Summary of Time Period-Based and Other Approximation Methods for Determining the Capacity Value of Wind and Solar in the United States: September 2010 - February 2012

This paper updates previous work that describes time period-based and other approximation methods for estimating the capacity value of wind power and extends it to include solar power. The paper summarizes various methods presented in utility integrated resource plans, regional transmission organization methodologies, regional stakeholder initiatives, regulatory proceedings, and academic andindustry studies. Time period-based approximation methods typically measure the contribution of a wind or solar plant at the time of system peak--sometimes over a period of months or the average of multiple years.