Abstract: A method for determining a power reduction due to ageing of a photovoltaic module includes measuring a variable associated with a performance of the module in one or more time periods within a given year, each time period defining a class, and constructing curves of discrete values, each power curve constructed from the measured electric variable at a plurality of times of a day within each class, and the curves constructed for a plurality of years. The method includes determining energy values based on the constructed curves for at least one class for each of the plurality of years, and determining a power reduction of the photovoltaic module with respect to one or several previous years by calculating a difference between the energy output values of a given class in a particular year and the energy output values of the given class in a year previous to the particular year.

Abstract: A power generation system for feeding power from generators into an AC grid, the system comprising a plurality of inverters connected to corresponding ones of the generators, and connected to the AC grid is disclosed. The plurality of inverters forms part of a data network, wherein one of the inverters forms a communication unit for receiving feed-in parameters from a grid control system and for controlling the plurality of inverters via the data network such that the power generation system feeds power to the AC grid in accordance with the feed-in parameters.

Abstract: A method for determining a power reduction due to ageing of a photovoltaic module includes measuring a variable associated with a performance of the module in one or more time periods within a given year, each time period defining a class, and constructing curves of discrete values, each power curve constructed from the measured electric variable at a plurality of times of a day within each class, and the curves constructed for a plurality of years. The method includes determining energy values based on the constructed curves for at least one class for each of the plurality of years, and determining a power reduction of the photovoltaic module with respect to one or several previous years by calculating a difference between the energy output values of a given class in a particular year and the energy output values of the given class in a year previous to the particular year.

Abstract: A power generation system for feeding power from generators into an AC grid, the system comprising a plurality of inverters connected to corresponding ones of the generators, and connected to the AC grid is disclosed. The plurality of inverters forms part of a data network, wherein one of the inverters forms a communication unit for receiving feed-in parameters from a grid control system and for controlling the plurality of inverters via the data network such that the power generation system feeds power to the AC grid in accordance with the feed-in parameters.

Abstract: The invention is directed to an evaluation method for determining a power reduction due to ageing of at least one photovoltaic module at constant radiation intensity with a measurement of an electric variable that may change after a period of time such as cell current, cell voltage and/or cell power, without additional sensors for measuring the radiation intensity, with the following steps fixing at least one class k that can be compared year by year and within which a daily power curve or portions of the daily power curve of the photovoltaic module can be compared to each other due to the radiation intensity and the outside temperature to be expected as well as the radiation time, the class k corresponding to a defined period of a year, measuring energy output values Ek,n that can be compared year by year from a comparable power curve Pk,n (t) through the variable delivered by the photovoltaic generator so that energy differences are determined on the basis of the classes k, n being the respective year, i