Bidirectional Charging (V2H / V2G)

The EV battery serves as a feed-back-capable store for the building or the grid — dramatically higher self-consumption and dynamic tariff arbitrage.

How does bidirectional charging work?

With bidirectional charging, an electric car's battery can not only be charged but also discharged. In V2H (Vehicle-to-Home), the vehicle battery supplies the building; in V2G (Vehicle-to-Grid), it feeds back into the public grid and can offer balancing services. A typical 60 kWh vehicle battery is equivalent to around six stationary home batteries. During the day, the battery is charged with PV surplus; in the evening and at night, it covers the building's consumption. Technically, this requires a bidirectionally capable vehicle (CHAdeMO or CCS to ISO 15118-20) and a bidirectional wallbox with an integrated inverter that converts the battery's direct current into grid-compliant alternating current. The round-trip efficiency, the ratio of energy withdrawn to energy stored, is around 85 %. An energy manager controls charging and discharging according to PV generation, consumption and driving needs.

Which buildings benefit from V2H or V2G?

The prerequisites are a bidirectionally capable electric car, a bidirectional wallbox, a PV system and a vehicle dwell time of more than 16 hours per day. If the car is constantly on the road, the benefit disappears. Typical properties are detached houses with home offices, multi-family buildings with underground car parks and company car parks where vehicles are parked for long periods. In Austria, V2H for self-consumption is possible without special approval; for V2G, uniform grid rules and remuneration models are still lacking, so grid feed-in is likely to become broadly available only in the coming years.

What does bidirectional charging actually deliver?

The self-consumption rate of the PV system rises from around 30 to 65 to 90 %. A detached house with 10 kWp PV and 10,500 kWh/a yield consumes around 4,500 kWh/a more on site with V2H, equivalent to roughly €800/a and around 700 kg CO2/a. With V2G, remuneration of around €0.15/kWh for energy fed back is added, 500 kWh/a in the standard case. A bidirectional wallbox costs €4,500 to €9,000 (as of 2026, with prices falling), including the special registration with the grid operator. Payback is 8 to 14 years; it improves significantly if a stationary home battery is thereby avoided.

Energy carrier

Strom Netzbezug Hochtarif → Strom Eigenerzeugung mit Auto-Speicher

Savings potential

Eigenverbrauch von 35 % auf 75-90 %

Worked example

A detached house with a home office operates a 10 kWp PV system generating 10,500 kWh/a. Without storage, only 30 % of this is consumed on site (ε = 0.30); the rest flows into the grid at the feed-in tariff. Instead of a stationary battery, a bidirectional wallbox is installed; the electric car with a 60 kWh battery sits in the garage most of the day and serves as storage (V2H). This raises the self-consumption rate to 80 % (ε = 0.80). Taking the round-trip efficiency of 0.85 into account, the additional self-consumption is 10,500 × (0.80 − 0.30) × 0.85 = 4,463 kWh/a. Around 4,500 kWh/a is therefore used additionally in the house instead of being exported, corresponding to a value of roughly €800/a and avoiding around 700 kg CO2/a, because grid purchases are replaced by solar electricity.

Investment & payback

Bidi-Wallbox: 4.500-9.000 € (Stand 2026, fallend); inkl. spezielle Anmeldung · Service life: 10 a · Payback: 8-14 (durch Wegfall Heim-Speicher attraktiver) a

Applicability

Requirements

Exclusion criteria

Typical buildings

Frequently asked questions

What is the difference between V2H and V2G?

V2H (Vehicle-to-Home) uses the car battery as storage for your own building: during the day it charges with PV surplus, in the evening it supplies the house. V2G (Vehicle-to-Grid) additionally feeds back into the public grid and can provide balancing services or spot market arbitrage. V2H is already possible in Austria for self-consumption; V2G still requires uniform grid rules and remuneration models.

Which electric cars can charge bidirectionally?

Bidirectional charging requires a vehicle with a CHAdeMO connector or CCS to ISO 15118-20 with the discharge function enabled. The number of suitable models has been growing significantly since 2025, although manufacturers enable the function partly via software and partly only for specific wallboxes. Before purchasing, check whether vehicle, wallbox and energy manager are actually certified together.

How much does a bidirectional wallbox cost?

As of 2026, a bidirectional wallbox costs between €4,500 and €9,000, including the required registration with the grid operator. Prices are falling as adoption grows. Since the built-in inverter takes over the function of a stationary battery, that purchase is no longer needed, which noticeably shortens the payback of 8 to 14 years.

Is V2H worth it if the car commutes daily?

V2H is worthwhile above all when the vehicle is parked at the building for more than 16 hours a day, for example with home working or as a second car. It must be plugged in during the day to absorb PV surplus and in the evening to supply the house. For a car that is out all day on weekdays, charging falls into the evening and night hours, so the PV benefit is largely lost.

Is bidirectional charging permitted in Austria?

V2H for self-consumption is generally possible in Austria; registration of the installation with the grid operator is required, as with any storage system. For V2G with grid feed-in, uniform technical connection rules and a remuneration model are still lacking. The relevant standards are ISO 15118-20 for communication, IEC 61851-23 for DC charging and the grid operator's connection conditions.

Related measures

Standards & sources

Metering points in the EDM Toolbox

V2G-Wallboxen liefern bidirektionale Energiemengen via OCPP 2.0.1. EDM Toolbox kann Laden/Entladen, SoC, Verfügbarkeit + finanzielle Auswertung (Spot-Tarif) zusammenführen.

All measures