Abstract: A protective device for a photovoltaic system includes at least one input for connection to a photovoltaic generator and at least one output for delivery of an electric power supplied from the photovoltaic generator. The protective device includes a detection device for a signal applied via the at least one output, and is configured to provide a low level-limited voltage at the at least one output if an applied signal does not meet a predetermined criteria, and is further configured to connect the at least one output with low resistance to the at least one input via a switching device if the applied signal meets the predetermined criteria.

Abstract: The invention relates to a photovoltaic system for feeding three-phase current to a power grid that includes several monophase or three-phase photovoltaic inverters that can be connected to the power grid at the output end and are each fitted with a disconnecting device at the output end. The system includes several photovoltaic generators that are connected to the input end of the photovoltaic inverters. A central control and monitoring unit is connected between the photovoltaic inverters and the power grid. The control and monitoring unit has a grid monitoring device at the feeding point to the grid to measure one or more grid parameters. At least one communication link is provided between the individual photovoltaic inverters or the individual disconnecting devices and the connected central control and monitoring unit such that the connecting devices can disconnect the individual photovoltaic inverters from the power grid by means of a control instruction signal of the communication link.

Abstract: A protection system configured to couple between a generator that has a number of partial strings and an inverter includes a control device, and a series-connection switching device configured to selectively connect the partial strings together in series. The system also includes a parallel-connection switching device configured to selectively connect the partial strings together in parallel, wherein the series-connection switching device is actuated by the control device such that it interrupts the series connection of the partial strings in case of a hazard, and the parallel-connection switching device is actuated by the control device such that it connects the partial strings together in parallel in case of a hazard.

Abstract: The invention relates an inverter that may be set up as part of a power generation system for the connection of a number of substrings, which, using DC switches, can be connected to each other in series into a string and with the inverter. The inverter includes a bridge circuit to transform the power generated by the string comprising series-connected substrings into a grid-compatible AC voltage and to feed the power into a grid. The inverter also includes a ground fault detector arranged on the AC side of the bridge circuit for ground fault monitoring of the string. A controller connected to the ground fault detector controls the DC switches so that in case of a ground fault, a complete decoupling of the connection of the string from the bridge circuit and a separation of the string into potential-free substrings is performed. A method of operating such a power generation system is also described.

Abstract: An inverter with galvanic separation including a resonant converter and an upstream mounted boost chopper is intended to provide galvanic separation in the context of a variable input and output voltage as it exists in photovoltaic systems, with the efficiency being intended to be optimized over the entire input voltage range. This is achieved in that a boost chopper or a buck chopper is mounted upstream of the resonant converter.

Abstract: A protective device for a photovoltaic system includes at least one input for connection to a photovoltaic generator and at least one output for delivery of an electric power supplied from the photovoltaic generator. The protective device includes a detection device for a signal applied via the at least one output, and is configured to provide a low level-limited voltage at the at least one output if an applied signal does not meet a predetermined criteria, and is further configured to connect the at least one output with low resistance to the at least one input via a switching device if the applied signal meets the predetermined criteria.

Abstract: A method of monitoring a plurality of strings of a photovoltaic system connected to a power inverter includes measuring current values from individual strings to the power inverter; determining a reference current value from the measured current values; and standardizing the measured current values to the reference current value. The method further includes and analyzing the standardized current values of individual strings within representative time periods by comparison with comparison values established for the individual strings. Based on the analysis a failure of an individual string is ascertained.

Abstract: A method of activating a Multi-String inverter for photovoltaic generators (1a, 1b) of a photovoltaic plant (6), the Multi-String inverter incorporating on the input side a separate DC-DC converter (2a, 2b) for each generator string (photovoltaic generator) (1a, 1b) and each output of the DC-DC converters (2a, 2b) being connected in parallel and to an input of a DC-AC converter (3) and the DC-AC converter (3) being connected with an alternating current mains (4) for feeding into the mains aims at improving efficiency. This is achieved in that one or several electrical variables, namely input current, input voltage and/or input power are measured at each DC-DC converter (2a, 2b) and at least one of the DC-DC converters (2a, 2b) changing its operating condition as a function of this measurement when a limit value and/or a range is exceeded in such a manner that its power loss is reduced so that the energy yield of the photovoltaic plant (6) is increased.

Abstract: The invention relates an inverter that may be set up as part of a power generation system for the connection of a number of substrings, which, using DC switches, can be connected to each other in series into a string and with the inverter. The inverter includes a bridge circuit to transform the power generated by the string comprising series-connected substrings into a grid-compatible AC voltage and to feed the power into a grid. The inverter also includes a ground fault detector arranged on the AC side of the bridge circuit for ground fault monitoring of the string. A controller connected to the ground fault detector controls the DC switches so that in case of a ground fault, a complete decoupling of the connection of the string from the bridge circuit and a separation of the string into potential-free substrings is performed. A method of operating such a power generation system is also described.

Abstract: An inverter has two input lines; an inverter bridge connected between the input lines and including at least one half-bridge having two normally conductive gate-controlled semiconductor switches; a controller which supplies control voltages to the gates of the semiconductor switches in an operative state of the inverter; and a DC voltage source for supplying an auxiliary control voltage to the gates of the semiconductor switches in an inoperative state of the inverter so as to hold the inverter bridge in a non-conductive state between the input lines. The DC voltage source has a charging unit connected between the input lines in series with a further normally conductive gate-controlled semiconductor switch, and charging a storage unit for electric charge, which is connected to the gate of the further semiconductor switch such that this switch becomes non-conductive, when the storage unit has been sufficiently charged for providing the auxiliary control voltage.

Abstract: The invention relates to a photovoltaic system for feeding three-phase current to a power grid that includes several monophase or three-phase photovoltaic inverters that can be connected to the power grid at the output end and are each fitted with a disconnecting device at the output end. The system includes several photovoltaic generators that are connected to the input end of the photovoltaic inverters. A central control and monitoring unit is connected between the photovoltaic inverters and the power grid. The control and monitoring unit has a grid monitoring device at the feeding point to the grid to measure one or more grid parameters. At least one communication link is provided between the individual photovoltaic inverters or the individual disconnecting devices and the connected central control and monitoring unit such that the connecting devices can disconnect the individual photovoltaic inverters from the power grid by means of a control instruction signal of the communication link.

Abstract: The subject matter of the invention is an inverter (1), comprising a casing (8) as well as at least one casing cover (2), said casing cover (2) being mechanically engaged with a safety plug (10), said safety plug (10) being in electrical connection with at least the one load-current circuit located on the DC side, the inverter being switched off or disconnected at least from the DC-side load-current circuit after removal of the safety plug from the casing (8).

Abstract: On an inverter (1) for converting an electric direct voltage, in particular of a photovoltaic direct voltage source into an alternating voltage with a direct voltage input with two terminals (DC+, DC?) and one alternating voltage output with two terminals (AC1, AC2) and with one bridge circuit including semiconductor switching elements (S1-S6), said bridge circuit comprising one first bridge branch (Z1) including four switching elements (S1-S4) and one second bridge branch (Z2) including two additional switching elements (S5, S6) as well as a freewheeling circuit provided with additional diodes (D7, D8), the efficiency is further increased without high frequency interferences and capacitive leakage currents having the possibility to occur on the generator side.

Abstract: The invention is directed to an inverter including a casing (1) with at least two chambers (2, 3), the one chamber (3) comprising the display (11) of a communication unit, said display (11) being pivotally disposed in the chamber (3).

Abstract: The subject matter of the present invention is a method for monitoring a photovoltaic generator (1) for generating current with a number of solar cells connected between two external connections by repeated feeding of a current with a frequency spectrum into the generator current circuit, detecting thereby a respective frequency response in the frequency spectrum with the supplied current as the input variable and an electric variable of the generator as the output variable, and detecting a change in the frequency response for monitoring the photovoltaic generator (1) in the event of a change during repeated feeding.

Abstract: An inverter comprises two input lines; an inverter bridge connected between the input lines and including at least one half-bridge comprising two normally conductive gate-controlled semiconductor switches; a controller which supplies control voltages to the gates of the semiconductor switches in an operative state of the inverter; and a DC voltage source for supplying an auxiliary control voltage to the gates of the semiconductor switches in an inoperative state of the inverter so as to hold the inverter bridge in a non-conductive state between the input lines. The DC voltage source has a charging unit connected between the input lines in series with a further normally conductive gate-controlled semiconductor switch, o and charging a storage unit for electric charge, which is connected to the gate of the further semiconductor switch such that this switch becomes non-conductive, when the storage unit has been sufficiently charged for providing the auxiliary control voltage.

Abstract: The subject matter of the invention is an inverter including a casing (1), said casing (1) including at least two casing chambers (2, 3) that are each closable through a separate cover (2a, 3a).

Abstract: A method of converting a direct voltage generated by a decentralized power supply system into three-phase alternating voltage by means of a plurality of single-phase inverters (WR1-WR3), said alternating voltage being provided for supplying an electric mains, is intended to avoid inadmissible load unbalances using single-phase inverters. This is achieved in that, upon failure of one inverter (WR1-WR3), an asymmetrical power supply distribution is reduced by limiting the output of the other inverters. The method makes it possible to simplify three-phase voltage monitoring.

Abstract: On an inverter (1) for converting an electric direct voltage, in particular of a photovoltaic direct voltage source into an alternating voltage with a direct voltage input with two terminals (DC+, DC?) and one alternating voltage output with two terminals (AC1, AC2) and with one bridge circuit including semiconductor switching elements (S1-S6), said bridge circuit comprising one first bridge branch (Z1) including four switching elements (S1-S4) and one second bridge branch (Z2) including two additional switching elements (S5, S6) as well as a freewheeling circuit provided with additional diodes (D7, D8), the efficiency is further increased without high frequency interferences and capacitive leakage currents having the possibility to occur on the generator side.