This paper presents the development of the Polish energy system in the context of the changes taking place in the energy systems of other European Union Member States. Power system development plans in selected European countries were analysed, as well as their impact on the development of the national energy system. To be effective, an energy policy must affect the investment decisions of business entities. Poland is at the time when it should create the optimal energy mix concept and consistently strive for its implementation. This paper aims to show the real direction of growth in the electricity generation assets in Poland, as well as to indicate the possible impact of trends in the policies of European Union Member States on the electricity market in Poland.