BSWT is a vertical wind turbine based on sailing engineering. The wind rotor is rotated by two spiral-formed vanes. For best performance, these vanes are covered in solar cells, so that sun and wind produce electricity as one element. The BSWT installation costs relatively little, produces no noise or significant shadowing, can be easily maintained from ground level, and is an attractive addition to any home.
from the Bluenergy AG website.