BESS Glossary

Fully integrated energy storage unit combining batteries, PCS, and thermal management in a single enclosure — AC power output, ready to connect.

Buying electricity when prices are low (charging) and selling when prices are high (discharging) to capture the price spread.

Adding new battery capacity to an existing BESS plant to compensate for degradation and maintain contracted performance.

Battery Energy Storage System — a large-scale installation that stores electrical energy in batteries and releases it to the grid on demand.

Battery Management System — monitors and protects battery cells by tracking voltage, temperature, current, and state of charge.

A BloombergNEF classification for energy storage manufacturers with proven bankability — based on project scale and customer diversity.

The degree to which a BESS project's equipment, contracts, and revenue projections are credible enough to secure financing.

Balance of Plant — all supporting infrastructure for a BESS site: civil works, cabling, cooling, switchgear, fencing, and grid connection.

The rate at which a battery charges or discharges relative to its capacity — 1C means full charge or discharge in one hour.

A market that pays BESS operators for having capacity available to deliver power when called upon — a readiness payment.

The process of testing and verifying a BESS plant before it enters commercial operation — the formal handover from EPC to owner.

Deliberately reducing or shutting off renewable energy generation because the grid cannot absorb the power — a key driver of BESS demand.

Pre-integrated containerized battery system with cells, BMS, thermal management, and DC protection — no PCS included.

The gradual loss of battery capacity and performance over time due to cycling and calendar aging.

Energy Management System — the software layer that optimises dispatch, scheduling, and energy trading for a BESS plant.

Engineering, Procurement, and Construction — the contractor responsible for designing, sourcing equipment, and building a BESS plant.

A grid service where BESS rapidly injects or absorbs power to maintain grid frequency at its target (50 Hz or 60 Hz).

The technical rules that a BESS plant must comply with to connect to and operate on the electricity grid.

Lithium Iron Phosphate — the dominant battery chemistry for grid-scale BESS, valued for safety, cycle life, and cost.

Nickel Manganese Cobalt — a lithium-ion chemistry with higher energy density than LFP, used in some BESS and widely in EVs.

Operations & Maintenance — the ongoing management of a BESS plant including monitoring, maintenance, and availability management.

Power Conversion System — converts DC power from the batteries to grid-compatible AC power, and vice versa.

A PCS integrated with a medium-voltage transformer on a shared skid — steps up voltage for grid connection in a single unit.

Route-to-Market provider — the company that connects a BESS plant to energy markets, executes trading, and optimises dispatch.

Combining multiple revenue streams — frequency regulation, arbitrage, capacity — to maximise a BESS plant's total income.

The percentage of energy recovered from a battery compared to the energy put in — typically 85–95% for lithium-ion BESS.

Site Acceptance Test — the formal test that verifies a BESS plant meets its performance specifications before handover to the owner.

State of Charge — the current energy level of a battery expressed as a percentage of its total usable capacity.

State of Health — a measure of a battery's remaining capacity relative to its original rated capacity, expressed as a percentage.

An uncontrolled, self-heating chain reaction in a battery cell that can lead to fire or explosion if not contained.