Australia is moving rapidly towards Vehicle-to-Grid (V2G) technologies and services, allowing electric vehicles (EVs) to export power back into homes or the electricity grid. Consumer interest is growing, new products are entering the market, and industry attention is focusing.
But while enthusiasm for V2G is increasing, the standards and approval pathways underpinning safe and interoperable deployment in Australia remain immature.
In some cases, V2G functionality is being achieved through non-standard or non-homologated approaches that sit outside the operating conditions originally validated by vehicle manufacturers.
That does not automatically make these systems unsafe, but raises important questions about interoperability, fault management, warranty conditions, and consumer risk as V2G evolves from pilots toward broader commercial deployment.
The key issue isn’t whether reverse power flow is inherently dangerous – it’s whether the EV, charging station, and control system are operating within conditions the manufacturer has tested, validated, and approved for that market.
The basics
The Combined Charging System (CCS) is the dominant EV charging system used in Australia. It covers the connector, pins, communication protocols, testing, and the broader set of standards for the interface between EVs and charging infrastructure.
Within the set of CCS standards, there are two important high-level (‘lots of data’) communications protocols between EVs and charging stations:
- ISO 15118-2 is the first-generation communications protocol, and ISO 15118-20 is the second-generation protocol that formally adds support for interoperable bidirectional power transfer (BPT) enabling standardised V2G functionality. It also improves cybersecurity among broader, additional functionality.
ISO 15118-20 is already being deployed internationally, particularly in Europe, but lags in Australia – in part as some of the structural enablers needed to run it at scale aren’t yet in place here.
Homologation is the formal approval of a specific product configuration and operating mode for a specific market. Homologation confirms that a system has been tested and validated against applicable standards and operating conditions.
Australia has one of the strongest potential consumer cases for V2G globally due to high rooftop solar penetration, significant merchant energy opportunities, and growing demand for flexible energy resources.
V2G is expected to play an important role in Australia’s future energy system, and significant progress is already occurring across standards development, certification pathways, and commercial deployment. The challenge is ensuring deployment scales through interoperable and validated pathways rather than fragmented market-specific implementations.
What could (hypothetically) happen
Interest in V2G is growing, and so is scrutiny of its safety. One concern: could unsupported V2G operation cause an electrical fault – such as an arc flash?
A core principle of systems safety is that serious risks aren’t typically managed by communications software alone, but depend on hardware and software working together – interlocks, properly sequenced contactors (the heavy-duty switches that carry the current), and fault-management systems. Charging and discharging involve serious currents, so the engineering is generally robust.
It may be difficult to conceive how a manipulated ISO 15118-2 message – a protocol vehicles and charging stations use to talk to each other – could by itself cause an arc flash. An arc flash is what happens when an electric arc releases an explosive burst of light and heat, usually because a circuit is broken while current is still flowing.
Whether one occurs depends on physical interlocks and the broader safety architecture, not on any single message (see IEC 61851-23 and ISO 26262). Arcs also aren’t direction-sensitive: they can occur during charging or discharging if something goes wrong.
Modern EV charging systems are designed to ramp current down to near zero before DC contactors open to prevent switching under load. Several layers of hardware and software safety sit behind this.
So the real question isn’t whether one protocol message is dangerous – it’s whether the whole system is operating inside conditions that have been engineered, tested, and approved.
That distinction matters. Forcing a charging system or powertrain into a reverse-power state it wasn’t certified for moves parts of the system outside their tested protection and fault-response limits. Once that happens, the system’s behaviour is unmapped and untested – and that’s when failure modes start opening up.
That can create conditions where:
- Protection devices, switches, and fault-response logic may not behave as designed. They’re all engineered for specific operating conditions. Outside those, there’s no guarantee they’ll interrupt current or respond to faults correctly.
- Contactors may wear out faster. EV power electronics normally ramp current down to near zero before the main DC contactors open, so the switches aren’t carrying load at the moment of disconnect. A reverse-power state the system wasn’t certified for could bypass that sequencing, forcing contactors to open under load and degrading them over time.
- Failure modes become harder to predict or control. If a fault occurs while switching gear is operating outside its tested envelope, the resulting behaviour may not be well-controlled.
Several failures would typically need to align for severe outcomes, and the specific architecture and engineering of a given EV and charging system heavily shape total risk.
Standards matter because systems matter
ISO 15118-20 explicitly covers V2G as part of the charging system’s overall control and safety design, which is core to enabling V2G across industry.
OEM-authorised ISO 15118-2-based V2G implementations should deliver equivalent safety when paired with a manufacturer’s approved charging station(s); these scenarios shouldn’t be characterised as unsafe. What they aren’t is interoperable: a vehicle that supports V2G only via its OEM’s bespoke 15118-2-based setup will work with the approved charging station(s) and little else. Consumers should understand this before committing, because it’s a meaningful form of lock-in.
Beyond these scenarios, safety concerns lie in attempts to induce reverse power flow outside validated configurations, whether through bespoke approaches or manipulated messaging.
That’s where a system can end up operating in conditions no one engineered for, and this is why interoperability and certification matter.
Compliance has to be complete across the system, too: a charging station being approved in one role – e.g., as a grid inverter, say – doesn’t establish that a particular EV and charging station can safely deliver V2G together.
None of this is a criticism of automotive OEMs – they typically operate under rigorous engineering, testing, and safety validation for products in defined operating conditions and use cases. It’s unreasonable to expect every vehicle to safely handle every configuration beyond what it was designed for.
A practical checklist for consumers
It’s fast times in EV engineering – and V2G is very much the future – but you’ll want more than a ‘maybe’. Before treating an EV like an extended home battery, owners should seek written confirmation from their EV manufacturer covering:
- EV makes and models authorised for V2G,
- Charging station makes and models authorised for V2G,
- Any relevant charge limits (e.g., maximum power, V2G energy throughput over time),
- Market or jurisdiction-specific conditions (e.g., which jurisdictions this support applies in, and any applicable segment discriminators, VIN ranges, etc.),
- Minimum technical conditions (e.g., supported firmware versions for both the EV and charging station(s) and allowable control solutions),
- Any key operational exclusions or limitations, and
- Effects on warranty condition(s).
Homeowners may also want to check the implications with their insurer.
Bridging the interoperability gap
Commercial considerations will shape how fast V2G rolls out, but safety validation and system assurance remain non-negotiable at scale. That’s why formal interoperability standards and certification pathways matter: they give EVs, charging infrastructure, and grid systems a scalable, independently verifiable basis for working together safely and predictably.
Some EV and charger combinations have already been engineered to work together outside fully standards-based pathways. Even where those integrations function reliably in a particular setup, approval in one scenario or market shouldn’t be assumed to carry over to another.
Vehicle operating conditions, grid requirements, certification pathways, and regulatory expectations may differ across jurisdictions.
From bespoke integrations to mature deployment
To be clear, a lack of standards-driven, homologated interoperability does not automatically mean a specific V2G deployment is unsafe. Some Australians are already reporting successful outcomes despite the aforementioned risks.
Importantly, pilot and early deployment environments are precisely where industry learns through these issues — helping identify interoperability gaps, validate operating conditions, improve standards implementation, and inform future certification and market pathways.
But scalable deployment beyond pilot environments requires more than successful bespoke integrations. It requires interoperable standards, clear homologation pathways, coordinated testing, and confidence across the broader EV charging ecosystem.
Australia has a genuine opportunity to become a leading V2G market, in which the transition from bespoke integrations to trusted standards-based deployment is now the critical next step.
In the meantime, consumers considering V2G should seek confirmation from their vehicle manufacturer regarding compatible charging equipment, approved operating conditions, and any relevant warranty of technical requirements.
Riccardo Pagliarella and Peter Kilby are Domain Experts for the Vehicle-Grid Network (VGN). For those seeking more technical information, please go to Riccardo’s original LinkedIn article.
The views expressed in this article are those of the individual authors and contributors and do not necessarily represent the views of the Vehicle-Grid Network, its partners, participants, funding bodies or working groups.
