For the past few years, renewable energy sources have been in a state of dynamic growth. With regard to all the green energy branches, wind turbines have experienced the fastest expansion in Poland as well as in the other parts of Europe. At the moment, a particular focus is paid to small wind turbine technology, targeted at both individual and private users. Even with a large number of new investments, there is still a noticeable sense of general public mistrust in wind energy. It is mainly due to the marketing policies of manufacturers, who do not inform of the realistic possible energy output of the proposed design, as well as of the environmental and technological factors that influence the efficiency of wind turbines. The purpose of this paper is to formulate and describe briefly the most important parameters that influence the efficiency and power output of a small wind turbine.