Energy Storage Flashcards
7 cards from real NABCEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Energy Storage flashcards as text
An ESS is required to provide backup power for a 120V, 20A critical load circuit. What minimum continuous output current rating must the battery inverter provide?
Answer: 20A
The inverter must be rated to continuously supply at least the full 20A load; the 80% continuous load rule applies to overcurrent protection, not to inverter output ratings.
Which IFC/NFPA standard provides fire safety and installation requirements specifically for stationary storage battery systems?
Answer: NFPA 855
NFPA 855 is the Standard for the Installation of Stationary Energy Storage Systems, covering fire protection, separation distances, and ventilation requirements.
A battery-based system uses 'self-consumption' mode. Which operational strategy does this describe?
Answer: Using solar energy to charge the battery first, then powering loads from stored energy instead of exporting
Self-consumption mode prioritizes using solar energy on-site by storing excess generation in the battery and discharging it to serve loads, minimizing grid import and export.
What is the purpose of a 'state of health' (SoH) measurement in a battery management system?
Answer: To express the battery's present maximum capacity as a percentage of its original rated capacity
State of health compares the battery's current maximum capacity to its original rated capacity, expressing overall degradation as a percentage.
For a grid-tied battery storage system to provide backup power during a utility outage, it must include which critical feature?
Answer: A transfer switch or intentional islanding capability
A transfer switch or anti-islanding override capability is required to safely disconnect from the grid and form an island to power critical loads during an outage.
Which wiring method is typically required when installing battery cables in an ESS with lithium-ion batteries indoors?
Answer: Listed and labeled cables or conduit-wired conductors rated for the voltage and current
NEC 706 and manufacturer installation requirements specify that battery interconnections use listed cables or conductors in appropriate conduit rated for the system voltage and current.
What does a battery inverter's 'transfer time' specification indicate in a backup power application?
Answer: The time elapsed between a grid outage and when the inverter begins supplying backup power
Transfer time is the delay between detection of a grid outage and the battery inverter supplying power to the backup loads, typically measured in milliseconds to cycles.