Abstract: A method for detecting a potential-induced degradation (PID) of PV modules of a PV installation includes operating a PV generator at a maximum power point (MPP), at a first generator voltage (U1) and first generator current (I1), and at a second generator voltage (U2) and second generator current (I2), where a first power (P1) at the first generator voltage (U1) is in a predefined first ratio V1=P1/PMPP and V1?1, with the power (PMPP) at the maximum power point (MPP) of the PV generator, and where a second power (P2) at the second generator voltage (U2) is in a predefined second ratio V2=P2/P1 and V2<1, with the first power (P1) of the PV generator, and where a quantity Y that characterizes a progress of the potential-induced degradation (PID) is determined from the values of the voltages (U1, U2) and/or the currents (I1, I2).

Abstract: A method for determining a currently maximum possible power of a photovoltaic (PV) installation operated in a curtailed manner and including a PV generator having at least one string, wherein the at least one string includes a series circuit of PV modules, in which at least one PV module is connected to adjacent PV modules in the string via a coupling circuit. The installation further includes an inverter which is connected, on the output side, to an energy supply grid and is connected, on the input side, to the PV generator. The installation also includes a controller for controlling the inverter and the coupling circuit, wherein the controller, in conjunction with the coupling circuit, is designed to vary a power drain of the PV module assigned to it relative to a power drain of the adjacent PV modules during operation of the PV installation.

Abstract: A method for determining a currently maximum possible power of a photovoltaic (PV) installation operated in a curtailed manner and including a PV generator having at least one string, wherein the at least one string comprises a series circuit of PV modules, in which at least one PV module is connected to adjacent PV modules in the string via a coupling circuit. The installation further includes an inverter which is connected, on the output side, to an energy supply grid and is connected, on the input side, to the PV generator. The installation also includes a controller for controlling the inverter and the coupling circuit, wherein the controller, in conjunction with the coupling circuit, is designed to vary a power drain of the PV module assigned to it relative to a power drain of the adjacent PV modules during operation of the PV installation.

Abstract: For determining the topology of a grid section of an AC power grid, the grid section comprising a grid connection point, at least one branch branching off from the grid connection point and including a plurality of energy consumption and/or energy generation units, and at least one measurement point in the at least one branch, dependencies of variations of a grid voltage measured at the at least one measurement point based on variations of connection power values of at least some individual ones of the energy consumption and/or energy generation units are determined.

Abstract: A method for detecting a potential-induced degradation (PID) of PV modules of a PV installation, having a measurement pass, includes operating a PV generator of the PV installation at a maximum power point (MPP) with values of generator voltage (UMPP) and generator current (IMPP) associated with the maximum power point (MPP), and operating the PV generator of the PV installation at a first generator voltage (U1) and detection of a first generator current (I1) associated with the first generator voltage (U1).

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 device and corresponding method for monitoring a photovoltaic system to detect an occurrence of events impairing normal operation of the photovoltaic system is provide. The photovoltaic system includes a photovoltaic generator including a first group of photovoltaic modules and a second group of photovoltaic modules being different from the first group. The device includes a first and a second pair of coupling means, both pairs including signal coupling-in means for coupling a test signal into the photovoltaic generator, and a signal coupling-out means for coupling out a response signal from the photovoltaic generator, the first pair of coupling means configured to selectively detect the occurrence of the events in the first group of photovoltaic modules, and the second pair of coupling means configured to selectively detect the occurrence of the events in the second group of photovoltaic modules.

Abstract: An inverter for feeding a grid-compatible AC voltage into a grid is described, wherein the inverter includes an inverter bridge for converting a DC voltage to a first AC voltage and a grid interface between the inverter bridge and the grid for converting the first AC voltage to the grid-compatible AC voltage for feeding into the grid. An AC interface via which an AC module for feeding into the grid can be connected, is arranged between the inverter bridge and the grid interface.

Abstract: For the purpose of determining a fault current component of a differential current which is measured as a current sum over a plurality of lines carrying a current of an AC current generator, an electric signal which depends on generator voltages present at the AC current generator with respect to earth potential and which is in phase with a leakage current component of the differential current is generated. The electric signal is scaled by multiplying it by a scaling factor; and the scaled electric signal is subtracted from the differential current to obtain a remainder. The scaling factor is repeatedly updated such that the effective value of the remainder reaches a minimum at the present value of the scaling factor.

Abstract: A method for determining a maximum power point (MPP) of a photovoltaic generator (PV) by variation of at least one parameter of search voltage and search current, within a maximally searchable search area on a power/voltage curve is disclosed. The method includes initializing by defining a start point with a start voltage and a start current, searching for the maximum power point (MPP) in at least one search direction by repeated variation of the search voltage or search current in the search area taking account of at least two limiting conditions for limiting the search area, wherein at least one of the limiting conditions for limiting the search area are is determined with evaluation of parameters provided in an operating state already attained during the search, and ending the search if one of the at least two limiting conditions for limiting the search area is met.

Abstract: For determining the topology of a grid section of an AC power grid, the grid section comprising a grid connection point, at least one branch branching off from the grid connection point and including a plurality of energy consumption and/or energy generation units, and at least one measurement point in the at least one branch, dependencies of variations of a grid voltage measured at the at least one measurement point based on variations of connection power values of at least some individual ones of the energy consumption and/or energy generation units are determined.

Abstract: A method for detecting an arc fault in a photovoltaic power circuit includes operating a photovoltaic generator at a first working point. A first signal related to a DC-current and/or a DC-voltage in the power circuit is determined. The first signal is analyzed and it is determined whether the signal indicates the presence of an electric arc in the power circuit. If so, the photovoltaic generator is operated at a second working point and a second signal related to the DC-current and/or the DC-voltage is determined. The first and second signals are then compared; and the occurrence of an arc fault in the power circuit is selectively signaled based on the comparison.

Abstract: A method includes searching for a point of maximum power based on a systematic load variation, setting the point of maximum power as the operating point of the photovoltaic generator, and tracking the operating point based on a load variation with a narrow variation range. The method also includes analyzing operating variables of the photovoltaic generator to determine the level of probability that the operating point deviates from the point of maximum power, selectively interrupting the tracking and carrying out another search to determine the point of maximum power as a function of the analysis of the operating variables, and setting the point of maximum power as the operating point, and resuming the tracking. The method further takes into account previous searches carried out in the presence of comparable operating variables to determine the probability.

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: A method for detecting an arc fault in a photovoltaic power circuit includes operating a photovoltaic generator at a first working point. A first signal related to a DC-current and/or a DC-voltage in the power circuit is determined. The first signal is analyzed and it is determined whether the signal indicates the presence of an electric arc in the power circuit. If so, the photovoltaic generator is operated at a second working point and a second signal related to the DC-current and/or the DC-voltage is determined. The first and second signals are then compared; and the occurrence of an arc fault in the power circuit is selectively signaled based on the comparison.

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: For the purpose of determining a stray capacitance of an AC current generator a differential current is measured as a current sum over a plurality of lines carrying a current of the AC current generator, an electric signal which depends on generator voltages present at the AC current generator with respect to earth potential and which is in phase with a leakage current component of the differential current is generated. The electric signal is scaled by multiplying it by a scaling factor; and the scaled electric signal is subtracted from the differential current to obtain a remainder. The scaling factor is repeatedly updated such that the effective value of the remainder reaches a minimum at the present value of the scaling factor.

Abstract: A method for determining a maximum power point (MPP) of a photovoltaic generator (PV) by variation of at least one parameter of search voltage and search current, within a maximally searchable search area on a power/voltage curve is disclosed. The method includes initializing by defining a start point with a start voltage and a start current, searching for the maximum power point (MPP) in at least one search direction by repeated variation of the search voltage or search current in the search area taking account of at least two limiting conditions for limiting the search area, wherein at least one of the limiting conditions for limiting the search area are is determined with evaluation of parameters provided in an operating state already attained during the search, and ending the search if one of the at least two limiting conditions for limiting the search area is met.

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 matching the power of a photovoltaic system producing electric energy by which a working point at which the system produces maximum power is set by changing the working point in an MPP matching process and by comparing the system power, which changes as a result thereof, is intended to be suited both for stationary characteristic curves and for non stationary generator characteristic curves and to be easy to carry out so that the best working point is always set, even when the system is subjected to external interfering factors. This is achieved in that one or several additional control steps or control cycles are performed in order to track during the matching process a power point changing under external impact for a working point of even higher power to be set.