Abstract: A circuit arrangement for setting a potential of a photovoltaic generator with respect to a ground potential (GND) includes at least one first resistance connected between a negative output of the photovoltaic generator and a ground connection, and a series circuit including at least one second resistance and a breakdown diode connected in series between a positive output of the photovoltaic generator and the ground connection to which the ground potential (GND) is applied. Alternatively, the circuit arrangement includes at least one first resistance connected between a positive output of the photovoltaic generator and a ground connection, and a series circuit including at least one second resistance and a breakdown diode connected in series between a negative output of the photovoltaic generator and the ground connection to which the ground potential (GND) is applied.

Abstract: A method for grid support by means of an inverter is disclosed, wherein the grid is supported by feeding in compensation currents. The method includes measuring a prevailing grid state, and breaking down voltages measured for measuring the prevailing grid state into symmetrical components of the grid state including positive sequence system components and negative sequence system components.

Abstract: A method of localizing stationary objects causing temporary shadowing of light sensitive components of a PV system is disclosed. The method includes analyzing an electrical signal of the light sensitive components with regard to an occurrence of a shadowing event caused by the stationary object, and determining from a solar altitude associated with the shadowing event a direction of the stationary object causing the shadowing event. The analysis of the electrical signal takes into account a shadow movement of the object as a function of the solar altitude. A distance of the object is determined from this analysis. The results of the method may be used to determine an energy loss associated with the stationary object and may support a decision on removal of the object to improve efficiency of the PV system.

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: The apparatus for monitoring a photovoltaic system includes an incoupling circuit configured to couple an AC voltage test signal into the photovoltaic system, and an outcoupling circuit configured to outcouple a response signal, which is associated with the test signal, from the photovoltaic system, and an evaluation device, which is connected to the outcoupling circuit. The evaluation device is configured to identify events which adversely affect correct operation of the photovoltaic system. The apparatus is distinguished in that the outcoupling circuit includes a first transformer and a second transformer, each having a respective primary winding and each having a respective secondary winding which is connected to the evaluation device, with the primary windings of the first and second transformers being arranged in different electrical lines between a generator and an inverter in the photovoltaic system. The disclosure also relates to a corresponding method for monitoring a photovoltaic system.

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: The invention relates to a process of connecting an AC output of a transformerless inverter of a solar power plant to an internal AC power grid at an input side of a galvanic isolation, while an offset voltage for shifting a potential center point of a photovoltaic generator connected to the inverter is applied. The process includes: (i) synchronizing the inverter with the power grid; (ii) essentially matching a potential center point of the current-carrying lines of the AC output and a potential center point of the power grid, while only one of the potential center points of the current-carrying lines and the power grid is yet shifted by the offset voltage; and (iii) galvanically connecting all current-carrying lines of the AC output with the power grid only after the steps of synchronizing and essentially matching.

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: A method for the operational control of an inverter designed for DC/AC voltage conversion that has at least one direct-voltage input and that can be connected to a power supply grid via at least one alternating-voltage output, the inverter being involved in a power flow interaction with the grid in such a manner that, during operation of the inverter, a leakage current IA can occur, wherein the leakage current IA is controlled in the operational control.

Abstract: A method for monitoring of contacts of a photovoltaic system includes injection of a test signal having a plurality of frequencies, into the photovoltaic system, and determining a generator impedance of the photovoltaic system by evaluating a response signal associated with the test signal. The method further includes monitoring of contacts of the photovoltaic system independently of operating states of the photovoltaic system by modelling of an alternating-current response of the photovoltaic system based on the determined generator impedance, wherein the modelling is specific to at least two different operating states of the photovoltaic system.

Abstract: A circuitry arrangement for a solar power plant includes a transformerless inverter for feeding electric power from at least one photovoltaic generator into an alternating power grid, a galvanic separation of all lines carrying current between the inverter and the power grid, and a DC voltage source in an offset path between one electric line at the input side of the galvanic separation and a reference potential. The DC voltage source provides an offset voltage. The offset path includes a DC branch and an AC branch connected in parallel. The direct voltage source is connected in series with a current sensor in the DC branch, and at least one capacitor is arranged in the AC branch. Further, a DC contactor triggered by the current sensor is arranged in the offset path.

Abstract: A method of communication of distributed devices handling electric energy with communication partners via the Internet includes programming rules in a server. The rules determine between which device and which communication partner a communication connection is to be mediated based on generic properties of the devices, generic properties of the communication partners and an initializing time-variable datum. The communication connection is a point to point, point to multi point or multi point to multi point connection via the internet. Data are transmitted from each device and each communication partner to the server via the Internet. These data include both a communication address and attributes indicative of the generic properties of the device or the communication partner, respectively. The communication connection is mediated between the device and the communication partner determined by the rules in response to a value of the initializing time-variable datum also defined by the rules.

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: An inverter operable to interface with a generator that has a number of partial strings includes an inverter bridge circuit configured to connect to the partial strings, and a control device operably associated with the inverter bridge circuit. The inverter further includes a series-connection switching device configured to selectively connect the partial strings in series in response to a control signal from the control device such that the series-connection switching device interrupts the series connection of the partial strings in case of a hazard condition detected by the control device.

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.