This final thesis investigates the possibilities, procedures and rules for connecting the end customer of electricity to the distribution and transmission network. The methods of determining and the amounts of connection fees, the price of electricity and the possibilities of savings are analyzed. Legislative, technical and economic aspects and potential benefits for customers that would change the voltage level of the connection by changing the existing connection to the distribution network with a new connection to the transmission network were investigated. On specific example of end customer described techno-economic criteria and carried out the procedure of techno-economic evaluation of changes grid connection voltage level, as well as the analysis of sensitivity to changes in input parameters. After the defined criteria and calculated indicators, it is possible to make a better decision on investing in changing of end customer grid connection voltage level. In addition, the payback period was graphically calculated, depending on the type and length of the connection and the planned annual electricity consumption for the four characteristic types of connection. Although the payback period is only one of the evaluation criteria, the above input data can be used to easily assess the justification for changing the connection voltage level according to the payback period criterion. This final thesis confirms the hypothesis that the end customers connected to the distribution network, who are developing and planning to increase the need for electricity, have a justifiable reason to carry out techno-economic evaluation of the change of grid connection voltage level. Depending on the electricity consumption, location and conditions in the transmission network, it is possible to save on electricity costs and thus improve the competitiveness and market position of the end customer in the business in which he is engaged and for which he needs electricity.