V2H Bidirectional EV Charging — UK Installation Guide

Three acronyms get used interchangeably in marketing copy, but they describe materially different installations with materially different paperwork. Before specifying a charger, the electrician must know which one the client actually wants — the DNO notification, the inverter rating and the BS 7671 treatment all change.

1. V2G — Vehicle-to-Grid. The vehicle exports power into the public distribution network and surplus is sold to the grid via a flexibility platform such as Octopus Power Pack. Always G99 notifiable. Requires a smart export meter and an export limit on the inverter.
2. V2H — Vehicle-to-Home. The vehicle exports power into the dwelling only. No power is sold to the grid; surplus household generation can charge the vehicle. The most common architecture for UK homeowners because the economic case is tariff arbitrage. May sit under G98 with a verifiable export-limit device, but most installations default to G99.
3. V2L — Vehicle-to-Load. The vehicle provides a standalone AC outlet (typically 13 A or 16 A) via an adapter or built-in socket. No charger involved, no DNO interaction, no BS 7671 prosumer treatment. Examples: Kia EV6, Hyundai Ioniq 5, Ford F-150 Lightning.

For the underlying BS 7671 framework that governs all three modes, see our Section 722 EV charging A4:2026 changes guide. For the Chapter 82 prosumer interaction rules that apply to V2H and V2G, see our prosumer A4:2026 guide.

The connector determines whether bidirectional charging works at all. The two DC fast-charge standards on the UK road — CHAdeMO and CCS Combo 2 — have very different bidirectional histories.

ISO 15118 defines how an EV and a charger talk beyond the basic "cable plugged in" pilot signal. ISO 15118-2 (2014) defined Plug & Charge and basic high-level communication. ISO 15118-20 (2022) is the bidirectional extension — the standard that turns the vehicle from a passive load into a managed two-way power source.

For UK installs in 2026, the practical implication is that the charger and vehicle must be a matched pair from a tested compatibility list. Wallbox Quasar 2, Indra V2H, dcbel r16 and EVTec hybrid units publish compatibility matrices — treat these as gospel.

A bidirectional charger converts between the DC inside the vehicle battery and the AC inside the dwelling. Where that conversion happens — inside the charger (DC-coupled) or inside the vehicle (AC-coupled) — drives the inverter rating, the cable size, the BS 7671 treatment and the cost.

1. DC-coupled bidirectional — the charger contains a full bidirectional inverter. The vehicle exports raw DC over the CHAdeMO or CCS pilot; the charger converts to 230 V AC and feeds the consumer unit. Typical rating 7-11 kW for V2H, up to 22 kW for commercial V2G. Examples: Wallbox Quasar 2, Indra V2H, EVTec hybrid.
2. AC-coupled bidirectional — the vehicle's onboard inverter does the conversion. The charger is essentially a smart contactor with metering and ISO 15118-20 comms. Lower charger cost, limited by the vehicle's onboard inverter (typically 7-11 kW). Examples: certain Renault models, Wallbox Pulsar in V2H mode.
3. Split-architecture — a DC charger feeds a separate hybrid solar/battery inverter. Vehicle and home battery share the inverter. Examples: dcbel r16, Sigenergy SigenStor with EV add-on. More complex but one inverter handles solar, home battery and V2H — useful where the customer already has PV.

A bidirectional EV charger's inverter has to do two jobs normally done by two products. In grid-tied mode it synchronises with the public supply. In island mode (grid down) it becomes the voltage and frequency reference for the dwelling — the role of an uninterruptible power supply.

BS 7671:2018+A4:2026 introduced Chapter 82 — Prosumer's Electrical Installations (PEIs) — for dwellings that both consume and produce electricity. A V2H bidirectional EV charger is a prosumer source, and Chapter 82 governs how it integrates with the rest of the installation. Section 722 takes explicit account of this: Reg 722.826.3.201 ties EV charging installations to the prosumer requirements of Chapter 82. Section 712 governs solar PV systems only, so a vehicle acting as a source is treated under Section 722 and Chapter 82, not Section 712. A note in Chapter 57 (Stationary Secondary Batteries) reinforces the point, directing the reader to "Section 722 and Chapter 82" for the supply of a fixed installation by electric vehicles.

For a deeper walk-through of the prosumer rules introduced in A4:2026, see our Section 712 prosumer A4:2026 guide. For the EV-specific Section 722 changes, see our Section 722 EV charging A4:2026 changes.

Engineering Recommendation G99 governs the connection of generation to the UK distribution network. If a V2H installation can export to the grid — even briefly — it falls under G99. The G98 framework covers single-phase installations up to 16 A per phase (3.68 kW) with a "fit and inform" approach; anything larger needs prior DNO approval under G99.

1. G98 Type Tested — micro-generation up to 16 A per phase, with a Type Tested device on the ENA register. Installer connects and notifies the DNO within 28 days. A small V2H unit with verifiable export limit at 3.68 kW per phase can sometimes sit here, but most bidirectional chargers exceed this rating.
2. G99 Fast Track — single Type Tested units up to 11 kW (single-phase) or 17 kW (three-phase) where the network has capacity. Application via the ENA Connect Direct portal; DNO responds within 10 working days. Most domestic V2H installs sit here.
3. G99 Full Application — above Fast Track or where the network can't accommodate without study. Up to 65 working days plus any reinforcement costs. Rare for V2H, common for commercial V2G.
4. Export limitation — a Type Tested export limitation device on the inverter can keep a high-rated unit within a lower G98/G99 threshold. The DNO will require evidence (commissioning print-out, datasheet, photos) that the limit is enforced.

The most compelling V2H pitch is "you keep the lights on when the grid goes down". Delivering this requires a transfer switch, careful earthing design and a clear understanding of which circuits will be supplied during an outage.

The economic case for V2H rests on the spread between cheap overnight electricity (Octopus Intelligent, Octopus Go, EDF GoElectric) and expensive daytime electricity. A vehicle charged at 7-10p/kWh and discharged during the 4-7pm peak at 30-40p/kWh saves the spread, less round-trip efficiency losses (typically 72-81% round-trip).

For the broader smart-tariff context that V2H plugs into, see our smart EV charging guide. For the underlying unidirectional install that precedes any bidirectional upgrade, see EV charger installation.

A bidirectional EV charger is a relatively new beast on a periodic inspection — by 2026 inspectors are starting to encounter them on EICRs. Coding follows prosumer-install logic with EV-specific overlays from Section 722.

Vehicle manufacturers vary on whether V2H/V2G affects the battery warranty. Some explicitly support it (Nissan); others are silent; others exclude V2X from cover.

Part P covers electrical safety in dwellings in England and Wales (Scotland and Northern Ireland have parallel arrangements). A V2H bidirectional charger installation is notifiable — via a Competent Person Scheme (NICEIC, NAPIT, Stroma, ELECSA) or direct notification to local authority Building Control.

For an end-to-end view of the surrounding install — cable sizing, RCD selection, supply upgrade considerations and certification — see cable size for EV charger and V2G installation guide which dives deeper into the grid-export variant of bidirectional charging.