Solar module, solar module-integrated arrangement and energy generation system

Abstract

Solar module (1), comprising: - a plurality of solar cells (8) connected together to generate a DC voltage power applied to module terminals, - a receiving unit (3) for receiving a precision time signal and - a communication unit (4) for transmitting the received precision time signal to an inverter (11) which is connected to the solar module (1) via DC lines (6), wherein the communication unit (4) is configured as a PLC unit for transmitting the precision time signal via the DC lines (6).

Description

[0001] The invention relates to a solar module with a receiving and a communication unit for transmitting the received precision time signal to an inverter, and to an energy generation plant with such a solar module.

[0002] With the growing share of decentralized, renewable energy generation in the electricity supply, there is an increasing need to influence the distribution of load flows in a power grid to prevent local grid overload. It is known that in inductive networks, a load flow through a network segment is accompanied by a phase shift in the grid voltage, so determining this phase shift allows conclusions to be drawn about the load on that segment.

[0003] Patent application DE 10 2017 112 438 A1 further discloses how to enable a network participant to control power exchange depending on the relative phase determined at the connection point, in order to contribute to regional load balancing of a network. For this purpose, the network participant has a receiving unit for receiving a time signal defining a reference time.

[0004] Document JP 2005 - 116 835 A further discloses an inverter with an integrated GPS module which extracts a time signal from the GPS signal and uses it to synchronize an AC voltage at the inverter output with an AC voltage generated by other, similar inverters.

[0005] Solar power systems, as decentralized energy generators with integrated measurement technology in the inverter, are particularly well-suited for monitoring load-flow-induced phase shifts and reacting quickly and appropriately to changes in these shifts. In such a system, it would be logical to also integrate the receiver for the reference time signal into the inverter.

[0006] However, this is countered by the fact that inverters are often installed in locations where a highly precise reference time signal, such as a GPS-based time signal, cannot be received. Therefore, the object of this invention is to ensure the reception of the highly precise time signal for solar power systems via a suitable configuration and to enable a low-effort implementation of the functionality for monitoring the phase shift of the grid.

[0007] This problem is solved by a solar module with the features of independent claim 1, a solar module-integrable arrangement with the features of independent claim 3, and an energy generation plant with the features of claim 4. Preferred embodiments of the invention are described in the dependent claims.

[0008] A solar module according to the invention comprises a plurality of solar cells connected to generate a DC voltage applied to the module terminals, a receiver unit for receiving a precision time signal, and a communication unit for transmitting the received precision time signal to an inverter connected to the solar module via DC lines. Integrating the receiver unit into the solar module ensures that a precision time signal is always available, since the solar module is installed outdoors for energy generation. Simultaneously, an operating voltage for the receiver unit and the communication unit can be easily generated via the module terminals or the DC lines, or even from the voltage drop across only a portion of the solar cells, thus ensuring that these components are powered by the DC voltage.

[0009] In an unclaimed embodiment, the communication unit is configured as a radio unit for wireless transmission of the precision time signal to the inverter. This avoids the additional effort of wired communication. The use of common radio protocols such as Bluetooth is possible without restrictions.

[0010] According to the invention, and without the need for additional wiring, the solar module is designed in which the communication unit is configured as a PLC (Power Line Communication) unit for transmitting the precision time signal via the DC lines already present for power transmission. In this case, the precision time signal can, for example, be capacitively or inductively modulated as a high-frequency signal onto the DC power and is thus transmitted, in particular, to an inverter intended for converting the DC power and evaluated there. However, other methods of superimposing a transmission signal onto the DC power are not excluded.

[0011] Naturally, the transmission of the precision time signal from the solar module to a connected inverter leads to a time shift, which is irrelevant in the context of monitoring a phase shift of the grid, as long as the time shift has a constant value over time.

[0012] In a further embodiment of the invention, a solar module-integrable arrangement comprises a receiver unit for receiving a precision time signal and a communication unit configured to transmit the received precision time signal to an inverter connected to the solar module via DC lines. The arrangement can be housed in a junction box of a solar module or have a separate enclosure for placement near the module, particularly between the DC lines by which the solar module can be electrically connected to other solar modules. In this way, the solar module-integrable arrangement can be electrically connected to the DC lines, particularly via insulation displacement connectors, to provide access to a supply voltage and, if necessary, to transmit the precision time signal.By using cutting and clamping technology, it is, for example, easy to retrofit an existing solar module or an existing energy generation plant with a solar module using an arrangement according to the invention.

[0013] In a further aspect of the invention, an energy generation plant comprises a solar module according to the invention and an inverter connected to the solar module, wherein the inverter has a device for detecting a point in time with a fixed phase reference within a voltage waveform of a connected network, in particular a voltage zero crossing, based on the precision time signal. In this way, the inverter can assign a specific point in time obtained from the precision time signal to each voltage zero crossing.

[0014] These individual time points can be aggregated, for example by averaging, to reduce the amount of data and compensate for fluctuations in the individual times due to grid distortions. The individual or aggregated time points can then be compared with zero-crossing times recorded at other points in the grid to detect and monitor any phase shift between these points over a longer period. For this purpose, the inverter is advantageously configured to store and transmit the recorded time point. Transmission can be achieved, for example, via a data connection to a portal using internet protocols.

[0015] The invention is illustrated below with the aid of figures, of which Fig. 1 an embodiment of a solar module and a solar module-integrable arrangement according to the invention; and Fig. Figure 2 shows an energy generation plant according to the invention.

[0016] In Fig. Figure 1 shows a solar module 1 in which a plurality of solar cells 8 are connected in series to generate DC power. The DC power is carried out of the solar module 1 via DC lines 6 to connect it to other solar modules or to an inverter. The DC lines 6 are routed through an arrangement 2, in particular an arrangement integrated into a junction box of the solar module. Within the arrangement 2, a communication unit 4 and a receiver 3 are connected to the DC lines 6 for electrical supply. Furthermore, an antenna 5 is connected to the receiver 3, via which the receiver 3 can receive a precision time signal, for example, a satellite-based GPS signal, from which a highly precise reference time can be obtained.The information about the reference time is transmitted to the communication unit 4 connected to the receiving unit 3. The communication unit 4 is configured to convert the reference time into a data signal of a suitable format and transmit it to an inverter. The data signal contains the reference time, and the format and signal frequency are selected such that the receiver can determine a reception time with sufficient accuracy, in particular an accuracy of less than 10 µs, preferably less than 1 µs. Suitable formats and usable frequency ranges are known to those skilled in the art.

[0017] The communication unit 4 can transmit the data wirelessly or via the DC lines 6 by modulating the data signal onto them, for example inductively or capacitively, as a high-frequency signal. The inverter can then demodulate and evaluate the data signal from the DC lines. With wireless transmission, inverters not connected to the solar module 1 via the DC lines 6 can also be supplied with the information about the reference time.

[0018] It should be noted that time delays occur along the entire transmission path of the precision time signal, caused by factors such as the length of the transmission path, signal generation, and signal processing. However, absolute synchronization with a reference clock is not required for the reference time to be usable; only relative synchronization is necessary. Therefore, constant time delays are not relevant here.

[0019] In Fig. Figure 2 shows an energy generation plant in the form of a building with a photovoltaic system installed on the roof, comprising solar modules 10. The solar modules 10 are connected to each other, to an array 2, and to an inverter 11 via direct current lines 6. The array 2 is shown here as a separate assembly but can be integrated into one of the solar modules 10, as described in the section on Fig.1 shown. The inverter 11 converts a direct current power supplied via the direct current lines 6 from the solar modules 10 into an alternating current power, which it supplies to a connected network 12, but also, if necessary, to loads 13 within the building.

[0020] The arrangement 2 is configured to receive a precision time signal from a time signal transmitter 14, in this case a satellite, and is located with its roof at a position where the precision time signal from the time signal transmitter 14 can be received. The arrangement 2 transmits the received time signal either as a radio signal or as a PLC signal modulated onto the DC power to the inverter 11, which is configured to receive it. Due to its installation location, for example in a basement of the building, the inverter 11 is not able to directly receive the precision time signal from the time signal transmitter 14.

[0021] Furthermore, the inverter is configured to detect a point in time with a fixed phase reference within a voltage waveform of the connected network 12, in particular a voltage zero crossing, to relate this point in time to the received time signal, and to store it. For this purpose, the inverter can incorporate a PLL (Phase Locked Loop) circuit. Instead of a single point in time with a fixed phase reference, a network frequency or a network frequency waveform with a start or end time related to the received time signal can also be determined and stored, so that a large number of detected points in time are reported, which increases the accuracy of the detection.

[0022] The data stored in this way about times and / or network frequencies or network frequency profiles can be transferred to a central evaluation unit for such data at a later time.

[0023] Since inverters already have a PLL circuit or another suitable circuit for determining a time with a fixed phase reference within a voltage curve of the connected network 12 for their operation, and regularly also have components for receiving the time signal for other communication purposes, an energy generation plant according to the invention can do without additional inverter-side components.

[0024] Arrangement 2 can also be retrofitted into an existing energy generation system. For this purpose, it can be installed in a junction box of an existing solar module and connected to the DC lines. However, it is also conceivable to provide an additional connection unit, in particular a connection unit that is simply clipped onto the DC lines using insulation displacement technology, as described in German patent application DE 20 2012 103 480 U1. Reference symbol list 1 solar module 2 Arrangement 3 receiver units 4 Communication unit 5 antenna 6 DC line 8 solar cells 10 solar modules 11 inverters 12 network 13 Last 14 Time signal transmitters

Claims

Solar module (1), comprising: - a plurality of solar cells (8) connected together to generate a DC voltage power applied to module terminals, - a receiving unit (3) for receiving a precision time signal and - a communication unit (4) for transmitting the received precision time signal to an inverter (11) connected to the solar module (1) via DC lines (6), wherein the communication unit (4) is configured as a PLC unit for transmitting the precision time signal via the DC lines (6). Solar module (1) according to claim 1, wherein the receiving unit (3) and the communication unit (4) are configured to be supplied from the DC voltage power. Solar module integrable arrangement (2) comprising a receiving unit (3) for receiving a precision time signal and a communication unit (4) set up for this purpose to transmit the received precision time signal to an inverter (11) which is connected to the solar module (1) via DC lines (6). Energy generation plant comprising a solar module (1) according to one of claims 1 to 2, and an inverter (11) connected to the solar module (1), wherein the inverter (11) has a device for detecting a time referenced to the precision time signal with a fixed phase reference within a voltage profile of a connected network (12), in particular a voltage zero crossing. Energy generation plant according to claim 4, wherein the inverter (11) is further configured to store and transmit the recorded time.

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