Capacity Factors

Most renewable energy projects, like wind turbines, don't produce energy at their full capacity rating all the time.  "Capacity factor" is a term used to describe the percentage of power generated or predicted to be generated during a given period of time, relative to how much it would have generated during that period had it run at full power output.  For example, a wind turbine that runs half speed all the time, and a wind turbine that runs full speed half the time (and not at all the other half) would both have a capacity factor of 50%.  In a good wind area, a wind turbine will have a 30% to 40% capacity factor.