Battery Storage Glossary: 58 Technical Terms That Shape Every Decision
From AgNes to §118: Definitions for regulated energy, network charges, economic efficiency and regulation – in industrial and commercial use. With legal bases and source references.
Which BESS terms are most relevant for industrial companies?
This glossary includes 58 terms from the fields of battery storage technology, regulation-based energy, grid fee optimization, and regulation engineering. All definitions are tailored for industrial and commercial applications of 750 kW or more.
BESS decisions are made in industrial companies by decision-makers who often lack training in energy technology – CFOs, investment managers, energy buyers, plant managers. At the same time, the relevant terms are often overloaded with technical terms or used inconsistently: FCR and aFRR are confused, §19 S.1 and S.2 are treated as one regulation, and net tariff effect of MiSpeL is incorrectly assessed. This glossary focuses on precision – for people making investment decisions, not for energy specialists.
All definitions follow a uniform format: Term, definition in one sentence, explanation, and source citation. Terms that are regulatorily critical (§19 S.1 vs. S.2, BK4-22-089, AgNes) include an explicit reference to common confusions or misunderstandings.
Why is precise terminology crucial in BESS projects?
Mistakes in terminology lead to incorrect decisions. A company that confuses §19 S.1 and S.2 is planning on the wrong basis for the application. A company that misinterprets the net cost effect of MiSpeL is calculating incorrect savings. A company that uses BK4-22-089 as an argument against §19 S.2 is opting out of a still valid instrument until December 31, 2028.
The market for BESS consulting is confusing. Many providers use vague terms to make products appear more attractive. This glossary is based on legal texts, BNetzA procedures, publications by transmission network operators and independent studies, not on manufacturer representations. Terms for CUBE CONCEPTS services are marked with „Source: CUBE CONCEPTS“. Those who make decisions based on precise terms will make better decisions.
§
Exemption from network charges for electricity supply for 20 years, for storage systems with commissioning until August 4, 2029, provided that the electricity is again fed into the grid. Since December 2025, partial back-feed is sufficient; this also makes exemption possible for storage systems behind an industrial connection. According to the AgNes draft regulation of August 6, 2026, it applies to new projects only if the final investment decision is made before the publication of the determination, planned for January 1, 2027. The strongest long-term individual lever in the economic calculation.
Source: §118 para. 6 EnWG · BNetzA, AgNes draft determination of 06.08.2026
Grid-oriented control of controllable consumer devices over 4.2 kW, including power storage during peak demand; against reduced grid fees; since April 1, 2025 also with time-variable grid fees (Module 3). Applies only to connections in network levels 6 and 7 (low voltage). Industrial storage on the medium-voltage network is not included.
Source: §14a EnWG · BNetzA determination BK6-22-300
Individual grid fee for atypical network usage: The customer’s peak load in the network operator’s peak load periods must be within the significance threshold (e.g., 20 % in the medium voltage range) and at least 100 kW below its annual peak load. The fee is at least 20 % of the published grid fee. Notification to the BNetzA by September 30, proof by June 30 of the following year. Valid until December 31, 2028; the AgNes draft does not provide for a successor scheme.
Source: §19 Paragraph 2 Sentence 1 of the StromNEV · BNetzA determination BK4-13-739 · BNetzA, AgNes draft determination of 06.08.2026
A
Automatic frequency recovery reserve (secondary control output). Full activation within 5 minutes. The output is procured daily the day before at a pay-as-bid price, with the control work being accessed via the European platform PICASSO since 2022. The most significant revenue channel for battery storage in 2025: the aFRR output of a 2-hour storage unit increased by 39 % to over €146,000/MW.
Source: regelleistung.net · ISEA Battery Revenue Index (RAUTH Aachen), via pv magazine 23.01.2026
General grid tariff system for electricity: Regulatory procedure of the Federal Network Agency (GBK-25-01-1#3) for grid tariffs from January 1, 2029, when the StromNEV expires. According to the draft of August 6, 2026, industrial customers pay a capacity fee for an annually ordered capacity; obtaining this capacity costs 2 to 3.5 times the labor cost. No follow-up is provided for atypical grid usage; existing users with over 10 GWh retain a frozen average discount until the end of 2031; the bandwidth cap applies only to existing agreements. New grid-connected storage systems charge a capacity fee (BNetzA estimate 4 to 7 €/kW per year); they do not pay a labor fee. Final determination planned for the end of 2026.
Period until the investment is repaid from the ongoing net proceeds. CUBE CONCEPTS’ benchmark for the BESS purchase in the multi-use operation (1 MW / 2 MWh, approximately €500,000 investment, €145,000–245,000 net market revenue per year): 2–4 years, calculated statically. For comparison: In the KPMG comparison calculation (10 MW / 40 MWh, pure arbitrage), the discounted payment flows for LFP are positive after nine to ten years. This applies only to the purchase model, not to the one Contracting without own investment.
Source: CUBE CONCEPTS · KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 21
Net tariff reduction under §19, paragraph 2, sentence 1 of StromNEV for customers whose maximum load in the high-load time windows (HLZF) of the network operator is significantly below their annual maximum load (significant threshold, at least 100 kW). Discount up to 80 %. Valid until 31.12.2028; according to the AgNes draft without successor scheme, around 6,000 companies are currently using it.
B
Battery Energy Storage System. Stationary system for electrochemical energy storage. In an industrial context, from 750 kW / 1,500 kWh. CUBE CONCEPTS entry-level size.
Source: IEC 62933 standard series
Balancing deviations between forecasted and actual energy consumption within one's own balancing group. Battery storage buffers forecast deviations and avoids balancing energy costs.
Source: Bilanzkreissystem according to § 4 StromNZV (until 31.12.2025); since then, regulations of the BNetzA
Determination by the Federal Network Agency on February 15, 2023 for band load customers under §19, paragraph 2, StromNEV in the energy crisis: Certain network and market-related load responses, such as load shedding at the request of the transmission network operator or under-consumption during high-price hours, were not taken into account for usage hours and minimum consumption. Extended until December 31, 2025; expired since then. The band load privilege itself remains in effect until December 31, 2028; atypical network usage (clause 1) was not affected.
Operational dimension of the battery storage system within the company’s internal grid, behind the network connection meter. BTM applications: peak shaving, §19 atypical network usage (until 2028), self-consumption optimization, and from 2029 according to the AgNes draft, the avoidance of consumption exceeding the ordered capacity.
Source: §19 Paragraph 2 Sentence 1 of the StromNEV · BNetzA, AgNes draft determination of 06.08.2026
C
Capital Expenditure. One-time investment costs: BESS hardware, grid connection, planning, installation, commissioning, CUBE EfficiencyUnit, prequalification. Under the CPFS model: CUBE CONCEPTS bears all CAPEX costs until ownership is transferred.
Source: CUBE CONCEPTS Project Experience
Contract form without own investment: CUBE CONCEPTS invests, operates and markets the storage facility; the site owner receives 25% % of the net market revenue after OPEX. One of the two contract forms of CPFS, in addition to the purchase. Differentiation from the purchase: no CAPEX risk, usually no balance sheet asset (verification per contract), shorter decision-making processes. Open-book terms before contract conclusion. → Page: BESS Contracting
Source: CUBE CONCEPTS GmbH · Contracting Framework Agreement
CUBE Profit Flex Solution: CUBE CONCEPTS’ three-phase operating model for free network connection capacity. Phase I Market Revenue (FTM), Phase II On-Site Utilization (BTM), Phase III Both combined. Available as Contracting (0 € CAPEX, 25 % of Net Market Revenue) or Purchase (100 % of Revenue). Open-Book before contract conclusion. → Page: CPFS
Source: CUBE CONCEPTS GmbH
The charging or discharging rate of a battery storage system relative to the nominal capacity. 1C = complete charge or discharge in 1 hour, 0.5C in 2 hours. Transmission grid operators do not specify a specific C rate; for battery storage systems, the minimum activation time is 15 minutes and the maximum power is at least 1.25 times the marketed power. Economically speaking, the storage duration counts: 2-hour systems achieved around €202,500/MW across the market in 2025, while 1-hour systems achieved around €151,000/MW (ISEA Battery Revenue Index).
Source: ÜNB, PQ conditions (regelleistung.net) · ISEA Battery Revenue Index (RAUTH Aachen), via pv magazine 23.01.2026
Corporate Sustainability Reporting Directive: EU directive on sustainability reporting under the ESRS. According to the Omnibus Directive (EU) 2026/470, companies with more than 1,000 employees and more than €450 million in revenue are required to report; the second wave applies for the 2027 financial year for the first time; the German implementation is yet to be determined. A battery storage system can reduce grid connection and thus Scope 2 emissions through higher PV self-consumption (ESRS E1). CUBE CONCEPTS’ monthly open-book reporting provides the data for this.
Source: Directive (EU) 2022/2464 · Directive (EU) 2026/470 · ESRS E1
CUBE CONCEPTS Analysis Tool. Calculates 250+ operating variants based on load profile data and determines optimal storage technology, capacity, and performance.
Source: CUBE CONCEPTS GmbH
CUBE CONCEPTS control and marketing infrastructure for battery storage. Coordinates FTM marketing (FCR, aFRR, mFRR, Arbitrage) and BTM applications (Peak Shaving, §19, Self-consumption) in real time. Multi-Use operation.
Source: CUBE CONCEPTS GmbH
D
Capacity loss of a battery storage system over its operating life. KPMG comparison calculation for two full cycles per day: LFP 2.1 %, ZnBr 0.3 %, NIB 3.0 % per year. The end of life is typically reached at around 70% % of the original capacity.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 15
Company that markets storage and other equipment in the electricity and regulation energy markets. For regulation energy, the provider must be pre-qualified with the transmission network operators; according to the UBN’s provider list (as of 08.07.2026), there are 44 companies. Since the minimum bid size is 1 MW, aggregators group smaller installations into pools.
Source: regelleistung.net
E
BTM strategy: Self-generated PV electricity is stored in the battery storage system and used later on – instead of being fed into the grid. This reduces the electricity bill (operating cost) and increases the PV self-consumption rate. MiSpeL (since 01.10.2026) enables simultaneous self-consumption and FTM marketing without losing the EEG subsidy.
Control system that coordinates the battery storage’s charge and discharge cycles in real time. Optimizes the BTM/FTM split daily: Peak-Shaving Dispatch, §19-Atypical Detection, FTM bidding (FCR, aFRR, mFRR, Arbitrage), and self-consumption simultaneously. CUBE EfficiencyUnit is CUBE’s own EMS – the control infrastructure for multi-use operation.
Source: CUBE CONCEPTS GmbH
F
Frequency Containment Reserve (Primary control function). Full power within 30 seconds at ±200 mHz frequency deviation in the European interconnected network. Daily auction the day before in six 4-hour products, remuneration based on unit price (pay-as-cleared). For battery storage systems, a minimum activation time of 15 minutes applies. Revenue in 2025 around €106,000/MW (−6.9 %, ISEA).
Source: regelleistung.net · ISEA Battery Revenue Index (RAUTH Aachen), via pv magazine 23.01.2026
Operational dimension of battery storage in the wholesale market. FTM revenues: FCR, aFRR, mFRR, spot market arbitrage. Runs independently of company operations.
Source: ISEA Battery Revenue Index (RAUTH Aachen), via pv magazine 23.01.2026
G
All the investment costs of a BESS installation: hardware (battery modules, inverters, containers), grid connection, planning, permitting, installation, commissioning, EMS, prequalification. Guideline: around €250/kWh for LFP, including the approach of the KPMG comparison calculation (10 MW / 40 MWh; ZnBr €360/kWh, NIB €275/kWh). GIK is the basis of the LCOS and amortization calculation when purchasing. CUBE CONCEPTS Contracting bears the GIK in full.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 18 · CUBE CONCEPTS
H
Daytime windows, determined by the network operator for each network or coverage level and for each season from its previous year’s load, and published by October 31 for the following year. They apply only on weekdays. For atypical network usage under §19, paragraph 2, sentence 1, StromNEV, the customer’s maximum load in these windows must be significantly below its annual maximum load; therefore, battery storage is intentionally discharged into the HLZF.
Source: §19 Paragraph 2 Sentence 1 of the StromNEV · BNetzA determination BK4-13-739
I
Formal date of the first grid-parallel operation of an installation. Relevant for §118, paragraph 6 of the EnWG: Commissioning by August 4, 2029 is a prerequisite for the 20-year exemption; according to the AgNes draft, the investment decision must also be made before January 1, 2027.
Source: §118 para. 6 EnWG · BNetzA, AgNes draft determination of 06.08.2026
Stationary battery storage for industrial and commercial use. CUBE CONCEPTS entry-level size: from 750 kW / 1,500 kWh. Typical project sizes in the CUBE portfolio: 1–10 MW.
Source: CUBE CONCEPTS Project Experience
Electricity price relief for the billing periods 2026 to 2028 for sectors with a significant risk of displacement (partial list 1 of Annex I of the KUEBLL, according to BMWE 91 sectors and sub-sectors). Half of consumption is subsidized at a basic reference price of 50 %, with the target price of 5 ct/kWh not to be exceeded; for 2026 this is 3.744 ct/kWh. At least 50 % of the granted amount must be invested within 48 months in measures that reduce the electricity system costs; energy storage is explicitly mentioned; a third party may implement and finance the measure. 10 % Bonus if 80 % of the commitment flows into flexibility. → Page: Industrial electricity price
Source: Industrial electricity price directive of 27.04.2026 (BAnz AT 06.05.2026 B1) · BAFA · CISAF points 121–123
Internal interest rate: the discounting rate at which the net present value of the investment becomes zero, i.e. the average annual return. KPMG comparison calculation (10 MW / 40 MWh, two full cycles per day, arbitrage, WACC 6 %, project-specific): LFP 10.5 %, ZnBr 9.5 %, NIB 7.2 %. Site-specific values in multi-use operation differ from this and result from the open-book calculation.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 21
K
The option in Contracting the agreement granted by the site owner to acquire the BESS facility after market operation by CUBE CONCEPTS under previously agreed conditions. Ensures full control over the facility at a defined time without initial capital risk. In the case of the industrial electricity price, the investment in the storage facility counts; it can also be implemented and financed by a third party, according to the BAFA.
Source: CUBE CONCEPTS GmbH · BAFA leaflet on decarbonization measures, Chapter 3.5
L
15-minute interval measurement data of the electrical consumption of a plant from the RLM meter. Basis for every BESS dimensioning and profitability analysis: identify load peaks (peak shaving potential), check §19 qualification (high-load behavior), calculate FTM revenue potential, optimize storage capacity. A load profile of 12 months is sufficient for a complete analysis.
Source: Section 55 MsbG CUBE CONCEPTS GmbH
Levelized Cost of Storage: discounted total costs per MWh stored over the lifetime, including investment, operation and degradation. Central benchmark indicator for storage technologies. KPMG comparison calculation (10 MW / 40 MWh, WACC 6 %, two full cycles per day): ZnBr €104/MWh, LFP €110/MWh, NIB €127/MWh.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 20
Component of the network fee according to §17 StromNEV. The annual performance fee results from the performance price multiplied by the annual maximum performance, i.e., the highest quarter-hour value in the billing year. A single peak thus determines the performance costs for the entire year. From 2,500 usage hours, a higher performance price and a lower labor price apply. Peak shaving with BESS cuts this peak and lowers the performance fee, regardless of §19.
Source: §17 Electricity Ordinance
Lithium iron phosphate: Standard technology for stationary industrial storage. In the KPMG comparison calculation, the highest IRR (10.5 %) for LCOS is €110/MWh, just above ZnBr (104 €/MWh). Up to 10,000 cycles or 14 years with two full cycles per day, degradation 2.1 % per year, AC-AC efficiency 87 %, maximum discharge depth around 90 %. Thermally stable, cobalt-free.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026
M
Manual Frequency Restoration Reserve (Minute Reserve). Complete activation within 12.5 minutes. The power is procured daily the day before in 4-hour products, with the regulation work since 2022 accessed via the European platform MARI. For battery storage, an additional channel is available in addition to FCR and aFRR.
Source: regelleistung.net
Market integration of storage facilities and charging points. BNetzA decision of 01.10.2026 regarding EEG support and tariff privileges for mixed storage use. Allows simultaneous BTM and FTM operation without loss of EEG support, until 30.09.2027, in agreement with network and metering station operators. No § 19 privilege, but it has an effect on the net tariff exemption for electricity volumes that are fed back into the grid via § 118, paragraph 6, point 3 of the EnWG.
Source: BNetzA, MiSpeL determination of 01.10.2026 · Article: MiSpeL definition explained
Simultaneous operation of FTM marketing and BTM applications using the same battery storage system. CUBE EfficiencyUnit coordinates both aspects in real time. No capacity goes unused.
Source: CUBE CONCEPTS GmbH
N
The connection point between the operating site and the public electricity grid. The free network connection capacity determines the maximum installable BESS output. For regulated energy, a minimum bid size of 1 MW applies; smaller systems are marketed in the pool. An existing connection is an advantage: In 2025, only 8 % of the connection requests for battery storage were granted in the distribution network. The connection capacity is the most important site-specific planning parameter.
Source: § 17 EnWG · regelleistung.net · BNetzA/SMARD, 20.08.2026
The fee for using the electricity grid consists of labor costs and power costs (annual maximum power); surcharges and taxes are added separately. For an industrial customer with a 24 GWh annual consumption, the net grid fee on April 1, 2025 averaged 4.28 ct/kWh, from a total price of 19.09 ct/kWh, around 22 % without any discounts. The average transmission grid fee will initially rise to 3.54 ct/kWh in 2027 (2026: 2.86 ct/kWh).
Source: BNetzA monitoring report 2025 · ÜNB, press release 1 October 2026 · §17 Electricity Ordinance
Alternative lithium-ion technology: higher energy density than LFP, but higher thermal risk and cobalt dependency in the supply chain. According to KPMG, LFP has made significant progress in degradation behavior compared to NMC. It has largely replaced LFP in the stationary storage market. CUBE CONCEPTS recommends LFP for multi-use BESS in industrial applications due to cycle stability and thermal stability.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026
O
Accretion, in which the asset neither appears as an asset nor as a lease liability in the balance sheet of the entity owning the asset, without affecting the equity ratio or credit lines. Relevant for companies with bank financing or IFRS reporting obligations. Contracting Possible if the contract under IFRS 16 does not establish a leasing relationship; the review is performed per contract with the auditor.
Source: IFRS 16
Governance principle in the CPFS model: All revenue and cost items are fully visible before the contract is signed – no information asymmetry between CUBE CONCEPTS and the site owner. Basis for auditable, IFRS-compliant accounting structure. Not: public price publication.
Source: CUBE CONCEPTS GmbH
Operating Expenditure. Running operating costs: Maintenance, monitoring, market connection, insurance, reporting. In the CPFS model: CUBE CONCEPTS bears all OPEX until ownership transfer.
Source: CUBE CONCEPTS Project Experience
P
Peak load capping in the industrial grid connection. Reduces the annual power component of the grid fee (§17 StromNEV), which is calculated at the highest annual load point.
Source: §17 Electricity Ordinance
The aggregation of several systems into a pool that jointly participates in regulation energy markets is coordinated by a prequalified provider. Since the minimum bid size is 1 MW, pooling enables the generation of regulatory energy revenues even for smaller systems; a pool is limited to one regulatory zone. CUBE CONCEPTS implements storage projects starting at 750 kW.
Source: regelleistung.net CUBE CONCEPTS GmbH
Formal approval by the connection transmission network operator for regulated energy, regulated in the PQ conditions of the ÜNB in accordance with the EU guideline SO GL. Requirements include, among others, the activation times (FCR 30 seconds, aFRR 5 minutes, mFRR 12.5 minutes) for battery storage systems; in the FCR, a minimum activation time of 15 minutes and a power reserve of 25 %%. The minimum bid size is 1 MW.
Source: 50Hertz, Amprion, TenneT, TransnetBW, PQ conditions (regelleistung.net)
Compensation in Contracting: As the site owner, you receive 25 % of the net market revenues after deducting all OPEX (operations, marketing, IT), without any own investment or operational costs. CUBE CONCEPTS receives 75 % and bears all investment and operational costs.
Source: CUBE CONCEPTS GmbH · Related terms: Open-Book, CPFS, OPEX
R
General term for system services for frequency maintenance in the European interconnected network (target frequency 50 Hz). Includes FCR (full power in 30 seconds), aFRR (5 minutes) and mFRR (12.5 minutes). Battery storage is particularly suitable because of its rapid response. The four German transmission network operators jointly publish regelleistung.net for the whole of Germany. → Page: Control Energy
Source: regelleistung.net 50Hertz, Amprion, TenneT, TransnetBW
Regulatory performance measurement: Measurement method for end-users with an annual consumption of more than 100,000 kWh. Provides 15-minute load data, which forms the basis for BESS sizing, §19-Atypik proof, and operational optimization.
A measure of the profitability of an investment: ROI = (Profit ÷ Investment Costs) × 100 %. For the BESS purchase in the multi-use operation, CUBE CONCEPTS estimates 2–4 years of static amortization, which corresponds to an annual return of around 25–50 % of the investment. With the BESS Contracting, no CAPEX is required; what matters is the profit share.
Source: CUBE CONCEPTS, benchmark for 1 MW / 2 MWh
S
Current battery storage charge level in percent of rated capacity (0 % = empty, 100 % = full). The EMS continuously monitors the SOC: For FCR that can be accessed in both directions, it typically holds around 50 %; for peak shaving, it holds enough energy to handle the expected peak loads. The SOC management determines the availability for all markets.
Source: IEC 62933 standard series · CUBE CONCEPTS GmbH
Trading on the Day-Ahead Market (daily auction, since October 1, 2025 in quarter-hour increments) and the Intraday Market (continuous, within a German regulatory zone up to 5 minutes before delivery). Battery storage charges at low or negative prices and feeds in high prices. Negative wholesale prices were recorded in 2025 in 573 hours (2024: 457). With increasing share of EE, the price spreads are widening.
Source: BNetzA/SMARD, 20.08.2026 · BNetzA, press release 03.01.2025 EPEX SPOT SE
Ü
Operator of the high-voltage grid (220 and 380 kV). In Germany, there are four transmission system operators: 50 Hertz, Amprion, TenneT, TransnetBW, each responsible for a control zone. They jointly write down the control energy (FCR, aFRR, mFRR) in the German network control system and award the prequalification. The tender prices apply to the entire country, not per control zone.
Source: regelleistung.net, German Network Regulatory Association · § 12 EnWG
V
Usage intensity indicator: annual work (kWh) divided by annual maximum output (kW). Relevant for the band load under §19, paragraph 2, sentence 2 of the StromNEV: at least 7,000 usage hours and more than 10 GWh per year at a collection point; discount up to 80, 85 or 90 %. Valid until 31.12.2028, according to the AgNes draft only for existing agreements thereafter. BK4-22-089 was a crisis special rule limited to 31.12.2025 and did not end the band load.
Source: §19 para. 2 StromNEV · BNetzA BK4-22-089A01 · BNetzA, AgNes draft determination of 06.08.2026
A complete charge-discharge cycle (0 % → 100 % → 0 % charge state). Key indicator for lifetime and LCOS. Maximum cycles according to KPMG (manufacturer’s specifications): LFP 10,000, ZnBr 20,000, NIB 7,000. The KPMG comparison calculation assumes two full cycles per day.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 15
W
Weighted average cost of capital – the minimum return requirement on invested equity and debt capital. Basis for the LCOS calculation: KPMG uses a real WACC of 6 % (10 MW / 40 MWh) in the investment case from February 2026. The lower the WACC, the more favorable the calculated LCOS. Companies with a lower cost of capital achieve a calculated LCOS that is lower.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 18
Z
Battery based on zinc-bromide for storage duration of approximately four to twelve hours. In the KPMG comparison calculation, lowest LCOS (104 €/MWh) and highest NPV, but higher investment (360 €/kWh), lower AC-AC efficiency (81 %) and lower IRR (9.5 %) than LFP. Degradation 0.3 % per year, up to 20,000 cycles, discharge depth up to 100 %. Lower energy density, installation according to KPMG also possible in commercial and industrial halls.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, p. 15–21
CUBE CONCEPTS GmbH · /knowledge/glossary/ · Date: 09.10.2026
What are the legal deadlines until 2029?
Five regulatory instruments are relevant for BESS decisions until 2029 – with different deadlines, different mechanisms of action and a critical risk of confusion.
The table below provides an overview. Two points are particularly often the subject of misunderstandings: First, MiSpeL is not an own net charging instrument, but acts through legal references: According to § 118, paragraph 6, item 3, of the EnWG and § 19, paragraph 2, item 16 of StromNEV, its rules for returned amounts of electricity also apply to the exemption from net charging and the surcharge for special network use, according to the BNetzA until the end of 2028. The privileges under § 19, paragraph 2, item 2 and 2 of StromNEV are not regulated by MiSpeL. Second, BK4-22-089 only concerns §19, paragraph 2, item 2 (band load), and expired on December 31, 2025 – §19, paragraph 2, item 1 (atypical network use) is completely independent of this and applies until December 31, 2028. Anyone who does not know this distinction makes erroneous planning decisions.
| Instrument | Effect | First |
|---|---|---|
| §14a EnWG | Time-variable network charges (only network levels 6 and 7) | As of April 1, 2025 |
| §19 Paragraph 2 Sentence 1 of the StromNEV | Atypical grid usage | Until 12/31/2028 |
| MiSpeL | EEG subsidies, levies; network charges under § 118, paragraph 6 | Since 01.10.2026 |
| §118 para. 6 EnWG | 20 J. Exemption from the network fee on the electricity bill, insofar as it is fed back | Investment decision before 1.1.2027 (draft), IBN until 4 Aug. 2029 |
| AgNes | New network tariff system, no atypical follow-up (Draft 06.08.2026) | As of 01/01/2029 |
Common Misunderstanding: MiSpeL and Network Fees
MiSpeL (Market Integration of Storage and Charging Points) is not a net charging reform. The BNetzA’s determination of 01.10.2026 regulates EEG subsidies and tariff privileges when storage mixes grid and EE electricity. However, it still affects net charging fees: Under § 118, paragraph 6, item 3, of the EnWG, its rules apply to electricity volumes that are fed back into the grid and are exempt from net charging fees, while under § 19, paragraph 2, item 16, StromNEV, they apply to the surcharge for special grid usage, according to the BNetzA; both will remain in effect until the end of 2028. MiSpeL does not regulate atypical grid usage and load after § 19, paragraph 2, items 1 and 2, StromNEV. From 2029, the AgNes determination will decide.
§19, paragraph 2, sentence 1 vs. sentence 2: The difference that changes project plans
Section 19, paragraph 2, sentence 2 of StromNEV regulates the band load privilege: at least 7,000 usage hours and more than 10 GWh per year. The BNetzA’s BK4-22-089 decision was a crisis-specific special rule only for band load customers and expired on December 31, 2025; the privilege itself remains in effect until December 31, 2028. Section 19, paragraph 2, sentence 1 regulates atypical network usage (high-load time windows), was not affected by BK4-22-089 and also remains in effect until December 31, 2028. As of 2029, the AgNes draft provides no general continuation for both, only transitional rules for existing cases until the end of 2031. Proper demarcation is a planning prerequisite.
Source: §19 para. 2 StromNEV · BNetzA BK4-22-089A01 · BNetzA, AgNes draft determination of 06.08.2026
What distinguishes LFP, ZnBr and NIB – the three relevant storage technologies in 2026?
By 2026, the BESS market will offer three technically advanced alternatives for stationary industrial storage. The right choice depends on the usage profile, the operational strategy, and the site profile – not on manufacturer preferences.
LFP – Lithium-Iron Phosphate
Standard technology for industrial storage from 750 kW. Advantages: low investment costs (according to KPMG recently significantly reduced), high cycle stability (up to 10,000 cycles), thermal stability, wide availability from Tier-1 manufacturers from Europe, South Korea and China. Disadvantages: lower energy density than NMC, power loss at low temperatures below -10°C. LCOS 110 €/MWh, slightly above ZnBr, but highest IRR of the comparison calculation: 10.5 % (KPMG AG, February 2026Typical storage time is one to four hours. LFP is the first choice for multi-use operation (FCR, aFRR, peak shaving) with daily full cycles.
ZnBr – Zinc bromide (Flow Battery)
Designed for storage durations of approximately four to twelve hours. Advantages: Discharge depth up to 100 %, only 0.3 % degradation per year, up to 20,000 cycles, according to KPMG; no fire risks and therefore also suitable for installation in halls. Disadvantages: Lower energy density and AC-AC efficiency (81 %), more specific system integration, higher investment (360 €/kWh). LCOS at 104 €/MWh, the lowest value in the KPMG comparison calculation. Attractive for self-consumption optimization and arbitrage-heavy operating strategies (KPMG AG, Feb. 2026). Suitable for locations with large daily spreads between favorable nighttime and expensive daytime power.
NIB (Sodium-ion battery / Na-ion) – Sodium-ion
Emerging technology based on inexpensive and abundant raw materials (no lithium, no cobalt). Advantages: Materials with high global availability such as sodium, iron or manganese; discharge depth up to 100 %. Disadvantages: no mass-market storage standard yet 2026; cycle life not yet fully proven in the field; few qualified Tier-1 providers. LCOS €127/MWh, degradation 3.0 % per year (KPMG AG, Feb. 2026; little experience in commercial operation). CUBE CONCEPTS monitors NIB – no standard product currently.
The technology decision is a function of the operating strategy: A storage system for dominant FCR/aFRR marketing with 2–3 full cycles per day requires different requirements than an arbitrage storage system with a daily cycle. CUBE BatterySizer calculates the optimal technology and capacity based on your site-specific load profile – regardless of the manufacturer and without any pre-determined setup. The result is not always LFP. It is always the technology that achieves the lowest life-cycle LCOS in your load profile with the planned operating strategy. For sites with high arbitrage potential and long discharge cycles, ZnBr may be the better choice – this is based on the calculation, not the manufacturer preference.
Source: KPMG AG, Investment Case: Stationary Battery Storage, February 2026, pp. 13–21 · CUBE CONCEPTS Project experience
Which glossary terms are most important according to your role?
Depending on your role in the company, different terms are crucial. This overview will help you get started.
If you are responsible for investment decisions
Priority: CPFS, Open-Book, IFRS 16, Off-Balance, LCOS, §118 para. 6 EnWG (IBN Deadline), CAPEX, OPEX. These terms form the basis for the economic feasibility study and the governance requirements that accompany a BESS investment decision.
§118: Plan the schedule realistically
According to the AgNes draft, the final investment decision must be made before January 1, 2027 falls, the commissioning until August 4, 2029. With an existing power connection, CUBE CONCEPTS expects 6–12 months Until commissioning. New connections are the bottleneck: In 2025, only 8 % of the connection requests for battery storage were granted in the distribution network.
Sources: BNetzA, AgNes draft determination of 06.08.2026 · BNetzA/SMARD, 20.08.2026
If you are responsible for energy procurement and grid fees
Priority: §19, paragraph 2, sentence 1, HLZ, atypical network usage, peak shaving, §118, paragraph 6 of the EnWG, AgNes, §14a of the EnWG, MiSpeL (including a distinction from §19). These terms are directly relevant to action – errors in the use of terminology lead to incorrect planning.
If you are responsible for ancillary services and FTM revenue
Priorities: FCR, aFRR, mFRR, spot arbitrage, prequalification, CUBE EfficiencyUnit, multi-use, full cycles, FTM. An understanding of market mechanisms and remuneration structures is essential for revenue forecasting.
If you are responsible for ESG and CSRD
Priority: BTM, self-consumption, Scope-2 emissions according to the GHG Protocol, CO₂ equivalents, BESS, RLM, CSRD. BESS provides measurable and auditable data points for ESRS-compliant reporting – if the facility is operated in accordance with the documentation. Monthly open-book reporting by CUBE CONCEPTS provides these data by default.
Realized Projects with Tier 1 Industrial Companies
CUBE CONCEPTS has implemented over 150 energy projects across Europe (exclusively in the PV sector). The methodology – open book, vendor-independent, load-based – is the same as that now used for BESS.
What can you find out with your load profile in 30 minutes?
CUBE CONCEPTS analyzes your load profile and calculates specific potential savings: §118 exemption value, FTM revenue, peak shaving savings, §19 atypicality and costs of the ordered capacity from 2029 onwards. Initial assessment in 30 minutes, free of charge, without commitment.
⚠︎ §118: Investment decision according to the AgNes draft before January 1, 2027, Commissioning by August 4, 2029.
Which further BESS pages are recommended?
Frequently Asked Questions about BESS Terms and Regulations
AgNes (General Network Charges Systematicity for Electricity, BNetzA Procedure GBK-25-01-1#3) regulates network charges from January 1, 2029, when the StromNEV and thus §19, paragraph 2 expire. According to the draft of August 6, 2026, industrial customers pay a capacity price for an annually ordered capacity; obtaining it costs 2 to 3.5 times the labor cost. No follow-up is provided for atypical network use. A battery storage system can avoid exceeding the ordered capacity and provide flexibility for a possible new special requirement. The final determination is scheduled for the end of 2026.
According to CUBE CONCEPTS experience, the economic entry point starts at around 750 kW / 1,500 kWh. For regulated energy, a minimum bid size of 1 MW applies; smaller systems are marketed in the pool. CUBE CONCEPTS expects gross market revenues of €200,000–300,000 per MW per year, regardless of a PV system; according to the ISEA Battery Revenue Index, the potential of a 2-hour storage system in 2025 is around €259,000/MW.
CPFS (CUBE Profit Flex Solution) is the three-phase operating model of CUBE CONCEPTS: Phase I Market Revenue (FTM), Phase II On-Site Utilization (BTM), Phase III Both combined. It Contracting is one of the two contract forms: CUBE CONCEPTS invests (0 € CAPEX), you receive 25 % of the net market revenue. When purchasing, you invest yourself and retain 100 % of the proceeds.
FCR (Frequency Containment Reserve) is the primary control performance: full power within 30 seconds. aFRR (Automatic Frequency Recovery Reserve) is the secondary control performance: full power within 5 minutes. In 2025, aFRR was the strongest revenue channel for battery storage; according to the ISEA Battery Revenue Index, aFRR revenue grew by 39 %%.
High-load time windows (HLZF) are daily time windows that the network operator determines for each network level and season based on the previous year’s load; they are published until October 31 for the following year; they apply only on weekdays. For atypical network usage pursuant to §19, paragraph 2, sentence 1 of StromNEV, the customer’s maximum load in these windows must be significantly below their annual maximum load. Battery storage therefore discharges intentionally during the HLZF.
Levelized Cost of Storage: discounted total costs per MWh stored over the lifetime, including investment, operation, and degradation. This allows for storage technologies to be compared. KPMG comparison calculation (February 2026): ZnBr 104 €/MWh, LFP 110 €/MWh, NIB 127 €/MWh. LFP achieves the highest IRR (10.5%) there, despite slightly higher LCOS %.
MiSpeL is the decision of the Federal Network Agency on the market integration of storage and charging points, adopted on 01.10.2026. It enables simultaneous BTM and FTM operation without losing the EEG subsidy. MiSpeL is not a separate network tariff instrument, but according to the understanding of the BNetzA it also applies to electricity volumes that are refunded under § 118, paragraph 6, point 3 of the EnWG. Until 30.09.2027, its use is only possible with the consent of network and metering station operators.
Open-Book means complete transparency of all revenue and cost flows within the CPFS business relationship. Not: public price disclosure. Basis for IFRS-compliant accounting structure and auditability.
The performance fee under §17 StromNEV is based on the highest quarter-hour performance in the billing year: A single unfavorable quarter-hour determines the performance costs for the entire year. The battery storage system automatically cuts this peak. §19 is an additional lever until December 31, 2028, not the basis; as of 2029, according to the AgNes draft, the storage system will also avoid expensive over-subscription of the ordered capacity.
Registered performance measurement: measurement procedures for end-users with an annual consumption of more than 100,000 kWh (§ 55 MsbG). Provides 15-minute load data, which is a prerequisite for BESS sizing, §19-Atypik proof and operational optimization.
Section 19, paragraph 2, sentence 1, StromNEV grants an individual network charge for atypical network usage: The customer’s maximum load in the peak load periods must be within the significance threshold (e.g., 20 % in the medium voltage range) and at least 100 kW below its annual peak load. The charge is at least 20 % of the published charge. Notification by September 30, proof by June 30 of the following year. Applies until December 31, 2028. BK4-22-089 only applied to the band load (paragraph 2).
Section 118, paragraph 6 of the EnWG exempts storage facilities that become operational by August 4, 2029, from network charges for electricity for 20 years, provided that the electricity is again fed into the grid. According to the AgNes regulatory draft of the Federal Network Agency of August 6, 2026, this applies only to new projects if the final investment decision is made before the determination is announced, planned for January 1, 2027. For quantities consumed by the storage facility at the site, the exemption does not apply.
How does CUBE CONCEPTS translate concepts into concrete numbers for your business?
A glossary explains the terms. CUBE CONCEPTS translates these terms into a location-specific open-book calculation – based on your RLM load profile data, the current regulatory requirements, and the current market prices.
The difference between a BESS project that is economical and one that is not lies rarely in the terminology – it lies in the quality of implementation. The CUBE EfficiencyUnit is the control infrastructure, §19 atypicality verification, the demarcation of back-loaded quantities according to §118 and MiSpeL, FCR and aFRR bid submission and peak-shaving dispatch in real time. The open-book calculation is the tool that gives the CFO, audit and energy purchasing the same data base – before the decision is made after signing.
What CUBE CONCEPTS specifically delivers
- Manufacturer-independent tender (min. 3 offers, LCOS-evaluated)
- Open-book calculation based on your load profile data
- LCOS Calculation for LFP and Alternatives
- Three revenue scenarios (Base / Conservative / Optimistic)
- IFRS 16 Compliant Accounting Structure + Off-Balance Sheet Review
- Full prequalification and TSO communication
- Monthly open-book reporting starting from IBN
What other providers often don't deliver
- Transparent calculation before the decision
- Site-specific LCOS calculation
- Manufacturer-independent tender
- Open-Book Billing per Asset
- IFRS 16 Structuring by Auditor Coordination
- Full Atypicality Detection Coordination
Most providers sell either hardware or electricity. CUBE CONCEPTS builds the system behind it – the governance, operational, and revenue structure that industrial companies need to make and justify a BESS decision with conviction.
CUBE CONCEPTS Project Experience · KPMG AG Investment Case, February 2026
Citations
§118 para. 6 EnWGCommissioning by August 4, 2029 · BNetzA, AgNes draft determination GBK-25-01-1#3 of 06.08.2026Investment decision before January 1, 2027; network charges from 2029 · §19 para. 2 StromNEVAtypical network usage and bandwidth load until December 31, 2028 · BNetzA BK4-22-089 / A01Crisis special rule: Band load, expired 31.12.2025 · BNetzA, MiSpeL determination 618-25-02 of 01.10.2026 · §14a EnWGModule 3 since April 1, 2025 · BNetzA monitoring report 2025Grid fee Industrial Engineering 24 GWh · BNetzA/SMARD, 20.08.2026Power connections, negative prices in 2025 · ÜNB, regelleistung.netReserve rule, PQ conditions · KPMG AG: Investment Case Stationary Battery Storage, February 2026 · ISEA Battery Revenue Index, RWTH Aachen, revenues 2025 · Industrial electricity price directive of 27.04.2026, BAnz AT 06.05.2026 B1 · BAFA · EU Commission, CISAF paras. 121–123
CUBE CONCEPTS GmbH · /knowledge/glossary/ · Date: 09.10.2026