Battery energy storage systems (BESS) are considered a key technology for the energy transition, as they offer exceptional flexibility. In the public grid, they are particularly well-suited for Follow-on operation. This refers to the ability of a power plant or storage to continuously adapt its output to fluctuating grid load or schedules – in other words, to ramp up and down flexibly, rather than just running at constant power.
The typical measured variables are:
- Performance gradientThe value is given as „Pb inst/s“ (Power bruto / instantaneous change per second) and describes the current state or the technical load limit.
- „Power Ramp“It is the actual change in power output or decrease in kilowatts or megawatts per unit of time, i.e., the possible schedule in load following operation.
- Minimum operating performanceIt indicates how far a power plant can reduce its output without being shut down.
While conventional power plants are physically sluggish and technically limited, BESS perform better in all three aspects technically, because they do not require a minimum load and can regulate extremely quickly. In practice, however, grid operators often significantly stricter regulatory limits for the permissible power gradients compared to conventional power generation plants. This raises the question for operators of how battery storage systems in load-following operation compare to gas power plants, coal or gas and steam (combined cycle) plants, when considering both technical capabilities and grid-side restrictions.
Technical Advantages of BESS in Load Following Operation
BESS excels in load-following operation due to its unique technical flexibility, which goes far beyond conventional power plants. They achieve a minimum output of 0% – unlike gas-fired power plants (approx. 20%) or coal-fired plants (38–40%) – they can therefore be completely discharged or paused without any downtime. The active power ranges technically from -100 to +100 Pb inst (full charge and full discharge), and power ramps of 10 to 100 %/min feasible, which makes BESS ideal for fast load changes and control power.
These characteristics enable BESS to precisely balance out fluctuations caused by renewable energy sources and promote grid stability. A study by the four transmission system operators from December 2024 shows that battery storage systems could reduce the need for fossil fuel backup power plants by up to 50 % if their full potential is utilized. In practice, however, this is often limited by grid-side constraints imposed by distribution system operators.
Grid operator requirements
Grid operators note that specific restrictions are necessary due to the extremely fast responsiveness or high power ramp of battery energy storage systems (BESS) in load-following operation. Static or dynamic limits must be introduced, especially during high and rapid power fluctuations in the grid, to ensure frequency stability and grid security. Distribution system operators are increasingly adopting such setpoints, for example, in ancillary service markets based on VDE guidelines, in their grid connection agreements. This primarily affects battery storage systems intended to compensate for short-term, impulsive electrical transients in medium and low-voltage grids.
The energy storage industry has already responded critically and calculated that such requirements could reduce BESS market share by up to 50%, as they would diminish revenues from primary control power or load following. This could be mitigated by incorporating dynamic gradients in the calculation models that are adjusted based on grid conditions. Operators should therefore explicitly negotiate with grid operators during the approval process to secure higher quotas.
BESS and conventional power plants in load-following operation compared
Battery Energy Storage Systems (BESS) differ fundamentally from conventional power plants, especially due to their high dynamics and bidirectional flexibility. While classic power plants exclusively produce electricity, BESS can both absorb and release energy – and with very short response times.
Technically, BESS are significantly superior to conventional power plants in load-following operation: They can scale their output with virtually no delay across the entire range from 0 to 100% and achieve power gradients of up to 100% per second. In contrast, gas-fired power plants are physically limited to about 20% per minute and also require a minimum load of around 20%. Coal and combined-cycle power plants react even more sluggishly: lignite plants typically achieve about 3 % per minute at a minimum load of around 40 %, while combined-cycle power plants achieve about 6 % per minute at a minimum load of approximately 33 %.
| Power plant type | Power gradient (1 TP per 6 revolutions per minute) | Minimum credit hours (%) | Power Ramp (MW/min) |
| BESS (Technical) | up to 6,000 | 0 | up to 100 (at 100 MW capacity) |
| BESS (connection limited) | 0,6-10 | 0 | 0,6–10 |
| Gas turbine | 20 | 20 | 20 |
| GuD power plant | 6 | 33 | 6 |
| Coal-fired power plant | 3-4 | 38-40 | 3-4 |
In practice, however, this technical advantage of BESS is often limited by regulatory and grid-related requirements. For example, battery storage systems operating on the grid are sometimes limited to significantly lower power gradients—such as approximately 0.6 % per minute (0.10 % per second)—and are thus subject to stricter regulations than conventional generation plants, which can achieve approximately 0.37 % per second.
Overall, the findings show that while BESS are ideally suited from a technical perspective for balancing the volatility of renewable energies, their potential in grid following operations is not being fully utilized due to current regulatory frameworks.
Optimization & Outlook
In the future, performance gradients are expected to be controlled increasingly dynamically and in a grid-state-dependent manner – for example, based on real-time monitoring of grid load. Forecasts in the context of Network Package 2026 We anticipate that the static limits currently in place can be relaxed by approximately 30–50 % by 2030. As a result, the system-supporting flexibility of BESS will play a central role as a balancing and backup technology for the volatility of renewable energy. In addition, AI-supported optimizations of schedules and ramp rates, as well as targeted Network overlay (e.g., to 150–200 % of connected load) as well as Cable Pooling increasingly important.
Operators can already optimize their systems today through targeted measures:
- Negotiating dynamic network connections:
Under favorable grid conditions, higher power gradients (e.g., >0.20 %/s) may be agreed upon. The regulatory framework—such as that established by VDE FNN—allows for individual deviations in this regard. - Utilize Cable Pooling and Plan Superstructure:
The combination of PV systems and BESS at a grid connection point allows for more efficient use of existing capacity limits, marketing of additional flexibility, and doubling of capacities. - Use intelligent software controllers:
Automated ramp control via EMS with gradient limits ensures compliance with restrictions while simultaneously tapping into revenue potential, for example, in the balancing power market (PRL/FCR). - Avoid minimum load requirements:
Unlike fossil fuel power plants, BESS systems can be shut down to 0–100% capacity without any losses. This eliminates the need to maintain inefficient minimum loads of 20–40%.
Conclusion
BESS dominates the load-following operation despite grid-side limitations due to their superior dynamics and zero minimum load – a clear advantage over fossil fuel power plants. With dynamic agreements, cable pooling, and smart software, they remain economically superior and drive the energy transition forward.
For operators, this means: Act now – optimize grid connections, prioritize balancing power, and negotiate limits. Contact us for an individual BESS flexibility analysis.