Battery Storage Systems & Energy Storage Flashcards

In an AC-coupled battery storage system, the battery inverter connects to which bus?

Answer: The AC electrical panel or AC bus

In an AC-coupled system, the battery inverter connects to the AC bus, meaning solar energy is first inverted to AC before being re-converted to DC for battery charging.

Which NFPA standard specifically addresses the installation of stationary lead-acid and lithium-ion battery systems in commercial buildings?

Answer: NFPA 855

NFPA 855, Standard for the Installation of Stationary Energy Storage Systems, provides requirements for battery system placement, separation, fire suppression, and hazard mitigation.

What is 'cycle life' as applied to battery storage systems?

Answer: The number of complete charge/discharge cycles before capacity falls below a specified threshold

Cycle life is the number of full charge/discharge cycles a battery can undergo before its usable capacity degrades to a defined percentage (commonly 80%) of original rated capacity.

Which lithium battery chemistry is most susceptible to thermal runaway if overcharged or mechanically damaged?

Answer: Lithium nickel manganese cobalt oxide (NMC)

NMC (lithium nickel manganese cobalt oxide) chemistry has higher energy density but is more prone to thermal runaway compared to LFP, which has superior thermal and chemical stability.

What is the primary safety concern when installing flooded lead-acid batteries in an enclosed indoor space?

Answer: Hydrogen gas off-gassing during charging creating explosion risk

Flooded lead-acid batteries release hydrogen gas during charging, which is explosive at concentrations above 4% in air, requiring adequate ventilation per NEC and manufacturer requirements.

For a grid-tied battery storage system to provide backup power during a utility outage, it must include which feature?

Answer: An automatic transfer switch or islanding-capable inverter

Backup capability requires an automatic transfer switch (ATS) or an inverter with islanding capability to disconnect from the grid and power loads independently during an outage.

When sizing a battery system for a residential time-of-use (TOU) rate optimization application, what is the primary design driver?

Answer: Load during high-rate utility pricing periods

TOU optimization aims to store energy during low-rate periods and discharge during high-rate periods, so the battery must be sized to cover the critical loads during expensive on-peak hours.