Several options—e.g. one large or a greater number of smaller machines, the number of blades in a rotor, the type of generator, a gearless machine or one with gear box, upwind or downwind operation—are available when a decision on the specifications of a wind energy converter is taken. These different design options are compared in this chapter. A modern trend is to use large size horizontal axis upwind machines that usually have three blades and are with or without gear box. However, this decision is highly case specific depending upon the usage, wind profile, land availability, and other, similar factors.
Wagner, H. J., & Mathur, J. (2013). Design Considerations. In Green Energy and Technology (Vol. 0, pp. 45–60). Springer Verlag. https://doi.org/10.1007/978-3-642-32976-0_5