The report describes the design criteria for high efficiency small-scale wind turbines. While the overall wind to electrical conversion efficiency for large diameter rotors can be set at around 50%, the design of conventional wind turbines with diameters below 0,5 m is limited by air turbulence and low electrical efficiency. Coupling a ring shaped generator with ducted blades an overall efficiency of the order of 32% for a diameter of 200 mm is feasible. This together with low friction bearings allows a starting operation at wind speeds of 1m/s.