Standardised Metering Concepts for Battery Storage and V2G

E-Control is currently consulting on the TOR Metering Regulation. The draft (2.0) addresses, for the first time, metering concepts for battery storage and the treatment of bidirectional charging facilities (V2G/V2H/V2B), establishing – subject to final adoption – standardised framework conditions for market participants.

The key innovations relate to standardised metering concepts for installations with electrical energy storage systems – a topic of high practical relevance for energy suppliers, plant operators and project developers. According to the draft, uniform definitions for operating modes (grid consumption/grid feed-in/V2X), metering points and GO (Guarantee of Origin) treatment will be established, intended to provide planning certainty for billing, metering and subsidy logic. Standardised metering concepts can also reduce implementation and transaction costs for projects (generation plants and BESS) and transform M&A risks from intangible grey areas (individual metering setups) to documentable target/actual comparisons along clearly defined configurations and variants (thereby reducing the effort required for valuation, contract drafting and integration).

Comments can be submitted until 10 June 2026.

Overview: What is Changing?

The new version 2.0 is now based on the Electricity Industry Act (ElWG) as successor to the former ElWOG 2010. The scope continues to cover the minimum requirements for metering equipment (Section I) and – as a key innovation – the definition of standardised metering concepts (Section II). A particular focus is placed on metering concepts for customer installations with electrical energy storage systems (battery storage); the metering treatment of bidirectional charging facilities in the context of Vehicle-to-grid (V2G) and Vehicle-to-home/building (V2H/V2B) is also addressed. Key innovations also include the integration of the “Split Supply” aggregation model, the regulations on energy communities and shared energy use pursuant to §§ 66 to 68 ElWG, and consideration of the KenV Amendment 2025.

Grid users shall have a right to standardised metering concepts vis-à-vis grid operators. The use cases cover new or substantially modified installations with electrical energy storage systems and/or hybrid power generation plants, existing installations for which a standardised metering concept is to be applied at the request of the grid user, and installations with separate billing points for consumption facilities (equipment pursuant to § 98 ElWG). Grid operators and grid users are also entitled to agree on alternative metering concepts in justified cases, provided these comply with all regulatory requirements.

Focus: Operating Mode of Electrical Energy Storage

The operating mode of the energy storage system is of central importance for the applicable metering concept. A distinction must be made between two key criteria:

• Charging with grid consumption: Charging with grid consumption occurs when the charging power of the storage system exceeds the simultaneous total output of all power generation plants within the same customer installation; in other words, when more is stored than the power generation plants produce at the same time.
   
• Grid feed-in from storage: Grid feed-in from storage occurs when the instantaneous feed-in power at the main metering point exceeds the simultaneous total output of all power generation plants; in other words, when more is fed into the grid than the power generation plants produce at the same time. If the storage controller or energy management system can reliably prevent this, the entire grid feed-in is attributed to the power generation plants.

For both operating modes, control based on measured values with a resolution in the second range is decisive, which typically requires an EMS/controller setup with second or sub-second measurement. Control with a resolution of quarter-hourly values is expressly not sufficient. Ensuring suitable control is the responsibility of the grid user. The grid operator is entitled to request confirmation from the executing electrical contractor regarding the implementation of the required technical measures for capturing the measured values.

The draft describes a total of eleven plant configurations for customer installations with electrical energy storage systems (S1 to S11). In addition to the composition of the customer installation, the operating mode of the energy storage system (see above) is decisive for the respective metering and calculation concept. The configurations are systematised by increasing complexity, with grid feed-in from storage and storage charging with grid consumption being the central distinguishing features.

Overview of the key configurations:

• Configuration S1 (Stand-alone storage without generation/consumption): For pure storage installations without power generation or consumption facilities. For storage systems from 250 kWh, a Guarantee of Origin storage account (cf. below “GO-Storage-Account”) is maintained; for storage systems below 250 kWh, Guarantees of Origin are cancelled.
   
• Configuration S2 (Storage used solely for optimizing self-consumption, with no feed-in to the grid; may be used as integrated storage): The storage serves exclusively for self-consumption optimisation and does not feed into the grid. No GO-Storage-Account is maintained. Electrical energy storage systems that are charged exclusively by a power generation plant behind the same metering point may be regarded as an integral part of that power generation plant (“integrated electricity storage”). The prerequisite is that technical measures ensure that no storage charging occurs through consumption from the public grid or from power generation plants other than the one assigned to the storage system. The same applies to storage systems that are to be regarded as an integral part of a consumption facility, provided no feed-back into the public grid or supply to other parts of the installation occurs.
   
• Configuration S3 (Storage and consumption facilities): Below 250 kWh, no GO storage account is maintained; from 250 kWh, a GO-Storage-Account must be maintained.
   
• Configurations S4 and S7 (Storage without grid consumption): The storage is charged exclusively with self-generation; it is contractually agreed that charging with grid consumption is reliably prevented by the storage controller or energy management system. The storage is considered “integrated electricity storage” and no GO-Storage-Account is maintained. These configurations are EAG or ÖSG compatible.
   
• Configurations S5, S8 and S11 (Storage with grid consumption and grid feed-in): Subsidies pursuant to EAG or ÖSG are generally not applicable in these configurations, as a demarcation of the eligible electricity quantity is not possible. For S5, eligibility for subsidies must be considered on a differentiated or case-by-case basis.

Depending on the plant configuration, there are three possible variants of the metering and calculation concept:

• “Flat-rate calculation”: In this variant, the storage consumption quantities for the GO storage account are estimated based on the round-trip efficiency of the storage system. If the grid user has not credibly demonstrated a plant-specific efficiency to the grid operator, a technology-specific reference value must be used (§ 10(2) KenV Amendment 2025).

Relevant metering concepts: Storage configurations S3 (variant < 250 kWh and ≥ 250 kWh), S5 and S8; for S8, however, without EAG/ÖSG subsidy and without separate supply/aggregation contracts.

• “Surplus feed-in”: In this variant, the feed-in quantity measured at the main meter is used for billing and clearing. This variant is expected to be useful when simple setups do not require separate billing.

Relevant metering concepts: Not intended for storage configurations S1–S11; relevant only for metering concepts in connection with power generation plants, specifically H2 and A1–A4 (each depending on the variant in the individual case).

• “Virtual separation”: In this variant, the sub-meter values are used unchanged for billing and clearing; the residual consumption is the difference between the balance of the main meter values and the balance of the sub-meter values. This variant is expected to be useful when exact demarcation of plant components is necessary (e.g. Split Supply). 

Relevant metering concepts: Storage configurations S3, S5 and S8; for S8, no subsidy pursuant to EAG or ÖSG is permissible.

In principle, the grid user has freedom of choice for plant configurations for which several variants are described. However, case-specific restrictions must be observed: The “Virtual separation” variant is only permissible for power generation plants receiving subsidies pursuant to EAG or ÖSG in configurations without consumption facilities. For installations with energy storage systems, simplified metering concepts may apply in some cases if the energy storage system has a capacity below 250 kWh. For storage configurations S1 (stand-alone storage) and S2 (storage exclusively for self-consumption optimisation, without grid feed-in), no variants are provided; the respectively defined, variant-free metering concepts apply.

GO-Storage-Account: 250 kWh Threshold

The provisions on the Guarantee of Origin system for storage are linked to the threshold of 250 kWh storage capacity. For storage systems from 250 kWh, a GO storage account is maintained pursuant to the KenV Amendment 2025; Guarantees of Origin in the amount of the energy stored per calendar month must be transferred to a storage account once a year. For storage systems below 250 kWh storage capacity and bidirectional charging facilities for electric vehicles (regardless of storage capacity), the exceptions pursuant to § 86(8) ElWG apply. For the applicability of these exceptions, the sum of the storage capacities of all storage systems within the entire customer installation is decisive.

Vehicle-to-Grid (V2G) and Vehicle-to-Home/Building (V2H/V2B)

With the ElWG, bidirectional charging facilities for electric vehicles are addressed at the legislative level for the first time. TOR Metering Version 2.0 now implements this new legal framework in terms of metering technology and integrates V2G and V2H/V2B use cases into the standardised metering concepts.

In the context of the metering concepts, bidirectional charging facilities with vehicles are always considered storage systems that are charged with grid consumption (see Section 9.2 “Operating mode of an electrical energy storage system”). The central distinction lies in the grid impact: With Vehicle-to-grid (V2G), grid feed-in from storage (i.e. the vehicle) occurs; with Vehicle-to-home/building (V2H/V2B), it does not – in this case, the stored energy is consumed exclusively within the customer installation. Since bidirectional charging facilities are always classified as “charged with grid consumption”, those plant configurations apply to V2G applications where both storage charging with grid consumption and grid feed-in from storage are present (in particular S1, S3, S5). This has immediate consequences: A shared feed-in metering point with an EAG or ÖSG-subsidised power generation plant is not permissible for V2G, as the energy quantity originating from the power generation plant cannot be distinguished from fed-back grid consumption.

With regard to the Guarantee of Origin system, the exceptions pursuant to § 86(8) ElWG or the KenV Amendment 2025 apply to bidirectional charging facilities – regardless of the connected storage capacity of the vehicle. The consumption from the grid is fully valued as end consumption, even if part of the consumption is fed back into the grid at a later point in time. No Guarantees of Origin are generated for a feed-in metering point established specifically for the charging facility. This represents a considerable simplification compared to stationary storage systems from 250 kWh, for which a GO storage account must be maintained.

Outlook and Recommendations

The consultation draft contains comments and explanations that have been included for better comprehensibility and will not be included in the final version. Affected market participants – in particular energy supply companies, plant operators and project developers in the field of renewable energies – should use the consultation period to familiarise themselves with the draft and submit any comments.

Particular attention should be paid to the choice of operating mode (charging with or without grid consumption), the effects on eligibility for subsidies pursuant to EAG/ÖSG, and the requirements for second-level control.

The consultation draft can be found at: Current Draft Reviews - E-Control

Please do not hesitate to contact CMS experts if you have any questions.