The electricity consumption of household customers is divided into three different categories.

•  The category "default contract" includes customers who are served by their regional default supplier and have not yet changed or switched their supply contract. For this evaluation, default contracts include energy supplied in the context of fallback supply (section 38 EnWG) and doubtful cases.
• The category "non-default contract with the default supplier" includes customers who are served by their regional default supplier but who have changed or adjusted their supply contract to their individual needs.
• The category "contract with a supplier other than the local default supplier" includes customers who purchase their electricity from a competitive supplier and have customised contract options.

An evaluation on the basis of these three categories makes it possible to draw conclusions about the importance of default supply and default suppliers since the liberalisation of the energy market.