Vehicle-to-Grid

Vehicle-to-Grid (V2G) allows an electric vehicle (EV) battery to discharge electricity back into the grid via a bidirectional charger, turning the EV into a mobile distributed energy resource. V2G is a subset of the broader Vehicle-to-X (V2X) concept — bidirectional power transfer from an EV to any external system.

V2X taxonomy

(Source - Power Circle V2X Synthesis 2024)

V2H is widely viewed as a gateway product for V2G adoption — consumers experience direct, immediate financial benefit (self-supply) before engaging with the more complex grid services market. (Source - KTH Thesis V2G Sweden 2024)

How V2G works

Hardware: a bidirectional charger (wallbox or EVSE) capable of both charging (G2V, grid-to-vehicle) and discharging (V2G). An inmatningsabonnemang (grid injection subscription) is required at the connection point to export electricity to the grid.

AC vs DC:

• AC bidirectional: inversion (AC↔DC) happens inside the vehicle’s on-board charger (OBC); wallbox is cheaper; but AC V2G communication protocols are less mature — the AC standard does not include state-of-charge data in the standard communication layer
• DC bidirectional: inversion in the external charger; wallbox is more expensive; better protocol maturity for communication between charger and grid systems

Communication standards:

• ISO 15118-20 — bidirectional charging protocol for vehicle–charger communication; the enabling standard for V2G at the charging interface; operates during the Usage phase (EV connection, authentication, negotiation of charging/discharging parameters)
• OCPP 2.1 (Open Charge Point Protocol) — charger-to-backend communication protocol; enables aggregation platforms to control and monitor charging sessions; also used at the Installation/Configuration phase for remote EVSE setup before the service goes live
• OpenADR / IEEE 2030.5 — used during the Usage phase to carry demand response signals and dynamic pricing from Aggregator platforms to EVSE/DER systems
• IEC 61850 — grid infrastructure standard used in backstage coordination between Aggregator platforms and DSO/TSO control systems

(Source - Power Circle V2X Synthesis 2024, Source - Malakhatka et al V2G Service Blueprint Sweden (2026))

Grid services V2G can provide

Swedish market potential

(Source - Power Circle V2X Synthesis 2024, Source - FlexAbility Delrapport 1 (2025))

The 5,000 MW figure from FlexAbility assumes 20% of the EV fleet is V2G-compatible by 2030 and available for dispatch. The actual realizable share in 2030 is much lower due to the regulatory, technical, and commercial barriers described below. (Source - FlexAbility Delrapport 1 (2025))

Nordic energy system context

Nagel et al. (2024) modeled V2G in Norway and Denmark using the Balmorel energy system model for a 2040 system. The central finding — directly relevant to Sweden’s four bidding areas:

V2G value depends fundamentally on the flexibility mix of the system:

Additional results:

• System operational cost reduction: ~3%
• CO₂ emission reduction: ~33% (curtailment reduction + peak fossil displacement)
• V2G supplies up to 55% of system load in DK2 at peak hours under large-scale adoption
• Curtailment reduction in Denmark: ~30%
• Airport V2G revenues: negligible vs home V2G (e.g., DK1: €1.8M airport vs €290.9M home)

Swedish bidding area implication (wiki inference from regional characteristics):

• SE1–SE2 (north, hydro-dominated): likely Norway-like — V2G adds less value; risk of price increases at high adoption
• SE3–SE4 (central/south, VRE-growing + import dependency): more Denmark-like — V2G more valuable; higher adoption economics

Prisoner’s dilemma at scale: large-scale V2G adoption flattens the price duration curve, eliminating the low-price charging valleys that make V2G profitable. Individual incentive to participate remains, but collective charging costs rise. This is a key policy consideration: heavily incentivized mass V2G adoption may erode its own economics. (Source - Nagel et al V2G Nordic Balmorel 2024)

Synergy with transmission: V2G and cross-border transmission capacity are complementary — more interconnection increases V2G utilization and value.

Swedish regulatory grey area

No direct legal barrier exists to discharging an EV battery into the grid. However, several unresolved grey areas create practical obstacles: (Source - Power Circle V2X Synthesis 2024, Source - KTH Thesis V2G Sweden 2024)

Classification ambiguity

An EV connected for V2G can be treated as either:

1. Microproduction facility (mikroproduktionsanläggning) — treating the EV+wallbox combination as equivalent to solar panels or a home battery. This is the approach tested in the PAVE pilot (Göteborg Energi). Implication: changing the vehicle requires updating permits and re-registration, which creates friction for normal vehicle replacement cycles.
2. Mobile injection point — treating the EV as a resource that can inject power at different locations. This would enable cross-location V2G but conflicts with existing requirements for a fixed physical address.

Different network operators have given different answers when asked which classification applies.

Double taxation (dubbelbeskattning)

Electricity charged into an EV battery incurs energiskatt (energy tax) and moms (VAT). If that electricity is subsequently discharged via V2G and sold to another customer, the receiving customer is taxed again on the same kWh.

Skatteverket has introduced a refund mechanism (allowing consumers to reclaim the energy tax on electricity fed back to the grid). However, the refund applies only when discharging to the same concessionary network (koncessionsområde) in which the electricity was originally charged. A consumer who charges in one area and discharges in another (e.g., work in SE3, discharge at home in SE4) loses the refund right. This constrains cross-area V2G and is a specific barrier for mobile use cases. (Source - KTH Thesis V2G Sweden 2024)

Physical address registration

Svenska kraftnät requires a registered physical address for participation in ancillary services markets. DSOs similarly require a known location for local flexibility market participation. EVs are inherently mobile — they cannot easily maintain a single registered location while providing services from multiple physical locations without re-registration at each new site. This limits V2G to a de facto single fixed location per vehicle registration. (Source - KTH Thesis V2G Sweden 2024)

Network code gaps

Swedish nätkoder (network codes) have not been adapted for mobile resources. Connection agreements, measurement, and settlement procedures assume fixed installation points. No standardized procedure exists for a resource that changes location.

Swedish pilots

The Vattenfall/Energy Bank/VW pilot is the most significant current Swedish V2G project — one of the world’s largest at launch. Vattenfall acts as both BRP and BSP, trading aggregated flexibility across the Balancing Market, Nord Pool, and local flexibility markets. VW ID. models with 77 kWh+ batteries are the primary vehicle platform. (Source - Vattenfall Energy Bank VW V2G Pilot 2025-2026)

CheckWatt delivered the first V2G service to a local flexibility market in Sweden in March 2025 — four Volvo Cars EVs delivered 111 kWh to Effekthandel Väst. (Aggregation › CheckWatt — multi-market VPP aggregation at Nordic scale)

V2G as a multi-actor service system

Research increasingly frames V2G not as a technology problem but as a service design challenge — a complex end-to-end service system requiring coordination across users, service providers, and grid actors. A 2026 Chalmers/Polestar/Vattenfall/Göteborg Energi/Svk co-design study (funded by Vinnova, project Implementation of Vehicle-to-Grid Services in Sweden) developed a V2G service blueprint through 18-participant stakeholder workshops, mapping the full service lifecycle across nine phases: (Source - Malakhatka et al V2G Service Blueprint Sweden (2026))

The pre-qualification dead zone

The single most significant service delivery friction identified by the study: hardware commissioning (Phase 5) takes 3–6 months; the subsequent Test Pre-qualification process (Phase 6), in which the Aggregator and BSP verify the EV/EVSE meets Svenska kraftnät‘s technical requirements for FCR/aFRR participation, adds a further 1–5 months. Early adopters bear full capital expenditure (bidirectional wallbox) with no revenue during this window. Proposed remedy: digital twins of local grid segments enabling “one-click” pre-qualification at the contracting stage.

Service design challenges

• Contractual complexity: V2G agreements involve Aggregator, Energy Supplier, BSP, and installer obligations across multiple documents. Workshop participants consistently identified simplicity and transparency as prerequisites for user adoption.
• Divergent value propositions: users primarily want financial clarity and battery state-of-health (SOH) monitoring; abstract grid benefits (CO₂, system stability) are far less persuasive. V2G interfaces must lead with financial projections and battery health — not grid contribution metrics.
• Fuse overload risk: Aggregator backstage signals that fail to synchronize with local building loads can cause V2G discharge to exceed the household main fuse capacity, triggering local outages. This “Incorrect Load Balancing” risk requires local fail-safe mechanisms or smart inverters with autonomous load shedding — distinct from the LV network stress at high fleet penetration documented by FlexAbility.
• Trust as infrastructure: 18% of potential users cite data privacy and cybersecurity as barriers. Immediate visual or haptic micro-feedback confirming that backstage commands have been received is essential to counter the “black box” perception of automated V2G services.
• Pause vs termination: binary service termination triggers full TSO/aggregator deregistration. A “Pause” or “Vacation Mode” — maintaining asset registration during inactivity — preserves historical battery health data and eliminates re-onboarding friction, improving long-term fleet retention.

Barriers

Regulatory and policy

• Absent regulatory framework for V2G — no clear rules; cautious business response
• Double taxation for cross-area V2G discharge
• Physical address registration requirement (Svk, DSOs)
• Classification ambiguity (EV as microproduction vs mobile injection point)
• Nätkoder not adapted for mobile resources
• No EV-specific incentive scheme equivalent to solcellsstöd (solar subsidy) or hembatteriavdrag (home battery deduction)
• Politicians’ knowledge of V2G is low; general interest has not translated into legislative action

Technical

• Software restriction: many vehicles technically V2G-ready but OEM-locked
• AC bidirectional communication protocols incomplete (no SOC data in AC standard)
• Grid code compatibility across regions/countries uncertain
• Battery degradation impact uncertain — contrasting research findings
• LV network stress: FlexAbility Monte Carlo simulations show that V2G + PV penetration begins causing substation overloads at 30–80% penetration depending on network (see below)

Economic

• Weak consumer revenue case: 7–14 SEK/year per vehicle in Swedish simulations vs 378 EUR/year in European optimized pool scenarios
• Bidirectional wallboxes ~2× cost of unidirectional
• Battery warranty risk borne by OEMs — caps on V2G cycling energy (VW imposes limits)
• Business model vacuum: revenue split between OEM, aggregator, energy company, grid operator undefined

Social

• Installed base problem (Sweden-specific): many Swedish consumers already own non-V2G-compatible wallboxes (7,000–30,000 SEK); upgrade cost is a barrier unique to high-EV-adoption markets
• Behavioral change required: consumers must plug in consistently and maintain charge availability
• Systems must be “plug & play” — complexity prevents mass adoption

LV network impacts

FlexAbility (2025) used Monte Carlo simulation (Plexigrid platform) to study how increasing V2G penetration combined with rooftop solar affects residential LV networks during FCR-D upregulation service (~58 activation hours/year). Two Swedish networks studied:

All binding constraints occurred on weekends in Q3 (low residential load + high solar + V2G activation). The 2.7× range in thresholds between two Swedish networks underlines that V2G grid impact is highly network-specific — national averages are unreliable. V2G without smart charging coordination risks destabilizing LV grids while stabilizing the transmission network. (Source - FlexAbility Delrapport 3 (2025))

Ecosystem actors

The Swedish V2G ecosystem requires unprecedented cross-sector collaboration: (Source - KTH Thesis V2G Sweden 2024)

OEM fleet aggregation opportunity: if an OEM aggregates its entire sold EV fleet into a BSP portfolio, it could potentially exceed Svenska kraftnät‘s 100 MW threshold for ancillary service participation — making a vehicle manufacturer a major flexibility market actor. This is described as a first-mover strategic opportunity in the KTH thesis. (Source - KTH Thesis V2G Sweden 2024)

Relationship to other wiki topics

• Demand Response — V2G is a major future DR resource; aggregated EV charging and discharging is a key category
• Aggregation — V2G assets require aggregation to reach market thresholds; CheckWatt delivered first V2G in Swedish LFM; BSP/BRP structure critical
• Energy Storage — V2G is mobile distributed battery storage; complementary to stationary BESS; 5,000 MW potential by 2030 per FlexAbility
• Balancing Markets — V2G can participate in FCR, aFRR, mFRR once regulatory barriers resolved
• Flexibility Market — EVs are a natural DSO local flex resource (large loads, predominantly daytime-parked)
• Svenska kraftnät — physical address requirement and 100 MW BSP threshold are the key Svk-level barriers
• Villkorade Avtal — flexible connection agreements could accommodate V2G charging; relevant to DSO connection design
• Generator Connection Requirements — ACER Rec 03-2023 (NC RfG 2.0 / NC DC 2.0) explicitly brings V2G into scope of EU connection requirements for the first time
• V2G Grid Risks — DSO and TSO Hazards from Bidirectional EV Charging — synthesis of the five DSO/TSO risk categories: LV overvoltage/thermal overload, unintentional islanding, protection-relay degradation, coordinated fleet cybersecurity, and cold-load pickup

Data gaps

• Harmonic distortion and power quality impacts from bidirectional V2G inverter operation on LV networks — no Swedish study covers this quantitatively; relevant to DSO grid code compliance for consumer-grade chargers
• Current status of PAVE, V2X-MAS, PEPP, SCALE pilots — published findings
• Skatteverket position on energy tax refund for V2G: is a cross-area solution being considered?
• Ei position on EV classification (microproduction vs mobile injection) — official guidance or statement
• Svk position on physical address requirement for mobile V2G resources — any planned reform
• Results from Vattenfall/Energy Bank/VW pilot (due 2028)
• OEM commercial V2G launch timelines for Swedish market (Volvo, Polestar) — Polestar confirmed as active Vinnova project partner (2023-00785) working on V2G service design as of May 2026, but no commercial launch date stated
• Pre-qualification timeline data from live Swedish V2G pilots — the 1–5 month TSO pre-qualification delay identified in service blueprint co-design; quantification from actual deployments would confirm or refine this estimate
• Battery degradation empirical data from Swedish V2G pilots