This report supplements the report, “Protocol for Uniformly Measuring and Expressing the Performance of Energy Storage Systems,” PNNL-22010 Rev. 2 / SAND2016-3078 (2016 Protocol). It provides the background and documentation associated with the development of a duty cycle to be applied to an energy storage system (ESS) for any of the two applications (Frequency Regulation with VAr and Peak Shaving with VAr applications) for the purpose of measuring and expressing ESS performance in accordance with the 2016 Protocol for measuring and expressing ESS performance.