Taking into account the expected growth in demand and the deployment of other forms of renewable energy the required wind capacity in 2020 is estimated to be between 3,500 and 3,800MW . The totalled installed capacity of wind turbines at the end of 2015 was 2,457 MW . Thus between 1,100 and 1,400MW of new wind capacity is required to reach the target.
Wind turbines have been getting bigger. Machines with rated capacity of 1.5MW to 3.5MW are now common in response to the favourable economics of manufacturing larger machines. The turbines are also getting taller to capture the greater power of the wind available at higher altitudes. Wind farms can, subject to planning, be of many different sizes and 12 to 24 turbines in a single farm would not be unusual.
Thus about 35 wind farms with twelve 3.5MW wind turbines would meet a requirement for 1,400MW.