The National Electrical Manufacturers Association has adapted the Protocol for Uniformly Measuring and Expressing the Performance of Energy Storage (herein referred to as the Protocol) into a NEMA Standard.
As cited in the DOE OE ES Program Plan, “Industry requires specifications of standards for characterizing the performance of energy storage under grid conditions and for modeling behavior. Discussions with industry professionals indicate a significant need for standards ” [1, p. 30].
This report describes development of an effort to assess Battery Energy Storage System (BESS) performance that the U.S. Department of Energy (DOE) Federal Energy Management Program (FEMP) and others can employ to evaluate performance of deployed BESS or solar photovoltaic (PV) +BESS systems.
The energy storage capacity, E, is calculated using the efficiency calculated above to represent energy losses in the BESS itself. This is an approximation since actual battery efficiency will depend on operating parameters such as charge/discharge rate (Amps) and temperature.
Is energy storage a future power grid?
For the past decade, industry, utilities, regulators, and the U.S. Department of Energy (DOE) have viewed energy storage as an important element of future power grids, and that as technology matures and costs decline, adoption will increase.
What are the KPIs of a battery system?
For battery systems, Efficiency and Demonstrated Capacity are the KPIs that can be determined from the meter data. Efficiency is the sum of energy discharged from the battery divided by sum of energy charged into the battery (i.e., kWh in/kWh out).
What are the KPIs of a solar PV system?
The computer model used was the National Renewable Energy Laboratory's (NREL's) System Advisor Model (SAM). The KPIs reported are Availability (% up-time) and Performance Ratio (PR). If the PV system output was zero or less than 5% of the model estimate, then the time interval was counted as “unavailable.”