CUBE Profit Duo Solution · Battery storage for industry and commerce
DUO: Two battery storage systems on one grid connection
Your grid connection can earn money.
Is your business using only part of its grid connection? DUO adds two battery storage systems: one lowers your electricity costs, the other earns revenue in the power market with the unused capacity. Purchase or contracting, without a larger grid connection.
At a glance · Example calculation for contracting
€110649
per year for you
€0
own investment, financed by CUBE
€1.18 million
for you over a 12-year term
Example calculation, first year of operation: 2,500 kW grid connection, of which 1,500 kW for operations, two batteries with 1,000 kW and 2,000 kWh each. The full calculation is shown below under Purchase or contracting.
CUBE Profit Duo Solution
What is DUO?
DUO, the CUBE Profit Duo Solution by CUBE CONCEPTS, is a model with two separate battery storage systems on one grid connection. Battery 1 (BTM, behind the meter) lowers your electricity costs. Battery 2 (FTM, front of the meter) uses the unused connection capacity to earn revenue in the power market. DUO is available for purchase or as contracting.
Your grid connection is sized for the maximum power your business may draw. In day-to-day operations, your business usually uses only part of it. The rest goes unused.
DUO splits your grid connection into two fixed zones. Up to an agreed limit, it belongs to your operations. Battery 1 works here, behind the meter: it buys power when prices are low, shaves your load peaks and stores your solar power. This lowers your electricity costs.
The capacity above the limit stays permanently free. Battery 2 works here, in front of the meter: it provides balancing power to the grid and trades electricity. This earns you additional revenue.
Why two batteries?
Battery 1 is what frees up the capacity for Battery 2. It absorbs your load peaks so your operations stay safely below the limit. Only then is the capacity above it available to the power market at all times.
An energy management system measures continuously at the grid connection and controls both batteries. Neither task takes anything away from the other, and your operations always have priority.
One grid connection
You use the connection you already have
Two batteries
Battery 1 for your operations, Battery 2 for the power market
Two revenue streams
Lower electricity costs and additional market revenue
Purchase or contracting
You invest yourself, or CUBE invests for you
Who is DUO for?
DUO fits your site if
✓ you are an industrial or commercial business connected to the medium-voltage grid
✓ your grid connection is not fully used in daily operations
✓ load peaks and grid fees make up a noticeable share of your electricity costs
✓ your site has room for two battery storage systems close to the grid connection
✓ you want the benefits without your own capital, or prefer to invest yourself
✓ you want to prepare for the new grid fees under AgNes before 2029
DUO is a large-scale storage system for industry and commerce. Whether it pays off at your site is shown by the free potential analysis based on your load profile. An overview of battery storage for industry and commerce is available here.
How DUO works
How DUO splits your grid connection.
Example: 2,500 kW grid connection, of which 1,500 kW is the limit for your operations. The remaining 1,000 kW is permanently available to Battery 2.
YOUR GRID CONNECTION
2,500 kW
stays as it is
1,500 kW
for your operations
→
Battery 1 · BTM
behind the meter: buys low, shaves peaks
→
Lowers your electricity costs
€50,649 per year for you
1,000 kW
unused today
→
Battery 2 · FTM
in front of the meter: balancing power and power trading
→
Earns in the power market
€60,000 per year for you
Your operations always have priority. An energy management system and a power meter measure continuously at the grid connection. They keep your site load and Battery 1 together below the agreed limit, 1,500 kW in this example. Battery 2 only uses the capacity above it.
Battery 1 · behind the meter
Battery 1 lowers your electricity costs.
Lever 1
Smarter power purchasing
The battery charges during low-price hours on the spot market and replaces expensive grid power. The price difference is your gain.
Lever 2
Peak shaving
During peak-load windows, the battery discharges and lowers your peak; outside them, it charges up to the limit. This reduces your demand charges.
Lever 3
Use your own solar power
With a PV system, the battery stores solar power that would otherwise be fed into the grid at a low price. Without a PV system, only this lever is omitted.
Battery 2 · front of the meter
Battery 2 earns in the power market.
Battery 2 markets the reserved capacity through specialized trading partners. This revenue comes on top of the savings from Battery 1.
Market 1
Capacity for grid stability: FCR with a capacity price, aFRR and mFRR with capacity and energy prices.
Market 2
Inertia (instantaneous reserve)
Grid stabilization within milliseconds, a market run by the transmission system operators.
Market 3
Power trading
Day-ahead and intraday: price differences over the day, traded by partners such as enspired and Second Foundation.
Basis of calculation: €275,000 market revenue per MW in the first year of operation, within the range of €244,000 to €319,000 per MW. The trading partner is selected per project. Grid feed-in subject to approval by the grid operator.
Purchase or contracting
You decide who invests.
Same system, same revenue. With a Purchase , you receive the full return on your own capital. With Contracting , CUBE invests and operates, and you receive 25% of the net revenue without any capital outlay. How costs and returns break down is explained in battery storage costs and ROI.
| Purchase | Contracting | |
|---|---|---|
| Your investment | €1040000 | €0 |
| For you per year | €442596 | €110649 |
| of which Battery 1 · Battery 2 | €202,596 · €240,000 | €50,649 · €60,000 |
| Payback Battery 1 · Battery 2 | 2.6 · 2.1 years | not applicable |
| For you over 12 years | €3.69 million after investment | €1.18 million |
| Market risk and operation | with you | with CUBE, with purchase option |
Example calculation, first year of operation: 2,500 kW grid connection, of which 1,500 kW for operations, two batteries with 1,000 kW and 2,000 kWh each, 12-year term. Battery 1: €215,596 savings minus €13,000 operating costs. Battery 2: €275,000 market revenue (assumption within the range of €244,000 to €319,000 per MW) minus €35,000 operating costs. Totals over 12 years include degradation. Grid feed-in subject to approval by the grid operator. We calculate your figures from your load profile. No guarantee.
Why now
From 2029, ordered capacity is what counts. Two deadlines expire in 2027.
AgNes from 2029
Under the draft determination of the Federal Network Agency (BNetzA), the demand charge is abolished. You order capacity annually; any draw above it costs 200 to 350% of the energy price.
Section 19 is phasing out
Atypical grid use and baseload discounts end in 2028. Transition until 2031 only for existing arrangements, for atypical use above 10 GWh per year.
Section 118 for Battery 2
Up to 20 years without grid fees on charging power, to the extent it is fed back into the grid. Binding order before January 1, 2027, proof by March 31, 2027, commissioning by August 4, 2029.
Grid connections are scarce
Expansions take years. DUO uses the connection you already have.
Sources: Federal Network Agency (BNetzA), draft determination AgNes (GBK-25-01-1#3) of August 6, 2026 · Section 118 (6) EnWG · Section 19 (2) StromNEV · preliminary, subject to change · As of November 2026
Your implementation
Both batteries turnkey from a single source.
01
Project start
Month 1
Load profile, grid connection and site for both batteries
02
Concept
Months 1–2
Design of both batteries, limit and economics
03
Engineering
Months 2–3
Safety, energy management and metering concept, grid compatibility
04
Planning
Months 2–5
Selection and contracting of the general contractor, permits
05
Construction
Months 5–8
Coordination, construction controlling, certification
06
Commissioning
Months 7–9
Grid connection, control, start of marketing
Schedule indicative, depending on grid operator and permits. Project marketing is included in the service agreement: construction diary, press release, photos and videos, inauguration with press.
References
Chosen as energy partner.
Magna · Valeo · Tenneco · ITW · voestalpine
150+
PV projects delivered across Europe
400+ MWh
storage in implementation in Germany and the Czech Republic
Frequently asked questions about DUO
Your questions, answered up front.
What is DUO?
What is the difference between BTM and FTM?
Who is DUO for?
What does DUO deliver per year?
Who controls the two batteries?
Purchase or contracting: what is the difference?
What changes from 2029 with AgNes?
Do I need my own PV system?
What if market revenue declines?
What about fire protection?
Related topics
As of November 2026 · CUBE CONCEPTS GmbH, Kaarst · Figures: example calculation for the first year of operation, Battery 2 revenue as an assumption within the range of €244,000 to €319,000 per MW · Regulation: Federal Network Agency, draft determination AgNes of August 6, 2026, Section 118 (6) EnWG, Section 19 (2) StromNEV
Your next step
Send your load profile – free potential analysis.
1
Send your load profile
Your load profile, electricity bill and grid connection contract are all we need
2
We calculate DUO
Design of both batteries for your site, purchase and contracting compared
3
Your proposal
With all figures, deadlines and the schedule for your project