Renewable Energy World (April 1, 2013) reports:

By 2015 the global market for small and medium wind turbines (SMWT) is forecast to double, especially in developing and emerging markets, reaching U.S.$634 million. These technologies already have a track record of success in rural electrification projects. For instance, in China, SMWT started to be implemented in 1980, and by 2010 there were some 400,000 systems reported.

Turbines with a diameter of less than 15 meters and a power output below 50 kW are classified as small. However, most small wind turbines have a diameter of around 7 meters or less and a power output ranging between 1 kW and 10 kW. For very small installations, such as a remote household, wind turbines can have a diameter smaller than 2 meters and an output of 1 kW or less. Medium size wind turbines have a rotor diameter of 15-30 meters, and a maximum output of 50-250 kW. Read more.