The figures for thermal plant take into account the mechanical availability of the plant as well as its particular operating characteristics. In the case of wind plant, the variability of wind means that capacity factors -- which depend on wind speed as well as turbine rating -- usually range between 15 and 45%. The discussion in this article is focused on the capacity factors achievable by wind turbines with 100% availability. In practice, well engineered wind turbines have availabilities well over 90% and this must be taken into account when data are required for performance assessments.
The term "load factor" is synonymous with capacity factor and the term "full load hours" which is also used frequently, particularly in Denmark and Germany, simply means the equivalent number of hours a plant would have to run at rated output in order to deliver the annual energy. This should not be confused with the number of hours that a wind turbine actually delivers rated power which is usually of the order of 10-15% of the total -- depending on the rating.