Abstract : The installed capacity of wind power in Brazil and in the world is increasingevery year and, procedures are necessary for verifying the energy production of wind farms. Because of the high cost of investment, is not always possible to have a meteorological mast in the wind farm and, therefore, to measure according to IEC 61400-12-1 standards. Beberibewind farm has only one mast for 32 wind turbines, so this work evaluatesthe application of a nacelle wind speed transfer function in thecalculation of annual energy production and the capacity factor of windfarm. The influence of wind speed and direction in power productionwas explored. Wind speed and power production data were comparedwith WAsP software outputs. Some wind turbines had low productionwhen compared with others, because of the wakes of neighboring windturbines. New layouts were explored to obtain the same or higher annualenergy production a lower number of turbines. The percentage of wake effects was reduced from 7.1% to 1.8% using new layout.