The vocabulary of storage.

Glossary

The terms, in alphabetical order.

A

aFRR

automatic frequency restoration reserve

The second line of frequency reserve, called réserve secondaire in France. The transmission system operator (RTE) activates it automatically, to bring the frequency back to its setpoint after a deviation and to free the frequency containment reserve (FCR) to act again.

The value stack

Aggregation

Combining several sites through a third party, so as to reach the power thresholds that the market mechanisms require. A single site usually stays below those thresholds: aggregation is its gateway to those mechanisms and to the revenue they offer.

Arbitrage

Charging the battery when electricity is cheap and discharging it when electricity is expensive. The value depends on the spread between those two moments, which changes every day.

B

Balance responsible party

The party (BRP) that commits financially to balancing the injections and withdrawals within its balance perimeter. Taking part in the market mechanisms requires designating a balance responsible party for the site concerned.

BESS

Battery energy storage system

A battery storage system taken as a whole: cells, power conversion, protection devices, thermal management and control. The term covers the system as installed and operated, not the battery alone.

C

Capacity mechanism

The scheme that pays for the ability to be available when the grid is under stress, regardless of the energy actually exchanged. It pays for a promise of availability, not for a delivery.

The value stack

CRE

Commission de régulation de l’énergie

The French energy regulator. Its decisions, called deliberations, set TURPE, the French tariff for the use of the public electricity networks, and approve the rules of the market mechanisms that RTE operates – among them NEBCO, RTE’s demand response mechanism.

D

Demand response

The voluntary, temporary reduction of a site’s consumption, compared with what it would otherwise have been. On the market mechanisms, that reduction is what earns revenue; a behind-the-meter battery is a way to produce it on demand, without interrupting the site’s activity.

Demand response aggregator

The contractual role that declares consumption modulations and monetises them on the market mechanisms. A site can take on that role itself or entrust it to a third party, depending on the thresholds it reaches and the obligations it accepts.

E

EMS

Energy management system

The control layer that decides, at every moment, whether the battery charges, discharges or stands idle. It turns an objective – shave a peak, self-consume, answer a market signal – into power setpoints.

EMS and monitoring

Enedis

The distribution system operator (DSO) for most of mainland France, in charge of the low-voltage (BT) and medium-voltage (HTA) networks. Enedis handles a site’s grid connection to the distribution network and the metering behind its network charges.

F

FCR

Frequency containment reserve

The first line of frequency reserve, called réserve primaire in France. It reacts within seconds to frequency deviations on the European grid, to contain the drift before other reserves take over.

The value stack

G

Grid connection

The physical and contractual link between a site and the public grid. Its lead times and constraints often set a project’s schedule more than the delivery of the equipment does.

H

HTA

Haute tension A

Medium voltage, 1–50 kV – one of the three voltage levels of the French grid, between BT (low voltage) and HTB (high voltage, above 50 kV). The voltage level shapes a site’s grid connection and its network charges: an industrial or commercial site connected at HTA pays the HTA-BT part of TURPE.

I

ICPE

Installation classée pour la protection de l’environnement

The French regime for installations classified for environmental protection – those that present risks or nuisances. A battery energy storage system falls under heading 2925-2, in the declaration regime above 600 kW of cumulative charging power on the site.

Does a BESS fall under ICPE

L

LFP

Lithium iron phosphate

A lithium battery chemistry with no cobalt or nickel, widespread in stationary storage for its thermal stability and its long cycle life. In return it stores less energy per unit of mass, which matters little when the installation does not move.

Load curve

The power a site draws, recorded interval by interval over a period. It shows where the peaks are, how long they last and how often they come back – and it is where sizing starts.

N

NEBCO

Notification d’échanges de blocs de consommation

RTE’s demand response mechanism, in force since 1 September 2025: a demand response aggregator declares a consumption modulation measured on a consumption site, and monetises it on the market. A behind-the-meter battery takes part by producing that modulation; the rules themselves name only the site and its consumption.

The NEBCO rules entered into force on 1 September 2025 and replace the NEBEF rules, approved in July 2023.

NEBCO: what has changed since 1 September 2025

P

PCS

Power conversion system

The converter that turns the direct current (DC) of the cells into the alternating current (AC) of the grid, and back. It sets the maximum power of the system, where the cells set its energy capacity.

The six subsystems of a BESS

Peak shaving

Limiting the peak power drawn from the grid by covering the excess with the battery. The height of the excess sets the power the battery must supply, and its duration the energy it must store; sizing takes both into account.

Shaving a peak: which line of the bill

R

RTE

Réseau de transport d’électricité

The French transmission system operator (TSO), in charge of the HTB network and of keeping generation and consumption in balance in real time. RTE operates the market mechanisms that matter to a storage project – the balancing mechanism, the frequency reserves, the capacity mechanism and NEBCO – and publishes their rules.

S

S21

The tariff order that sets the feed-in conditions for rooftop solar in France. Its power thresholds decide which support scheme a project qualifies for, and therefore how an associated storage system is put together.

Why is selling to the grid no longer enough

Self-consumption

Consuming on site the electricity produced on site. A battery shifts in time what would otherwise be exported to the grid, which raises the share consumed on site without changing the production.

Subscribed power

The power level a site contracts with the network operator – the maximum written into its grid-access contract. Exceeding it costs money, which is what peak shaving sets out to avoid; lowering it reduces the fixed part of the network charges.

What TURPE sets

T

TURPE

Tarif d’utilisation des réseaux publics d’électricité

The French tariff for the use of the public electricity networks, which appears on the electricity bill as the network charges (tarif d’acheminement). One part is tied to the subscribed power, the other to the energy withdrawn in each time category (plage temporelle). That structure is what makes the value of peak shaving easy to read.

What TURPE sets