The Power of Design: Product Innovation in Sustainable Energy Technologies

3.5 Small Wind Turbines

Paul Kühn

Fraunhofer Institute for Wind Energy and Energy System Technology IWES, Königstor 59, Germany

3.5.1 Introduction

In the last two decades, wind power utilization has emerged from a niche industry to an industrial sector with global significance. In the mid-1980s, wind turbines had an average rated power of 30 kW and rotor diameters of less than 15 m. Since then, wind turbines with a rated power of 5 MW and more and rotor diameters of more than 125 m have been developed. Today, multi-megawatt wind turbines of 2 MW and more dominate the market. But in the last few years the interest in small wind turbines has also grown again. Small wind turbines are used in a broad field of application ranging from very small mobile battery chargers rated at only a few hundred Watts to grid-connected systems with up to about 100 kW.

3.5.2 Turbine Size and Applications

Some useful parameters for small wind turbine classification are their physical size, that is, the rotor diameter or the rotor swept area as well as their electrical properties, usually the rated electrical power. According to the international standard for the design requirements, small wind turbines have a rotor swept area equal to or smaller than 200 m², generating at a voltage below 1000 V AC or 1500 V DC (IEC, 2006). This corresponds to a rotor diameter of up to 16 m and a rated power of up to about 75 kW. Furthermore, it is useful to distinguish between larger commercial systems and smaller residential ...