Glossary
The stationary-storage vocabulary, explained simply.
BESS, TURPE, peak shaving, aFRR, mFRR, blackstart… Every technical and regulatory concept you will meet during a storage project — clearly defined, with what it means for your site.
18 terms
All the key terms to understand a BESS project.
Click a term to share its direct URL anchor. Definitions are written for decision-makers, not specialists.
- aFRR
- Self-consumption
- BESS
- Blackstart
- BMS
- Consuel
- EN 62619
- EN 62933
- EPEX Spot
- EVCI
- mFRR
- Peak shaving
- ROI
- RTE
- Second life
- SoC
- SoH
- TURPE
aFRR
Automatic Frequency Restoration Reserve — fast frequency balancing on the RTE grid.
- aFRR (automatic Frequency Restoration Reserve) corrects frequency deviations within a few minutes (≈ 5 min). BESS that participate are remunerated by RTE for making their capacity available — a source of passive revenue.
Self-consumption
Direct use, on-site, of the electricity produced locally.
- Self-consumption is the share of solar production actually consumed on site. Without storage, the average rate is 40 %. With a BESS, it climbs to 90 % by storing surplus for evening, night or weekend release.
BESS
Battery Energy Storage System — battery-based energy storage system.
- A BESS captures electricity from the grid or solar panels and releases it at the most valuable moment. For a business, it maximises self-consumption, reduces subscribed power (peak shaving), and unlocks revenue on energy markets.
Blackstart
Restart of a site fully islanded from the electrical grid.
- Blackstart is a BESS's ability to restart a site with no grid voltage, supplying critical loads during recovery. Combined with the backup function (< 20 ms switchover), it secures business continuity.
BMS
Battery Management System — electronic supervisor of the cells.
- The BMS continuously monitors voltage, current and temperature of every cell to keep it inside a Safe Operating Area (SOA). It is the critical component that secures safety, longevity and performance of the BESS.
Consuel
French body that certifies the electrical compliance of an installation.
- A Consuel certificate is mandatory to connect a new installation to the grid. Battwoo delivers BESS turnkey, with Consuel compliance included in the commissioning scope.
EN 62619
European safety standard for stationary lithium batteries.
- EN 62619 specifies safety requirements (short-circuit, overcharge, thermal abuse) for stationary lithium-ion batteries in industrial use. All Battwoo BESS are certified compliant.
EN 62933
European standard for electrical energy storage (EES) systems.
- EN 62933 covers performance, system safety, and environmental conditions of complete storage systems. Battwoo designs its units in compliance with this normative framework.
EPEX Spot
Continental European spot electricity market (day-ahead, intraday).
- EPEX Spot sets short-term hourly electricity prices. Day-ahead clears the day before delivery, intraday within hours of delivery. A BESS can arbitrage those prices: charge low, discharge high — observed spreads up to €600/MWh.
EVCI
Electric Vehicle Charging Infrastructure.
- EV charging infrastructure (EVCI) generates large, unpredictable power peaks. Pairing a BESS with EVCI smooths those peaks, lowers subscribed power, and avoids overshoot penalties.
mFRR
Manual Frequency Restoration Reserve — slower grid flexibility mechanism.
- mFRR (manual Frequency Restoration Reserve) takes over from aFRR within roughly 15 minutes. Manually activated by RTE depending on market conditions. Remunerated separately from aFRR.
Peak shaving
Smoothing of power draw peaks using the battery.
- Peak shaving uses the battery to absorb draw peaks above a defined cap, reducing subscribed power and the TURPE. Especially relevant on sites with EV charging infrastructure (EVCI) or intermittent industrial processes.
ROI
Return on Investment — payback period.
- For a Battwoo BESS, typical ROI sits between 4 and 7 years depending on the site profile and the mix of activated levers (self-consumption, peak shaving, HP/HC, arbitrage, grid services).
RTE
Réseau de Transport d'Électricité — operator of France's high-voltage network.
- RTE operates and balances the French electricity transmission network (400 kV / 225 kV). It remunerates flexible producers and storage assets that contribute to stability — through aFRR and mFRR reserves in particular.
Second life
Reuse of an EV battery for stationary use after diagnostic.
- When an EV battery no longer meets automotive requirements (range), it still holds 70-80 % of its capacity — ideal for stationary use. This second life avoids manufacturing a new battery and divides the carbon footprint by four, with no compromise on the 5,000-cycle warranty.
SoC
State of Charge — instantaneous level of charge of a battery (in %).
- SoC is the energy available at a given moment, expressed as a percentage of the capacity. The BESS controller continuously arbitrates between charge and discharge to keep SoC within the useful window.
SoH
State of Health — residual health of a battery (in %).
- SoH measures the residual capacity of a cell relative to its original nominal capacity. An EV battery typically reaches the stationary-use threshold at 70-80 % SoH — plenty for a 15- to 30-year second life depending on usage profile.
TURPE
French regulated tariff for the use of public electricity networks.
- The TURPE pays for the use of the Enedis and RTE networks. It partly depends on subscribed power. Peak shaving lowers the subscribed power — and therefore the TURPE — a direct lever to reduce a site's bill.
See also: BESS
See also: SoH, BMS, Peak shaving
See also: BESS
See also: BESS
See also: Peak shaving
See also: BMS
See also: Peak shaving
Interested?
Personalised technical and economic study in under 7 days.
Custom battery sizing to maximise gains based on your consumption profile. Free and no-obligation.
Reply within 48 business hours — Confidential