Network booster large-scale battery energy storage systems, or utility-scale BESS, which transmission system operators (TSOs) deploy as part of curative system operation to compensate for grid bottlenecks within seconds in the event of a fault. A new procurement concept, the so-called system booster, could purchase this function from market-driven storage facilities for a limited period in the future – instead of building their own systems.
The central difference between a grid booster and a private-sector battery storage system in FTM operation lies not in the technology, but in the Objective and business logic. While an FTM storage system is primarily focused on revenue optimization in the electricity market, a grid booster is deployed specifically to alleviate grid congestion, increase the utilization of existing power lines, and ensure the security of the power system.
What is a grid booster? Definition & functional principle
A grid booster is a large-scale battery storage system that Transmission system operator built at a strategically important network node to enable higher capacity utilization of the existing power grid without compromising security of supply. The concept relies on curative system managementInstead of preventively operating lines at lower capacity to maintain a sufficient reserve in the event of a failure, the grid booster keeps this reserve available in the form of stored energy and is only activated when an actual fault occurs.
The functional principle can be compared to an airbag: if a circuit fails and the remaining lines threaten to become overloaded, the grid booster injects energy behind the bottleneck within seconds while simultaneously absorbing energy in front of the bottleneck. This creates a type of virtual line that relieves the overloaded grid section until conventional redispatch measures or grid expansion take effect. This principle follows the so-called NOVA principle (grid optimization before reinforcement before expansion), according to which German TSOs prioritize optimization measures in the existing grid before building new lines.
Why are grid boosters needed? The North-South bottleneck problem
The expansion of wind energy is concentrated in northern Germany, while major consumption centers and increasingly also power plant shutdowns are located in the south and west. The transmission lines between both regions are already operating at high capacity. To avoid overloads, the TSOs must regularly intervene in power generation. In the event of a Redispatch Before a bottleneck occurs, power plants curtail their feed-in, while facilities downstream increase theirs. These interventions are costly and are passed on to electricity consumers via grid fees. Grid boosters are intended to reduce this demand by allowing existing lines to be utilized at higher capacities without the need to build additional transmission corridors.
Current grid booster projects in Germany
Grid booster projects in Germany are initiated and managed by TSOs. Distribution system operators (DSOs) generally address their own bottlenecks using other instruments such as redispatch 2.0 or Section 14a of the German Energy Industry Act (EnWG). An exception is the project in Bavarian Swabia, where the TSO Amprion is cooperating specifically with DSOs because the facility there can also stabilize the distribution grid. Several other pilot projects are currently under construction or being tested:
- Kupferzell (TransnetBW)With an output of 250 MW and a capacity of 250 MWh, it is one of the largest battery storage projects in Germany. The location was chosen because the power lines between Kupferzell and Grafenrheinfeld are already operating at high capacity.
- Audorf and Ottenhofen (TenneT)Two facilities in the TenneT grid area operating as a North-South pair – Audorf in the north primarily as an energy sink, Ottenhofen in the south primarily as an energy source.
- Bavarian Swabia (Amprion, with DSO participation)Amprion is the lead TSOs, with the DSOs E.ON and LEW involved. They are integrated because the planned 250 MW grid booster can stabilize both the transmission and distribution grids. In phases when there is no need for grid relief, the facility is also fully marketed on the electricity market by the operator.
- Rhinland (AMP-P609)A project confirmed by the Federal Network Agency in the 2037/2045 Network Development Plan consisting of ten decentralized plants of 25 MW each, which could additionally provide instantaneous reserve. In the second draft of the 2037/2045 NDP (2025), it is no longer listed as an independently implemented measure, but rather refers to the possibility of a service tender—the core of the system booster concept described in the following section.
From grid booster to system booster: the new TSO procurement concept
A further development of the grid booster approach is the so-called. System booster. A short expert report published in June 2026 on behalf of Amprion shows that the framework conditions for large-scale battery storage systems have fundamentally changed: falling storage costs and attractive price differentials in the electricity market are leading to strong expansion. Grid connection commitments of around 50 GW are already in place for the German transmission grids.
Instead of building their own TSO grid boosters, these functions could be provided in the future as a system service by market-based large-scale battery storage systems. The storage units would only be deployed as system boosters when needed and, outside of these times, could continue to be marketed commercially on the electricity and balancing energy markets.
The expert report concludes that the benefits of system boosters arise primarily during periods of high wind power feed-in. If their provision is specifically limited to such strong wind situations, the revenue losses for storage operators remain low, whereas a blanket seasonal restriction would be significantly more economically disadvantageous.
Remuneration is to consist of an availability premium as well as an additional payment upon actual activation – similar to the existing balancing energy model. Overall, the expert report concludes that, under suitable framework conditions, system boosters could be more economical than dedicated proprietary grid booster assets. However, the legal framework for this, as well as tenders and planning by the TSOs, are still lacking to date.
Grid boosters/System boosters vs. private-sector FTM storage systems
For front-of-the-meter battery storage operators, a clear distinction is important: Control energy (FCR, aFRR, mFRR) and Current reserve are already today established, permanently accessible marketing channels for BTM storage – regardless of whether the system booster concept is ever implemented. These markets serve frequency control throughout the entire grid area and are an integral part of multi-use commercialization, which many BTM projects already use today.
Grid boosters and system boosters, on the other hand, function fundamentally differently: they are not focused on frequency maintenance, but rather on the local, curative resolution of specific transmission bottlenecks targeted at specific grid nodes and requested on a situational basis—such as in the case of a system booster when wind power injection is high. Therefore, this is not an alternative to the existing balancing energy and inertia marketing, but potentially a additional, optional revenue component for large-scale battery energy storage systems already connected to the transmission grid. The short expert report by Amprion makes an important qualification in this regard: it considers a direct grid connection to the transmission grid to be necessary because, in the event of activation, there is no time available for coordination with distribution system operators. For projects at the distribution grid level, the system booster therefore remains irrelevant for the time being.
Direct comparison
| Grid booster (TSO-owned) | System booster (market-based, temporary) | Private BESS with grid services (FCR / aFRR / mFRR) | Private BESS for synthetic inertia | |
| Main purpose | Local relief of grid bottlenecks, support for the transmission grid | Same function, temporarily acquired | Stabilization of system frequency and power balance | Very fast initial stabilization after disturbances |
| Owner / Operator | TSO | Private storage operator, on behalf of the TSO | Private operator | Private operator |
| compensation logic | TSO-funded investment – internal to TSO | Retention bonus + opportunity cost and capitalization compensation | Market-based tender/ auction | Market-based tender/ auction |
| Spatial reference | At specific points, at a specific network node or bottleneck | At network nodes or close to regional network nodes | System-wide or control zone-wide | System-wide, effective very short-term |
| Trigger | Imminent line overload or network bottleneck | equal: in case of impending capacity limits or bottlenecks | Frequency deviation or balance imbalance | Major disturbance, sudden power deficit/surplus |
| Time Horizon | Seconds to minutes, depending on the network situation | immediately: seconds to minutes, depending on network conditions | FCR very fast, aFRR and mFRR downstream | Immediately to very shortly after the event |
| Commitment period | Long-term (multi-year) | Possible in the short term (e.g., 1 year) | Running | Running |
| procurement logic | From a grid operator's perspective, beneficial to the grid, often conceived as regulated infrastructure | t.b.d.: Not yet defined | Market-based through tenders and call-offs | Depending on the system design, more in terms of network engineering/physics rather than a classical market mechanism |
| Economic logic | Avoidance of redispatch and grid expansion costs | Reduction of TSO investments + avoidance of redispatch and grid expansion costs | Revenue from provision and activation | Safety feature, not primarily a commercial product |
| Status | In construction/operation (pilot projects) | Conceptual study, no call for bids in sight | Established market | market since 2026 |
| Can a battery storage system do that? | Yes | Yes | Yes | Yes, upon technical and regulatory approval |
System booster as a new revenue source for FTM BESS operators?
If the system booster concept actually reaches the stage of being tendered, it would create an interesting new revenue source for operators of large FTM storage systems connected to the transmission grid: an additional, predictable remuneration component that would exist alongside balancing energy, instantaneous reserve, and market trading without displacing these existing revenue streams. Precisely because the expert report shows that losses in revenue can be kept low with wind-based rather than seasonal availability, the system booster would potentially be associated with a comparatively low sacrifice in market revenues. For today's investment decisions, this is not yet a viable component—but it is an aspect that project developers and investors should keep in mind when choosing locations connected to the transmission grid.
Regulatory status and classification
The system booster concept is currently only a proposal from the Amprion expert opinion and not an adopted regulation. Open issues include, among other things, the cost reimbursement methodology in redispatch, the remuneration logic outlined in the expert opinion, which the TSOs cannot yet fully map, as well as a penalty concept yet to be developed for insufficient availability when requested.
Implications for BESS Operators & Energy Managers
For operators and investors of FTM battery storage systems connected to suitable transmission grid nodes, it is particularly worthwhile to keep an eye on the development of the system booster concept: Should a tender take place, an additional revenue component would be created that complements the existing multi-use marketing via balancing energy and intraday markets without replacing it. In the short term—that is, for current investment decisions—the focus remains on established revenue sources such as balancing energy, instantaneous reserve, and flexibility marketing.
FAQ about Grid Boosters & System Boosters
What is the difference between grid booster and system booster?
Not yet in the form of an ongoing tender. As of summer 2026, the system booster concept is a proposal from a brief expert report; concrete procurement has not yet been implemented.
Can residential battery storage systems already act as grid boosters today?
Not yet in the form of an ongoing tender. As of summer 2026, the system booster concept is a proposal from a brief expert report; concrete procurement has not yet been implemented.
Is participation in grid booster or system booster marketing already possible?
No, not currently. Established and accessible by contrast are the balancing energy markets (FCR, aFRR, mFRR) as well as the marketing of instantaneous reserve, which exist independently of the system booster concept.
What do FTM storage operators earn from grid services today?
Balancing energy and instantaneous reserve marketing are established, continuously accessible revenue sources for FTM large-scale battery storage systems and part of a typical multi-use marketing strategy – regardless of the grid booster topic.