Abstract: A photovoltaic system having a photovoltaic generator, whose strings with series-connected photovoltaic modules have a positive pole and a negative pole, and with an inverter whose DC input is connected to the two poles. The voltage of the positive pole and/or of the negative pole is measured with respect to ground, and a first switching element located between the positive pole and the DC input of the inverter and/or a second switching element located between the negative pole and the DC input of the inverter is opened, while a third switching element located between the positive pole and the negative pole is closed, when the voltage of the positive pole or of the negative pole exceeds a predefined first or second limit value.

Abstract: A photovoltaic system comprises a plurality of photovoltaic modules which are electrically connected to a string or to multiple parallel-connected strings and form a PV generator. The first string end forms the negative pole of the photovoltaic generator, and the second string end forms the positive pole. A voltage reduction device is provided with the aid of which the potential of the negative pole is lowered to ground. Advantages with regard to the insulation class of the connecting cable used are also provided.

Abstract: A method for checking the operation of a photovoltaic module of a photovoltaic power station. The module has a positive terminal, a negative terminal and a number of solar cells, in particular thin-layer solar cells. An electric field emitted by the photovoltaic module as a result of solar radiation is measured at an exposed measurement location during the operation of the power station and the electrical voltage present between the positive terminal and the negative terminal is determined from the measured electric field. A corresponding measuring instrument has a sensor to be placed near the photovoltaic module so as to measure the electric field strength. A rod or wand may be used to position the sensor, or a robot may be configured for automatic travel on the photovoltaic module.

Abstract: A method for storing energy using a combined heat and pressure storage device, includes mixing a gaseous first component and a liquid second component in an initial first step at a first pressure/temperature point to form a working medium. The working medium is compressed in a following step in such a way that the working medium has a second pressure/temperature point, at which the second component is at least partially gaseous. The compressed working medium is led into the combined heat and pressure storage device and stored there. In order to recover the energy, the working medium is expanded, whereupon the second component is at least partially liquefied. An apparatus for implementing the method is also provided.

Abstract: A method and a device for carrying out the method are disclosed in order to aid in the search for faulty photovoltaic modules. In a photovoltaic system comprising multiple PV units electrically connected in parallel, each PV unit is assigned its own fixed current sensor. Furthermore, each PV unit can be removed from the parallel circuit by a switching device.

Abstract: The disclosure relates to a method for operation of a photovoltaic installation for feeding electrical power into a medium-voltage power supply grid, with the photovoltaic installation having a plurality of photovoltaic modules, at least one inverter and at least one medium-voltage transformer, and with the primary side of the medium-voltage transformer being connected directly to an alternating-current (AC) low-voltage output of the inverter, and at least one direct-current (DC) switching member being arranged between the photovoltaic modules and a DC input of the inverter. When the electrical power produced by the photovoltaic modules in the photovoltaic installation is not sufficient for feeding electrical power into the supply grid, the photovoltaic modules are disconnected from an inverter on the DC voltage side while, in contrast, the inverter remains connected to the medium-voltage power supply grid on the AC voltage side by the medium-voltage transformer.

Abstract: A measuring method for determining an output drop of a PV unit is provided. The PV unit is arranged within a photovoltaic system comprising a plurality of electrically parallel-connected PV units. Each PV unit can be removed from the parallel circuit by a switching device. Further, a total current measuring device for measuring the total current through all PV units of the parallel circuit is provided. The defective PV unit is determined in an evaluation unit by the connection and disconnection of a disconnect switch.

Abstract: In a method for forecasting shadowing of a photovoltaic (PV) system due to cloud formation or movement, part of the firmament is imaged with fisheye optics onto the input optics of a digital camera. Pixel groups associated with luminous intensity ranges are formed. The spatial arrangement of the groups is analyzed to forecast shadowing of a photovoltaic system. A line extending from the PV system to the sun is formed and is continuously tracked. A reference line located inside a region around the line is formed. Passage of clouds across a reference line is analyzed. The result of the analysis is used to increase the electric power from the PV system to a minimum value through supply of additional backup energy or to reduce the electric power consumption by disconnecting users to ensure that key users do not experience a drop in supplied power below a minimum value.

Abstract: An arrangement with a photovoltaic generator is provided that can be connected to the input of a power inverter, the output of which is connected to a supply network. The arrangement further comprises an asynchronous machine parallel to the output of the power inverter, which asynchronous machine is driven by an internal combustion engine.

Abstract: A photovoltaic system includes an inverter, a photovoltaic generator with a plurality of serially connected photovoltaic modules, said photovoltaic generator connected to the inverter by an electrical supply line, a controllable fuse interconnected in the electrical supply line between the inverter and the photovoltaic generator and having a signal input, and a voltage-dependent resistor connected between the signal input of the controllable fuse and the electrical supply line and generating a control signal which triggers the controllable fuse responsive to the control signal and interrupts the electrical supply line. The controllable fuse can be used to disconnect the electrical connection of the photovoltaic system to the inverter when a switch short-circuiting one or more modules of the photovoltaic generator malfunctions. The arrangement permits operation of photovoltaic system at an operating voltage of close to 1000 V, thereby allowing use of thinner cables.

Abstract: A meter for recording or determining the electrical energy withdrawn from an electrical supply network or supplied to it is provided. The meter including a component for measuring the current supply voltage, and a component for determining the operating mode based on the currently withdrawn or supplied electrical energy, wherein the operating mode can be changed, depending on the measured supply voltage, in such a way that a relatively high supply voltage causes a slower metering process than a comparatively low supply voltage.

Abstract: A photovoltaic system having a photovoltaic generator, whose strings with series-connected photovoltaic modules have a positive pole and a negative pole, and with an inverter whose DC input is connected to the two poles. The voltage of the positive pole and/or of the negative pole is measured with respect to ground, and a first switching element located between the positive pole and the DC input of the inverter and/or a second switching element located between the negative pole and the DC input of the inverter is opened, while a third switching element located between the positive pole and the negative pole is closed, when the voltage of the positive pole or of the negative pole exceeds a predefined first or second limit value.

Abstract: For network stabilization of an electric power supply network, the voltage at a first network connection point at a first voltage level to a power generator, and at a second network connection point to a second voltage level, as well as at at least one third network connection point to a load, are each sensed as a voltage measurement, wherein a reactive power draw or a reactive power delivery by the power generator is ascertained using a linkage of the voltage measurements with the geographic location of the relevant network connection point.

Abstract: A photovoltaic system having a plurality of photovoltaic modules producing electric energy and method for operating such photovoltaic system are disclosed. With the method, the photovoltaic modules are connected to a first DC motor having a motor shaft, and a generator shaft of a three-phase generator is coupled to the motor shaft. The three-phase generator can be connected to a power grid. The motor shaft of a second DC motor can be connected to the generator shaft, with only one of the two DC motors being initially driven with the electric energy produced by the photovoltaic modules. The electric energy is subsequently divided among both the first and the second DC motor. This process significantly shortens the startup process of the photovoltaic system compared to conventional systems.

Abstract: A mounting support for mounting photovoltaic modules constructed with at least one glass pane on a flat roof surface includes a flexible elongated strip having a bottom side with a substantially smooth surface for attachment to the roof surface and a top side with a substantially smooth surface for supporting the photovoltaic modules. The top side of the strip includes recesses oriented perpendicular to the longitudinal direction of the strip and separating strip segments which allows the mounting support or strip to be easily rolled up. The strip segments include integrally formed fastening members configured to engage with cooperating fasteners for securing the photovoltaic modules on top side of the strip. The top surface may also include longitudinal grooves or tubes holding the fastening members.

Abstract: During operation of at least one power generator (EE) in a power supply network, a reactive power transfer between the two upper voltage levels (1, 2) is sensed at a first transformer (T1) connecting these levels, and the voltage at a first network connection point (5) at the lowest voltage level (3) is ascertained. The amount of a reactive power demand served by the power generator (EE) is calculated as a function of the ascertained voltage value in order to maintain the voltage ascertained at the lowest voltage level (3) within a predefinable voltage range, wherein a means (WR) of the power generator (EE) is activated for a reactive power draw or a reactive power delivery, based on the calculated reactive power demand.

Abstract: A base frame for a parking lot roof equipped with photovoltaic modules is proposed, wherein two mirror-symmetrically constructed halves are provided, with each half having an inner arc constructed of three inner struts and an outer arc constructed of three outer struts, which are connected with each other by cross struts. The structure is light-weight and can be easily manufactured.

Abstract: A method for operating a photovoltaic system with a plurality of photovoltaic modules and with a DC motor connected to the photovoltaic modules is proposed. The motor shaft of the DC motor is coupled to a generator shaft of a three-phase generator, wherein the three-phase generator can be connected to a power grid. The motor shaft of a second DC motor can also be connected with the generator shaft, and the electric energy produced by the photovoltaic modules is initially only used for driving a single DC motor and is during the subsequent operation divided between those DC motors. A battery is provided which can be connected with the second DC motor instead of the PV system by changing the excitation of the second DC motor such that it's motor voltage corresponds to the open-circuit voltage of the battery.

Abstract: A method for operating a first energy generator in an electric power supply system to which a plurality of electric consumers and at least the first energy generator, which is embodied as a regenerative energy generator, are connected via respectively one grid connection point each assigned thereto, wherein at least the first energy generator has an inverter of predetermined power rating, the AC voltage output of which is electrically connected to a first grid connection point assigned thereto, and wherein the operating control of the inverter regarding its reactive power feed and/or its reactive power draw into or out of the electric power supply system takes place depending on a continuously measured mains voltage value. The reactive power control in the energy grid is improved in that the mains voltage value is measured at a second grid connection point, which is different from the first grid connection point of the energy generator.

Abstract: The photovoltaic system includes a plurality of photovoltaic modules which are connected to form a string or several strings connected in parallel, thereby forming a photovoltaic generator having a positive terminal and negative terminal. A DC constant voltage source connected to the photovoltaic generator to raise the potential of the positive terminal relative to ground potential. This reduces the flow of electrons out of the TCO layer of the modules, thereby reducing or completely eliminating cathode discharges which damage the modules.