Control energy is one of the most attractive revenue streams for operators BESS (“Battery Energy Storage System” (or battery storage) in the so-called Front-of-the-Meter (FTM) Operation. While many companies primarily use their storage in behind-the-meter (BTM) operations for self-consumption optimization, peak shaving, or load shifting for purchasing optimization, participating in the grid services market offers additional, predictable revenue.
This post shows, how ancillary services work, what the prerequisites are, and what revenues are realistic.
Is ancillary services with BESS economically worthwhile?
Yes – and quite clearly., if size, operational strategy, and marketing align. A current practical example (as of 2025) shows the economic dimension:
- BESS Size: 10 MW power / 20 MWh capacity
- Deployment: 100 % balancing energy (e.g., PRL, 4-hour auction blocks)
Gross revenue per year:
- Capacity revenues: approx. 438.000 €
- Energy revenue: approx. 175.200 €
- Total: run 613,200 € per year
In reality, however, discounts must be taken into account, including through:
- Availability factors (typically approx. 90 %)
- System Calibrations and Pre-qualifications
- Maintenance and technical downtimes
- Asymmetric calls (positive/negative reserve energy)
This results in a realistic Net annual income of approximately €550,000 to €595,000 for a 10 MW system.
Classification for Practice
- The proceeds are approximately €55,000–€60,000 per MW annually
- reserve energy is therefore a Key economic driver for large BESS
- At the same time, sufficient flexibility remains to integrate additional use cases (e.g., trading, or PV optimization).
Important: Pure grid control operation is possible, but often less economically optimal than Combined Operating Model (Multi-Use).
Why are battery storage systems ideal for grid balancing power?
Battery storage offers crucial advantages:
- Extremely fast reaction times (second range)
- High flexibility (loading and unloading possible)
- Automated control
- Low mechanical stress
This makes them particularly suitable for short-term interventions – especially in the Primary and secondary regulation.
An overview of the three types of balancing energy
1. Primary Control Power (PRL / FCR)
Most important market for BESS:
- Response time: ≤ 30 seconds
- Waiting time: 15 minutes
- Compensation: Performance Bonus
- Deployment: immediate stabilization of grid frequency
2. Secondary Operating Reserve (SRL / aFRR)
- Response Time: ≤ 5 minutes
- Hold time: ≥ 15 minutes
- Remuneration: Service + Work price
- Use: medium-term balance
3. Minute Reserve (MRL / mFRR)
- Response time: up to 7.5 minutes
- Wait time: up to 60 minutes
- Activation: manual
- Deployment: long-term stabilization
Technical Requirements for BESS in the Frequency Regulation Market
For participation – particularly in primary control reserve – clear Minimum requirements:
- Performance Greater than or equal to 1 megawatt
- Available capacity ≥ 0.25 MWh
- Response time Less than 30 seconds
- Standby time 15 minutes
- Operating mode fully automated / remotely controllable
- System Integration Connection to a virtual power plant
- Certification according to regulatory requirements
Important: The battery must positive and negative grid control energy deliver.
In practice this means: Operation in half-charged state (standby mode).
How does the balancing energy market work?
Marketing is carried out through two central markets:
- Regulated labor market – daily tenders
- Balancing power market (RLM) – weekly tenders
Features:
- Participation via Aggregators or direct marketers
- Auctions by Merit Order and Pay-as-Bid Principle
- Distinction between:
- positive / negative control energy
- Performance and work prices
The tenders are organized and published centrally.
How high are the revenues really?
The revenues fluctuate depending on market conditions, but typical values are:
- Physical Review Letters
- approx. 2,200 – 3,800 €/MW/week (historical)
- currently often around €2,000/MW/week calculable
- SRL
- similar magnitude, but more volatile
Result: Depending on the size of the memory five-figure to six-figure annual revenues realistic.
When is a battery storage system (BESS) worthwhile for grid services?
In practice: From around 2.5 MW of power, the use becomes economically attractive.
Participation is particularly worthwhile if the storage is already in operation under FTM for Power trading Arbitrage trading or for Current reserve) is used. However, BTM operation, which reduces electricity costs, can also be combined, such as:
- Self-consumption optimization (PV Combination)
- Peak shavingPeak Shaving)
- Load shift to atypicalityLoad Shifting)
This is how a Multi-Use Case, which significantly increases the overall return.
Advantages of Grid Services with BESS
- Additional, predictable income
- Minimal wear of the BESS
- Contribution to grid stability
- Combination with other business models possible
- Quick access via aggregators
Role of BESS in the Future Energy System
With the further expansion of renewable energies, the need for flexibility in the power system is increasing massively. BESS will therefore:
- relevant for grid stability
- central building block for volatile energy systems
- Key players in electricity trading and the flexibility market
At the same time, it is expected that:
- Larger storage devices dominate
- smaller systems are used more for self-consumption
- Revenue models are increasingly being combined
Conclusion: Ancillary services make BESS even more economically attractive
Participating in the ancillary services market is one of the most effective ways to significantly increase the economic viability of battery storage. This is especially true for FTM operation: Ancillary services turn BESS from a cost optimization solution into an active revenue model. Under the right conditions - especially with sufficient size and intelligent marketing - it is possible to:
- generate stable additional income
- Amortize investments faster
- Combine multiple business models in parallel
This makes it clear: BESS + ancillary services are a central building block of modern energy strategies in the commercial and industrial sectors.