This study analyses the German electricity price mechanism and laws used for the calculation of electricity costs. The goal is to find which price components and regulatory to relief energy-intensive companies are affected by energy efficiency and/or by demand response measures in a German company. Therefore the price mechanism and laws were used in a newly self-developed open source tool to easily and quickly calculate electricity costs. Grid charges increase significantly if the power consumption is increased. Even short peaks in the load profile may prevent individual grid charges for a company, i.e. an increase in electricity costs for companies. This price mechanism makes a flexible power consumption economically unappealing.