Bidirectional Charging and V2G: Germany's MiSpeL Breakthrough

Why bidirectional charging becomes economic

Bidirectional charging turns the electric car into a storage unit that not only takes in power but also gives it back. With V2H (vehicle-to-home) the car battery supplies the building, with V2G (vehicle-to-grid) it feeds back into the public grid, and with V2L a single device runs directly off the car. The technology has existed for years. What was missing was the economic basis.

The reason was plain and expensive. Anyone who charged grid electricity into a car battery and fed it back later paid network charges and levies twice, once when charging and once when using the power again. This double burden made vehicle-to-grid unprofitable for most households and fleets and left Germany one of the most restrictive markets in Europe until 2025.

In 2026 that turns around. The Federal Network Agency adopted its ruling on the market integration of storage and charging points, MiSpeL for short, on 1 October 2026, and since December 2025 an amendment to the Energy Industry Act has ended the double burden of network charges. A technical promise becomes a product you can calculate. For energy utilities, municipal utilities and aggregators this is more than a detail, because every plugged-in vehicle becomes a small, controllable storage cell in the system.

A typical car battery holds several times the capacity of a usual home storage unit. It is only available when the vehicle is plugged in, which on average it is for most of the day. Exactly those hours at the grid are the raw material for the new flexibility models, which borrow the logic of virtual power plants.

The double-burden problem and how it is solved

Two rules stood in the way. When a vehicle charged grid power and fed it back later, that grid offtake carried levies and network charges although the power only passed through the car; whoever then used it from the grid paid them a second time. And anyone running a subsidised solar system lost the support for storage feed-in under the exclusivity option as soon as grid power entered the storage unit; bidirectional charging points were not provided for at all. For the owner too little was left to justify a wallbox and a suitable vehicle.

Network charges were solved by the EnWG amendment the Bundestag passed on 13 November 2025. The act of 18 December 2025 (Federal Law Gazette 2025 I No. 347) has applied since 23 December 2025 and rewrites Section 118(6) sentence 3 EnWG: the network-charge exemption applies insofar as the power flows back into the same grid with a time lag, and Section 21 EnFG applies accordingly. Through this reference bidirectionally used charging points are treated like storage, because Section 21(3) EnFG puts them on a par with storage for the levies. The exemption under Section 118(6) covers storage commissioned by August 2029, for 20 years each.

Which volumes are exempt follows, in the Federal Network Agency's reading, from the MiSpeL formulas, because the reference to Section 21 EnFG includes how MiSpeL shapes it. The agency treats the reference as a transitional rule until the end of 2028. From 2029 the AgNes ruling is to govern network charges for storage and charging points, and whether it keeps referring to MiSpeL will be decided there, not in MiSpeL.

One clarification keeps the terms clean. The old EEG levy has not existed since July 2022 and does not return here. MiSpeL is about the EEG eligibility of fed-in electricity and about the EnFG levies, so not the old levy but the correct allocation of renewable and grid power. Network charges themselves are governed by the EnWG, and the ongoing reform of the network charge system AgNes forms the larger frame in which this exemption sits.

What the MiSpeL ruling sets out: options, metering, duties

MiSpeL (ref. 618-25-02) consists of the operative part with its reasoning, Annex 1 on the demarcation option and Annex 2 on the flat-rate option, about 250 pages in all. It shapes two areas of law: the market premium for the eligible share of feed-in under Section 19(3b) and (3c) EEG, and the levy privileges under Section 21 EnFG for grid power that is stored and fed back. MiSpeL does not set network charges itself; they hang on Section 21 EnFG through a statutory cross-reference, as described in the section above.

Until the ruling, storage at a subsidised plant only had the exclusivity option under Section 19(3a) EEG. It requires that only renewable power is stored during the whole calendar year; once grid power flows into the storage unit, support for feed-in from storage is lost for the entire year. Bidirectional charging points cannot use this option at all, because an electric car also brings power charged elsewhere. MiSpeL keeps the exclusivity option and adds two options in which storage units and charging points may charge grid power, feed in according to market prices and still keep the support for the solar share.

No MiSpeL option without direct marketing

Operative point 5 holds the condition with the biggest consequences. Anyone who wants the market premium under the demarcation or the flat-rate option assigns at least one renewable plant plus the storage units and bidirectional charging points behind the feed-in point to direct marketing with market premium, and states which option is used; assignment and switching follow the rules on the form of sale in Sections 21b and 21c EEG. With a fixed feed-in tariff only the exclusivity option remains. Consultation participants such as DGS and DIHK asked for the feed-in tariff to be allowed; the Federal Network Agency refuses, citing the wording of the law: the options are meant to steer feed-in and grid offtake in the quarter-hour rhythm of the market, and under the feed-in tariff there is neither a price signal nor a direct marketer to respond to it. A small solar system on the feed-in tariff therefore has to move to direct marketing before its storage unit or wallbox may charge grid power without putting the support at risk. Plants without support use MiSpeL through unsubsidised, other direct marketing under Section 21a EEG.

Demarcation option: any system size, own meter, monthly netting

Under Annex 1, the demarcation option applies to plants of every type and size, including purely grid-connected storage and sites with no generation of their own. Storage units and charging points are metered separately, with at least two meters in base cases A1 to A4. From the quarter-hour values, fixed formulas work out which share of the feed-in is eligible and which grid offtake is relieved of levies. The basis is a statutory storage priority (Section 21(4) EnFG): if grid power is drawn and the storage unit charged in the same quarter hour, the grid power counts as stored, and if power is fed in while the storage unit discharges, the storage output counts as fed in. Volumes are determined per calendar month, the netting period is the month, and the annual statement adds up the monthly values; in the consultation draft it was still the year.

Annex 1 is built as a toolkit of formula sets A1 to A11. Besides the base cases with storage, charging point or both, there are special cases for several renewable plants, an additional generating plant, a separately supplied heat pump, co-located storage next to a ground-mounted solar or wind plant, grid offtake with different levy rates as under the special equalisation scheme, purely grid-connected storage (A10) and storage or charging points without any other generation (A11), where a single meter is enough. A simplified formula set may only be used where the metering for the more precise one is missing, and the chosen formula set generally applies for the whole year. Stationary storage can also take part of its storage losses out of the levies, as far as the losses stem from arbitrage operation; for charging points the losses of the vehicle battery count as driving power.

Flat-rate option: solar up to 30 kW, one quarter-hour meter, annual settlement

Annex 2 sets out the flat-rate option, the simplified route for sites where nothing generates except solar systems of no more than 30 kilowatts in total plus storage units and charging points, all run by one operator (Section 19(3c) EEG); plug-in solar devices do not count towards the 30 kilowatt limit. Instead of separate meters, one bidirectional meter at the house connection that records feed-in and offtake per quarter hour is enough, and the meter cabinet does not need rebuilding. Settlement is a flat calculation for the calendar year. Feed-in is eligible up to 500 kilowatt-hours per kilowatt of solar capacity, so up to 5,000 kilowatt-hours a year for a 10 kilowatt system. Feed-in is only relieved of levies above a second threshold, the flat-rate netting limit, and whatever lies between the two counts as indifferent: it is neither supported nor netted. Storage losses cannot be credited separately in the flat-rate option.

How wide this indifference band turns out depends on the ratio of storage capacity to solar capacity. For a 10 kilowatt system with a 10 kilowatt-hour storage unit, Annex 2 gives a netting limit of about 5,500 kilowatt-hours a year, with 4 kilowatt-hours of storage about 6,250. If only a bidirectional charging point without stationary storage sits at the house connection, the ruling applies a fixed factor of 0.2, down from 0.5 in the earlier version, which narrows the indifference band for charging points considerably. The limit is meant to stop solar power from receiving a second subsidy through the levies and network charges paid by other grid users. Anyone who wants to net more at a charging point can use formula set A2 of the demarcation option with two meters instead of the flat rate. The flat-rate option only applies to feed-in from the calendar month after the European Commission grants state aid approval for Section 19(3c) EEG (operative point 9(b)).

What applies to bidirectional charging points

MiSpeL assigns charging and feeding back to the charging point, not to the car (Section 19(3) sentence 5 EEG, Section 21(3) EnFG). Any bidirectional vehicle can therefore take part at any bidirectional charging point, with no meter in the vehicle. Both V2G and V2H are covered as soon as power can flow back into the grid through the charging point; a wallbox that can only charge counts as ordinary consumption. MiSpeL draws two lines. Driving power, meaning everything the car uses for driving and operation including its battery losses, bears levies and network charges like any other consumption in the house. And power the car charged elsewhere, at the employer for instance, gets no EEG support as "external charging power": the demarcation option deducts it when more comes out of the charging point in a month than went in; with the single meter of the flat-rate option it cannot be detected.

In both options the market premium is only paid for quarter hours in which the applicable value has not dropped to zero, as happens at negative exchange prices under Section 51 EEG. Annex 2 goes one step further and does not net feed-in at negative spot prices against the levies either. Feeding in from storage or car in such quarter hours therefore earns no support.

Who has to do what

Claiming the levy reduction falls to the grid user within the meaning of the EnFG, usually the electricity supplier of the household or business. The plant operator claims the market premium, mostly through its direct marketer, and feed-in is balanced per quarter hour, in the flat-rate option in a separate direct-marketing balancing group or sub-balancing group. Under operative point 7 grid operators and metering operators must enable both options; until 30 September 2027 this only works with their consent, from 1 October 2027 also without it. Anyone using the levy privileges has to meet the notification duties under Part 5 EnFG (Section 21(4) EnFG), for storage and charging points by 31 May of the following year (paragraph 7). For the 2026 levies that is 31 May 2027.

The timeline: ruling in 2026, transition until 2027

The ruling came later than the law required. Under Section 85d of the Renewable Energy Act the Federal Network Agency should have adopted it by 30 June 2026; it did so on 1 October 2026. A day later it presented the final version at a workshop.

Legally the field has been open since 21 October 2026, in practice not yet everywhere. Until the end of September 2027 every site depends on the consent of its grid operator and its metering operator. After that both are obliged to enable the options (operative point 7). Operators who set up metering and billing early can accept requests during the transition period instead of putting them off until autumn 2027.

Technical conditions: standard, connection rule, vehicles

For vehicle-to-grid to work in daily use, vehicle, wallbox, meter and grid connection have to match. The ISO 15118-20 standard governs the bidirectional data exchange between vehicle and charging point and is the basis for bidirectional charging and Plug and Charge in Europe. ISO published it in April 2022.

On the grid side, the VDE-AR-N 4105 connection rule in its 2026-03 edition, published on 26 February 2026, sets requirements and proof for feed-back-capable charging equipment for the first time: it counts as storage within the meaning of the rule as long as a feed-back-capable vehicle is connected. Grid operators and installers now know which rules apply when such a wallbox is connected and later steered through a low-voltage control system; VDE FNN did not, however, work its guidance note on bidirectional charging into the new edition. The wallbox itself is a controllable consumption device whose grid-friendly control is already governed by Section 14a of the EnWG.

On the vehicle side the choice is growing slowly. Models such as the BMW iX3 of the Neue Klasse, several models of the VW ID range with a large battery, the Renault 5 and the Nissan Leaf via the older CHAdeMO standard support bidirectional charging. BMW and E.ON launched the first commercial V2G offer in Germany in February 2026, initially only for the iX3, with an 11 kilowatt DC wallbox and a smart meter as a precondition. In October 2026 Mercedes-Benz and The Mobility House Energy presented an offer for the GLC and the new C-Class, also using an 11 kilowatt DC wallbox. Bidirectional AC wallboxes under ISO 15118-20 have so far only been demonstrated, by Bender for example. Series readiness is here, and the market stands at the start of its ramp-up. That wallboxes reach buildings at all is also driven by the GEIG amendment.

What it delivers: economics and grid value

The value works on two levels. For the owner, the end of the double burden makes V2G calculable for the first time. Solar power can be used at any hour, load shifted into cheap hours and feed-back remunerated. Separately from V2G, the wallbox as a controllable consumption device gets a flat network-charge reduction under Section 14a module 1, which the Federal Network Agency put at 110 to 190 euros gross a year depending on the grid area in 2023. In many cases the vehicle replaces part of what would otherwise need a separate home storage unit.

For the energy system the sum is what counts. Every plugged-in vehicle becomes a small, flexibly callable storage cell that can relieve local bottlenecks and buffer generation peaks from wind and sun. This is exactly the decentralised flexibility the grid needs as the share of renewable generation grows.

For energy utilities and aggregators this opens a new flexibility market. Whoever bundles many vehicles can smooth peaks, offer balancing energy and back dynamic tariffs with real storage behaviour. The principle resembles a virtual power plant, except the storage units stand on wheels and hang on the grid at changing places during the day. Which digital business models this opens up is set out in the piece on Vehicle-to-Grid as a business model.

What energy utilities and aggregators should do now

The entry works best along the billing and data processes, not through technology alone. The regulatory clarity is here, the vehicles and wallboxes are coming, and the real bottleneck now lies in the systems that bring metering, market communication and tariff together cleanly.

Four steps order the start. They interlock but can each begin independently.

1. Prepare billing and IT

   Grid and metering operators have to handle both options without case-by-case consent from 1 October 2027. By then the quarter-hour values at the house connection and at the storage or charging point meter, the formula sets of Annexes 1 and 2 and the assignment to direct marketing belong in billing and market communication. Suppliers build the levy netting and the notification by 31 May of the following year into their processes.

2. Test a V2G tariff

   Set up a V2G or V2H tariff with transparent remuneration for feed-back and a link to a home energy management system, and trial it with a small group of customers. Plan the direct marketer in from the start, because neither MiSpeL option works without direct marketing.

3. Bundle flexibility

   Build vehicle pools as an aggregate and make them usable for balancing energy and grid-friendly control, with clear rules for availability and remuneration.

4. Anchor standards

   Fix ISO 15118-20 and VDE-AR-N 4105 in procurement and gather experience from pilot projects early, instead of learning every lesson alone.

Bidirectional charging is therefore less a single product than a building block of the digital energy transition. Its value emerges only in the interplay of regulation, metering, tariff and control. Whoever connects these threads early is ready when the transition period ends in late September 2027.

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