What is the difference between LCOS and the purchase price?

The purchase price (GIK) is the one-time investment amount – for LFP it is approximately €250/kWh. The LCOS (Levelized Cost of Storage, €/MWh) additionally takes into account lifetime, degradation, efficiency, and OPEX over the entire service life. Only the LCOS makes different technologies comparable. LFP: €110/MWh (KPMG AG, Feb. 2026).

Why are FTM revenues not guaranteed?

Balancing energy prices are market-dependent – they arise from the balance between supply and demand in the electricity grid. CUBE CONCEPTS calculates in three scenarios (Base / Conservative / Optimistic), all of which are transparent before you make your decision. The multi-use approach diversifies across FCR, aFRR, mFRR, and spot arbitrage – no single channel risk.

What is the typical ROI and what drives it?

When purchasing, CUBE CONCEPTS expects a static payback period of 2–4 years. For comparison: In the KPMG comparison calculation (10 MW / 40 MWh, pure arbitrage, Feb. 2026), LFP achieves an IRR of 10.5 %. The key drivers are: grid connection capacity, storage duration, marketing, and the available BTM/FTM split. CUBE BatterySizer calculates site-specifically based on your load profile.

What do the three scenarios in the open-book calculation mean?

Base: historical average revenue over the last 12 months. Conservative: a 20% reduction on base revenue. Optimistic: a 15% increase with rising demand for flexibility. All three scenarios will be fully disclosed before signing the contract.

Can I still use §118 – what do I have to do when?

Section 118, paragraph 6 of the EnWG exempts storage facilities that become operational by August 4, 2029 from grid fees on electricity drawn from the grid for a period of 20 years, provided that the electricity is fed back into the grid. According to the AgNes draft determination of the Federal Network Agency of August 6, 2026, this only applies to new projects if the final investment decision is made before the determination is announced, planned for January 1, 2027. For existing grid connections, 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 grid.

How does multi-use perform with a rising BESS inventory in the market?

More BESS in the market increases the supply of balancing capacity – individual channel prices may fall. Multi-Use automatically reacts to this: CUBE EfficiencyUnit shifts marketing to the most profitable channels. According to the AgNes draft, a BTM lever independent of the FTM market will be added starting in 2029: consumption above the ordered capacity costs 2 to 3.5 times the energy charge, and the storage system can avoid this.

Battery storage profitability

Battery storage revenues: BTM reduces costs, FTM generates revenue

Most providers sell hardware or electricity. CUBE CONCEPTS builds the system behind it.

200,000–300,000 €

FTM Revenue Potential / MW / Year

CUBE CONCEPTS benchmark

110 €/MWh

LCOS LFP System

KPMG AG, February 2026

2–4 years

Typical ROI Purchase

CUBE CONCEPTS benchmark

§118: Investment decision according to the AgNes draft before January 1, 2027 – only 83 days

Two revenue streams

Two sources of income – most people see only one

BTM – Cost reduction

✓Peak shaving – reducing the demand charge
✓§19, paragraph 2, sentence 1 – grid fee reduction (until 2028)
✓§118, paragraph 6 – 20 years exemption for electricity fed back
✓Maximize PV self-consumption

FTM – Generating revenue

→FCR – frequency containment reserve
→aFRR – automatic frequency restoration reserve
→mFRR – manual frequency restoration reserve as a supplementary channel
→Spot arbitrage – fully automated

No either/or – Multi-Use combines both revenue sources simultaneously.

Business Case

Five factors determine your business case

This is relevant for you if you have a ≥ 500 kW grid connection (BTM) or can offer balancing energy from 1 MW (smaller systems in a pool) – and want to understand the full revenue mix before making a decision.

Grid connection

BTM: from 500 kW. Balancing energy: minimum offer of 1 MW, smaller systems included in the pool. Multiple locations can be bundled together.

C-rate

2h systems (0.5C) achieved around €259,000/MW in 2025, 1h systems around €151,000/MW (ISEA). For FCR, the TSOs require a minimum activation time of 15 minutes and a 25 % power reserve, not a specific C-rate. Incorrect design = revenue potential left untapped.

Grid operator

Grid fees, peak load time windows and connection conditions differ by grid operator; balancing energy prices apply uniformly nationwide. CUBE analyzes your grid connection specifically for your grid operator.

Regulations

§118: 20 years exemption, according to the AgNes draft only if the investment decision is made before January 1, 2027, commissioning by August 4, 2029. §19 expires at the end of 2028. Those who plan too late will permanently pay more.

BTM/FTM-Split

The revenue mix is determined by how much capacity remains available for FTM marketing after BTM coverage (peak shaving, §19).

Case study

1 MW industrial storage in multi-use operation – in concrete terms

Basis: 1,000 kW / 2,000 kWh LFP system. Calculation example CUBE CONCEPTS with 220,000 € gross revenue, in the lower range of 200,000–300,000 €.

Position	Amount / Year
FTM Gross Revenue / Year (FCR + aFRR + mFRR + Spot Arbitrage)	220.000 €
OPEX / Year (Operations, Marketing, IT)	− 55,000 €
Net Market Revenue / Year	165.000 €
Contracting – 0 € CAPEX, off-balance-sheet
Profit share owner 25 % (on net market revenue after OPEX)	~ 41,250 € / year
Profit Share CUBE CONCEPTS 75 % (Open-Book)	~ 123,750 € / year
Purchase – total investment cost (GIK) ~ 250 €/kWh, 100 % own revenues
All net market revenue to the owner	€165,000 / year

Purchase – Return Metrics

ROI

2–4 years

Reference IRR (KPMG, LFP 10 MW)

10,5 %

Total investment cost (GIK)

~ 250 €/kWh

Contracting – Starting point

CAPEX owner

0 €

Revenue share: 25% profit share on net market revenue after OPEX · Off-balance-sheet treatment possible

Source: Computational example by CUBE CONCEPTS; Reference IRR from KPMG comparison calculation (10 MW / 40 MWh, Feb. 2026) · All information provided without guarantee · Site-specific calculation based on your load profile.

Technology Comparison

What battery technology – and why LFP?

LCOS (Levelized Cost of Storage) is the right measure – not the purchase price. It takes into account investment costs, lifetime, degradation, and efficiency.

Parameter	LFP ✓	ZnBr	NIB *
LCOS (€/MWh)	110	104	127
Degradation / Year	2,1 %	0,3 %	3,0 %
Service life	14 years	25 years	10 years
AC-AC efficiency	87 %	81 %	85 %

LFP: highest IRR of the KPMG comparison calculation (10.5 %) and fast payback; ZnBr has the lowest LCOS.

* NIB = Sodium-ion battery (Na-ion). Basis: 10 MW / 40 MWh / WACC 6 % / 2 full cycles/day. Source: KPMG AG, February 2026, pp. 15–21.

Regulatory windows

What comes when – and what does that mean for your decision?

01.10.2026

MiSpeL: PV + FTM compatible

BNetzA determination: PV system can simultaneously generate FTM revenues without losing EEG subsidies; until 30.09.2027, in agreement with the grid operator and metering point operator.

31.12.2026

§118: Cut-off date for investment decision (draft)

According to the AgNes draft determination, new storage systems will receive the 20-year exemption only if the final investment decision is made before the determination is announced, planned for January 1, 2027.

31.12.2028

Section 19, paragraph 2, sentence 1 of StromNEV expires

Atypical grid usage – last application deadline is September 30, 2028.

01.01.2029

AgNes: new grid fee system

According to the draft of August 6, 2026: capacity price based on the ordered capacity, consumption above it at 2 to 3.5 times the energy charge; no successor to atypical grid usage (BNetzA, GBK-25-01-1#3).

August 4, 2029

§118: last commissioning date

20 years of exemption from grid fees on electricity drawn from the grid, insofar as it is fed back. Time-limited by law; cannot be obtained retroactively. Existing connection: 6–12 months planning lead time.

Unused gross market revenue: calculated at around €17,000–25,000 per month at 1 MW (CUBE CONCEPTS benchmark) · Source: §118 para. 6 EnWG

Contracting vs. Purchase

Contracting or purchase – which is more economical?

Both models have access to the same revenue streams. The difference lies in capital investment and revenue sharing.

Contracting

✓ 0 € CAPEX – no own investment
✓ Off-balance sheet possible (accounting to be checked for each contract structure)
✓ 25 % Profit Share of Net Market Revenues after OPEX
✓ CUBE CONCEPTS handles operation and marketing in full
✓ Purchase option set out in the contract

Example 1 MW

~ 41,250 € / year

Purchase

→ Full own investment (total investment cost ~ €250/kWh)
→ On-balance-sheet – capitalization and depreciation
→ 100 % of net market revenue to the owner
→ Reference IRR 10.5 % (KPMG comparison calculation LFP, 10 MW)
→ Optional: CUBE CONCEPTS Takes Over Operations

Example 1 MW

€165,000 / year

“Our open-book calculation is not a bargaining position – it is the foundation on which partnership works.”

3 scenarios: Base / Conservative / Optimistic – all open before your decision is made.

Manufacturer-independent: at least 3 offers · LCOS-rated · no vendor lock-in. Both models.

Initial Orientation

What perspective applies to you?

Four areas of responsibility – each with a different perspective on the same business case.

You are responsible for investment decisions & balance sheet clarity

Reference IRR 10.5 % (KPMG, LFP 10 MW), off-balance-sheet treatment possible (reviewed for each contract structure), CAPEX relief through Contracting – or full control with a purchase. Open book before your decision.

You are responsible for sustainability goals and CSRD reporting

Less electricity drawn from the grid thanks to PV self-consumption reduces Scope 2 emissions. Eligible as a reinvestment in energy storage under the industrial electricity price (CISAF, paragraphs 121–122). Auditable ESRS-E1 data points by default.

You are responsible for operational safety & plant engineering

FTM operation runs fully automatically – no interference with the operating processes. BTM dispatch is coordinated by CUBE EfficiencyUnit, not by you.

You are responsible for energy procurement and electricity purchase costs

Peak shaving lowers the demand charge. Sections 19 and 118 reduce grid fees. FTM generates active revenue. All from one plant.

Common Objections

Common objections – direct answers

“The numbers sound good – but do they apply to our location as well?”

Location-specific – that’s why: Start with the load profile analysis. Our open-book calculation shows your numbers, not benchmarks. CUBE BatterySizer calculates 250+ operating variants based on your load profile.

“We already have offers from other providers.”

Have these offers been calculated based on your load profile – or based on their portfolio? CUBE CONCEPTS shows you the calculation in full before you commit.

“The market for balancing energy could change.”

Diversified multi-use strategy: FCR, aFRR, mFRR, spot arbitrage, peak shaving, §19. No single-channel risk. If one channel goes down, CUBE EfficiencyUnit automatically optimizes for the remaining revenue channels.

References