On October 17, 2025, the Federal Network Agency published FAQs on the regulatory treatment of stationary battery storage systems (“BESS”). The FAQs are a guide for storage system operators, as the grid connection process and the operation of storage systems create legal uncertainties for them. The explanations are not legally binding, but can be used to standardize application practice and interpret existing regulations. However, there are still many unanswered questions that storage and grid operators must clarify in individual agreements. In the following, we classify the central statements of the FAQs from a legal perspective.
1. applicability of the KraftNAV for large battery storage systems leads to discrepancies in the grid connection procedure between the feed-in and withdrawal sides
The Federal Network Agency confirms: The Ordinance on the Regulation of the Grid Connection of Installations for the Generation of Electrical Energy (KraftNAV) applies to large-scale battery storage systems on the feed-in side. This applies to storage facilities with a capacity of 100 MW or more and with a connection at transmission grid level. In view of the dual role of storage facilities – consumer and producer – this classification has a number of consequences.
Tightly meshed grid connection procedure prescribed by law for storage systems on the feed-in side
The KraftNAV imposes clear deadlines and obligations on the grid operator for the grid connection on the feed-in side of storage facilities. For the storage operator, this means – at least in theory – planning security and transparency. From the grid operator’s point of view, compliance with the deadlines of the KraftNAV, which was originally created in 2007 for conventional power plants, appears to be almost impossible to implement. This poses a considerable implementation risk. The Federal Council only came out in favor of removing storage facilities from the scope of the KraftNAV in mid-September 2025.
However, if one follows the Federal Network Agency and applies the KraftNAV, the grid operator must inform the storage system operator requesting the connection within two weeks, for example, which tests are necessary to prepare its decision and what costs are incurred as a result.
In the event of a positive decision on the grid connection request, the grid operator is obliged to issue a binding connection commitment to the connection recipient. This commitment includes the reservation of the grid connection capacity at a specific grid connection point. However, the connection commitment only becomes effective if the connection recipient pays a reservation fee of EUR 1,000 per megawatt of grid connection capacity and the costs for the previous inspection within one month of receiving the commitment. The fee remains with the grid operator and is offset against its claims for reimbursement of costs incurred in establishing the grid connection.
The reservation fee will be refunded if the grid connection cannot be established for reasons that are not the responsibility of the storage system operator. An example of this would be the unexpected rejection of an official permit that was considered certain.
Furthermore, the applicability of the KraftNAV means that storage system operators do not have to pay a construction cost subsidy on the feed-in side. However, this cannot be transferred to the withdrawal side, as the BGH clarified in its ruling of July 15, 2025 (EnVR 1/24).
Prevent double charging of storage operators through agreement with grid operators
If a separate grid connection procedure is to be carried out on both the feed-in and offtake side, different processing speeds may occur. This is due to the fact that the KraftNAV stipulates short deadlines by law on the feed-in side. However, it remains questionable whether these deadlines can be met by the grid operators given the high number of connection requests. In contrast, the grid connection procedure on the extraction side is only rudimentarily regulated in the Energy Industry Act; in particular, there are no specific deadlines.
In addition, a separate procedure may lead to two reservation fees and the construction cost subsidy on the withdrawal side having to be paid. Storage system operators should therefore negotiate a suitable agreement with the grid operators.
The application of two differently regulated procedures for one and the same system therefore poses challenges for operators of large-scale battery storage systems. The four German transmission system operators have already announced that they will develop solutions. They are planning to create largely standardized process steps, coordinated scopes of services and cost contributions for storage operators.
2. more transparency in the grid connection procedure on the withdrawal side: Federal Network Agency requires grid operators to provide specific information to those requesting a connection
The processing of connection requests by grid operators often takes a long time. The reason for this is, on the one hand, the high number of grid connection questions and, on the other hand, the lack of a legal definition of the grid connection procedure on the withdrawal side. It is encouraging that the FAQs are working towards more transparent communication between grid operators. This enables storage system operators to reduce planning risks and financial losses, as they can better assess the likelihood of their projects being realized.
The FAQs stipulate that applicants must provide information on the availability of and the procedure for distributing grid connection capacity (first-come, first-served, first-ready, first-served), among other things. In addition, grid operators should respond immediately to inquiries about the feasibility of a connection at the desired grid connection point. However, this obligation must be viewed in context. In the legal sense, the term “without delay” means “without culpable hesitation” and should not be interpreted as “immediately” in view of the congestion of network operators.
A clear time sequence for the provision of information is still not guaranteed. Storage system operators should also be aware that the information obligations are not enforceable. Nevertheless, it may make sense to draw the network operators’ attention to the obligations and actively urge them to provide the information.
3. the BNetzA creates partial certainty regarding the fate of realization deposits
Implementation deposits are not regulated by law. The Federal Network Agency has now confirmed that grid operators may demand a realization deposit as a precondition for an application review. The deposit can be charged at the beginning of the process and must therefore be distinguished from the reservation fee under the KraftNAV. The latter may only be demanded after a connection commitment has been issued.
At first glance, the implementation deposit may appear to be a financial hurdle for storage system operators, but it offers decisive advantages. The deposit prevents the blocking of grid connection and processing capacities, which is in the interest of serious connectees. It acts as a filter mechanism that helps grid operators to allocate resources more efficiently and prioritize serious projects. This shortens the waiting times for such projects.
The Federal Network Agency does not consider a realization deposit of 1,500 euros per megawatt of grid connection capacity to be unreasonable. For a project with 50 MW, the deposit could amount to EUR 75,000; for a larger project with 200 MW, it would be EUR 300,000.
Important for storage system operators: The sum cannot be lost through no fault of their own. The Federal Network Agency has now clarified this for three scenarios:
- Realization of the project: The deposit is credited against the construction cost subsidy and/or connection cost contributions and remains with the network operator.
- Non-realization regardless of the actions of the subscriber: The deposit is refunded.
- Non-realization for reasons of the subscriber: The deposit is forfeited.
If the project is successfully realized, the deposit is therefore offset against subsequent payments. Storage system operators should agree with the grid operators the conditions under which the deposit will be retained or refunded in order to guarantee planning security for investors. This is because the reasons falling within the risk sphere of the subscriber can be manifold.
4. differences in the amount of the building cost subsidy are permissible if objectively justified
Since the decision of the BGH on July 15, 2025, it has been clear that storage system operators must pay a construction cost subsidy if the grid operator charges one as a matter of principle. There is no obligation to charge. However, the question of possible reductions remains a key issue in the industry, as subsidies for large battery storage systems can amount to several million euros.
It is striking that the Federal Network Agency initially does not want to allow any blanket reductions on the construction cost subsidy, but then goes on to allow exceptions. This appears contradictory. Two possibilities for reductions are listed:
- Objectively justified differentiations: These may exist if the grid operator can restrict the storage facility’s access to the grid at certain times on the basis of contractual agreements.
- Flexible grid connection agreements (“FCA”): These are agreements between the grid operator and the subscriber on flexible power limits for feed-in or withdrawal.
In addition, further reductions in the construction cost subsidy appear possible. In the transmission grid in particular, reduced subsidies are levied in some cases if the siting of a storage facility or another end consumer causes less or no additional costs from the perspective of the grid at a particular location. The construction cost subsidy could even be waived completely if the storage facility is operated in a way that is beneficial to the grid. This is indicated by the BGH decision of July 15, 2025.
