A method for ascertaining whether an intermediate storage device is connected to a local electric power grid of a property is provided. A first energy meter is provided at a grid connection point between the local power grid and a public power distributing grid. A charging point for an electric vehicle is connected to the local power grid via a second energy meter. When an electric vehicle is connected to the charging point, a base output is measured by the first energy meter during a charging rest phase of the electric vehicle. A battery of the electric vehicle is charged using an output measured by the second energy meter and an output is measured by the first energy meter. A determination is made whether the charging output measured during the charging process corresponds to the difference between the output measured by the first energy meter and the base output.
