The thesis deals with methods of electricity pricing under various conditions. The goal was to develop new methods concerning the main theme and to create software tools for calculations. The main aim was pricing of new or enhanced electricity consumption. A method of determining the marginal cost is used. Development in the field of cost separation to the generation and distribution parts was made. The program MarNakl for calculation was created. The main part of the thesis deals with the economic evaluation of different variants of expansion and renewal of the electricity system. A new formula based on calculation of the average annual economic cost was derived and our personal contribution includes the formula adjustment to cover the tax...