Resource adequacy (RA) assessments are carried out to identify the risk that a system’s supply resources are insufficient to meet forecasted demand. Capacity contribution, or capacity value, is used to represent the impact of a specific generation resource within an RA assessment. An emerging trend to include an energy storage component alongside solar or wind generators has given rise to the term “hybrid resource.” Both the energy-limited nature of energy storage and its combination with a variable renewable resource mean that the availability of hybrid resources is unlike that of any other type of resource currently modeled in RA studies.
This technical update focuses on identifying the capacity contribution or capacity value of combinations of solar or wind generators with colocated energy storage as hybrid resources. The study identifies the impact of several plant design factors on the ability of the system to meet load obligations. These include the dimensions of the storage plant, the operational mode, the coupling mechanism between the storage component and the plant, and changing net load profiles.
The research examined seven variations of these factors through a case study on a large balancing area system. Results indicated material variance between capacity values depending on plant configuration and operation, indicating the need for site-specific consideration in the RA process.