A method and an apparatus for dechucking an electrostatic chuck are disclosed. In a stereo signal converter, a correlation analyzer calculates the power of a left channel signal, the power of a right channel signal, and a correlation value using the left channel signal and the right channel signal. The sensor also has an evaluation circuit which is connected downstream of the sensor electrode and is intended to process a reception signal generated in the sensor electrode. An economic term of the global value function represents the value of the power flexibility to different energy players. Also disclosed is a wall element for such a rechargeable battery, and a battery housing.