Energy analysis of energy systems is a method to find the energy investment needed to install, operate, and maintain systems for energy supply. The results of such an analysis indicate the energy intensity, energy payback, and energy yield. Renewable energy technologies don't require much energy for their utilization but may require considerable energy for the erection or disposal of a facility. Wind energy converters, photovoltaic systems, and solar water heating systems have been analyzed, and energy yield ratios up to 75.89 have been found for wind energy systems, 7.14 for solar water heating systems, and 2.72 for photovoltaic systems. These values are an indication of the technical feasibility of these systems. The figures also suggest that the wind energy converters are the most attractive systems, followed by solar water heating and photovoltaic systems, respectively.