect to a solar module voltage. The connectors at both ends of the supply line are preferably plug-compatible with SunClix connectors. Such SunClix connectors are available, for example, from Phoenix Contact and have become established, particularly in the DC cabling of photovoltaic systems.The plug contact for the connected power corresponds to the plug contact of a conventional plug, while the plug contact for the connecting cable is arranged laterally with respect to the plug axis of the plug connection and is electrically connected to a corresponding mating plug contact of a mating connector when plugged in. For the purpose of contact protection, the plug contact and mating plug contact can each be housed in housing attachments made of insulating material. Transferring the modification described above to other connection systems commonly used in photovoltaics is conceivable and easily implemented.

[0016] A mating connector for a plug of such a supply line should also be mentioned here, whereby each plug contact of the plug is assigned a mating contact of the mating connector.

[0017] Such a mating connector can be used instead of a conventional, plug-compatible mating connector as part of an inverter to establish an electrical connection with a solar module in a photovoltaic power generation system. In particular, the mating connector can be permanently installed in a housing opening of the inverter. This allows the inverter to be supplied with an alternative operating power. However, such a supply can also be dispensed with by plugging a conventional plug into the mating connector according to the invention.

[0018] In the following, the invention is described in more detail with the aid of figures, of which Fig. 1 shows a first embodiment of an energy generation plant according to the invention, Fig. 2 shows another energy generation plant, Fig. 3 shows yet another energy generation plant, Fig. 4 shows an embodiment of a solar module for use in an energy generation plant according to the invention, Fig. 5 shows an embodiment of a plug of a supply line according to the invention, and Fig. 6 shows an embodiment of a plug of the Fig. 5 connector designed as a mating connector.

[0019] An energy generation system 1 according to the invention comprises an inverter 30 that can be connected to an AC voltage grid via a grid connection 40. On the DC side, the inverter 30 is electrically connected to a solar generator embodied as a string 20 via connecting cables 50. The connecting cables 50 are connected to string connections 51, 52 of the inverter 30. The string 20 is formed by a series connection of solar modules 10. One of the solar modules 10 is connected to one of the connecting cables 50 via a first solar module connection and to a second solar module connection via a connecting cable 60, as well as to further solar modules.The connecting line 60 is connected to the inverter 30 via a supply connection 61, so that the inverter 30 can optionally receive both the electrical power of the entire string 20 via the string connections 51, 52 and an alternative operating power generated solely by one of the solar modules 10 via one of the string connections 51 and the supply connection 61. For the provision of the alternative operating power, it is not important whether one of the solar modules 10 is electrically connected to the other solar modules of the string 20 or whether the other solar modules are generating any energy at all. Preferably, the connecting line 60 is laid together with one of the connecting lines 50, and both together form a supply line with shared external insulation.The insulation requirement of the connecting line 60 with respect to the one connecting line 50 does not require complex insulation, since the voltage between the two lines is determined by the voltage of the solar module 10 and is therefore, for example, too low to form an arc.

[0020] A further, not claimed embodiment of a photovoltaic energy generation system 1 is described in Fig. 2 shown. Here, instead of an additional connecting line, only an additional connection is provided between one of the solar modules 10, which is connected on one side to the inverter 30 by a connecting line 50, wherein the additional connection is made via a diode 70 to the other connecting line 50. This ensures that the inverter 30 can receive at least some of the power generated by one of the solar modules 10 of the string 20 via its string connections 51, 52, even if the other solar modules cannot provide any power via the supply lines because these are, for example, short-circuited or electrically separated from one another. On the other hand, the diode 70 prevents a current flow via this connection if the voltage of the string 20 applied to the connecting lines 50 exceeds the voltage of one of the solar modules 10.

[0021] The further, unclaimed embodiment of the Fig. 3 differs from the design of the Fig. 2 in that instead of a diode 70, a DC / DC converter 80 is now used. This can be designed as a boost converter or as a buck converter. The DC / DC converter 80 is preferably only operated when the string 20 is not providing any power via the connecting lines 50. In this case, the operation of the DC / DC converter 80 supplies the inverter 30 with alternative operating power via the string connections 51, 52. In an advantageous embodiment, the DC / DC converter is operated as an output voltage-regulated converter; particularly preferably, the DC / DC converter 80 is a buck converter that generates and provides the alternative operating power at a predetermined operating voltage, for example 5 V or 12 V, from the voltage of the one solar module 10. The supply power for the operation of the DC / DC converter 80 is preferably also taken from the one solar module 10.

[0022] Fig. 4 shows schematically how an energy generation system 1 can be constructed using connectors so that it can implement the inventive teaching, but at the same time largely corresponds to a conventional energy generation system. A solar module 10 is divided into three sub-modules 11, each with parallel-connected bypass diodes arranged between two solar module connections 12. In addition, the solar module 10 has a supply connection 13, which is connected to a connection point between two sub-modules 11. The solar module connections 12, as well as the supply connection 13, can be accommodated in a junction box of the solar module 10. In the case shown, additional solar modules 10, which together form a string 20, are represented by only one individual module for the sake of simplicity.

[0023] The solar module 10 is connected to a string connection 52 of the inverter 30 via a first connecting cable 50 and conventional SunClix connectors at a solar module connection 12. A second connecting cable 50 is connected to the second solar module connection 12, which, together with a connecting cable 60 connected to the supply connection 13, is led to a modified connector 90. The modified connector 90 is used in conjunction with Fig. 5 described in more detail and is connected to a modified mating connector 100, which is used in conjunction with Fig. 6 described in more detail. Starting from the modified mating connector 100, the connecting cable 50 and the connecting cable 60 run within a common external insulation 110 to a further modified connector 90, so that this connection forms a supply line for the energy generation system 1. The further modified connector 90 is then connected via a further modified mating connector 100 to a supply connection 61 and a string connection 51 of the inverter 30. In this way, the power generated by the corresponding sub-modules 11 of the solar module 10 is provided via the connections 12, 13, the cables 50, 60, and the plug connection via the modified connectors 90 and the modified mating connectors 100 at the connections 51, 61 and can be used as alternative operating power by the inverter 30.The string connection 51 and the supply connection 61 can be designed as a mating connector permanently mounted on the housing of the inverter 30, similar to the modified mating connector 100 (not shown). In this case, the modified connector 90 shown can be connected to the inverter 30 via a supply line, in which the connecting line 60 and the connecting line 50 are each provided with a modified connector 90 at one end and a modified mating connector 100 at the other end.

[0024] Fig. 5 shows further details of a modified connector 90, where Fig. 5a the modified connector 90 in a front view and Fig. 5b show the modified connector 90 in a side view. The modified connector 90 comprises a housing whose geometric dimensions correspond to the geometric dimensions of a conventional SunClix connector. A central contact structure 55, which can be connected to a connecting cable 50 and is designed to transmit the entire string current of a solar generator, also corresponds to the contact structure of a conventional SunClix connector. In addition, the modified connector 90 has a lateral attachment made of insulating material with a further contact structure 65, which can be connected to the connecting cable 60. The further contact structure 65 can be designed as a contact pin, and the attachment is preferably designed such that the contact structure 65 is arranged in a touch-safe manner inside the attachment.

[0025] Fig. 6 shows further details of a modified mating connector 100, where Fig. 6a the modified mating connector 100 in a front view and Fig. 6b show the modified mating connector 100 in a side view. The modified mating connector 100 comprises a housing whose geometric dimensions correspond to the geometric dimensions of a conventional SunClix mating connector. A central contact structure 55, which can be connected to a connecting cable 50 and is designed to transmit the entire string current of a solar generator, also corresponds to the contact structure of a conventional SunClix mating connector. In addition, the modified mating connector 100 has a lateral attachment made of insulating material with a further contact structure 65, which can be connected to the connecting cable 60. The further contact structure 65 can be designed as a contact sleeve, and the attachment is preferably designed such that the contact structure 65 is arranged in a touch-safe manner inside the attachment.Furthermore, the attachment of the modified mating connector 100 is designed such that it can be inserted into a modified connector 90 according to . Fig. 5 can be plugged in, and both the contact structures 55 and the contact structures 65 of the modified plug 90 are electrically connected to the contact structures 55 and the contact structures 65 of the modified mating plug 100. The contact structures 55, 65 are protected from contamination by the housings or attachments of the plug and the mating plug that are plugged into one another, for example by the attachments being plugged into one another.

[0026] Due to the lateral arrangement of the attachment, both the modified plug 90 and the modified mating plug 100 can still be plugged into conventional SunClix plugs or mating plugs. In this way, a conventional power generation system can be converted into a power generation system according to the invention by replacing the SunClix plugs and with minimal wiring effort. Exposed plug contacts, which arise when inserting conventional SunClix plugs into plugs or mating plugs according to the invention, can be protected from contamination and corrosion by sealing caps. List of reference symbols

[0027] 1 Energy generation system 10 Solar module 11 Sub-module 12 Solar module connection 13 Supply connection 20 String 30 Inverter 40 Grid connection 50 Connecting cable 51 String connection 52 String connection 55 Contact structure 60 Connecting cable 61 Supply connection 65 Contact structure 70 Diode 80 DC / DC converter 90 Connector 100 Mating connector 110 External insulation

Claims

1. A photovoltaic power generation system (1) with a string (20) comprising a series connection of solar modules (10), which is electrically connected to an inverter (30) via power lines (50) via string connections (51, 52) of the inverter (30) for converting and feeding electrical power from the string (20) into a network, characterised in that the inverter (30) is configured to obtain an alternative operating power from only one of the solar modules (10) in the event that normal operating power can be obtained neither from the network nor from the entire string (20), the one of the solar modules (10) being connected to a string connection (61) of the inverter (30) via a connecting line (60).

2. The photovoltaic power generation system (1) according to claim 1, wherein the one of the solar modules (10) is placed at one end of the series connection.

3. The photovoltaic power generation system (1) according to one of the preceding claims, wherein the one of the solar modules (10) has a submodule connection (13) which is electrically connected to an intermediate point between sub-modules (11) of the one solar module (10), wherein the alternative operating power is obtained from a voltage applied between the submodule connection (13) and a solar module connection (12) of the one solar module (10).

4. The photovoltaic power generation system (1) according to claim 1 or 2, wherein the alternative operating power is obtained from a voltage applied between solar module connections (12) of the one solar module (10).

5. The photovoltaic power generation system (1) according to one of the preceding claims, wherein the further connection (61) and the string connection (51) of the inverter are integrated in a common socket.

6. The photovoltaic power generation system (1) according to one of the preceding claims, wherein a connecting line (60) is provided for the transmission of the alternative operating power, which is installed together with the power lines (50) connected to the string connection (51).

7. The photovoltaic power generation system (1) according to claim 6, wherein the connecting line (60) and the power line (50) connected to the string connection (51) form a common supply line with a common external insulation, which at both ends has a connector (90) with respective plug contacts for the connecting line (60) and the power line (50).

8. The photovoltaic power generation system (1) according to one of the preceding claims, wherein the power generation system (1) is set up to electrically disconnect all solar modules (10) of the string (20) from one another and / or to short-circuit all solar modules except for one solar module (10) of the string (20) in the event of disconnection from the grid and / or in the event of danger.

9. A supply line for a photovoltaic energy generation system (1) with an inverter (30) and a string (20) connected thereto from a series connection of solar modules (10), comprising:- a power line (50) for transmitting a string current of the photovoltaic power generating system (1) to the inverter (30), - a connecting line (60) for transmitting an alternative operating power to the inverter (30), - an external insulation (110) which surrounds the power line (50) and the connecting line (60) and which has an insulation resistance to a string voltage of the photovoltaic power generating system (1), and - a male or female connector (90) at each of the two ends of the supply line, which each have a plug contact for the power line (50) and a plug contact for the connecting line (60), wherein the power line (50) and the connecting line (60) are insulated from one another with an insulation strength which is lower than the insulation strength with respect to the string voltage of the photovoltaic energy generation system (1), in particular corresponds to an insulation strength with respect to a solar module voltage, and wherein the plugs at both ends of the supply line are plug-compatible with SunClix connections.