t partly contradict each other (see Figure 1). Over time, the focus has shifted: economic efficiency has become a central aspect for the liberalisation of the electricity market. This development was initiated at the end of the last century with the EU directive concerning the internal market in electricity.1 Many motivating factors underlie this development; paragraph 4 of the directive provides an overview: Whereas establishment of the internal market in electricity is particularly important in order to increase efficiency in the product