Energy-production performance is one of the most frequently analyzed parameters by wind-power site operators. Carrying out performance assessments is not usually a technical challenge for so-called conventional sites. However, the complex nature of winds and their interaction with turbines does make it difficult to assess wind-power performance. To date, only standard CEI 61400-12-1, which assesses performance for a single turbine at a time, is accepted industry-wide. In addition, it is a relatively onerous method.