We faced a formidable task: proving a groundbreaking V2G system could meet the UK’s export approval standards with no roadmap.
We used our industry expertise and innovation partnerships to lead the full technical process: from designing the test plan to running the lab setup and successful testing.
Our results and report enabled Octopus to secure full G99 certification and launch a revolutionary V2G system that strengthens the grid, supports renewable energy and sets the direction for future innovation.
Octopus Energy is a global energy company that uses technology to make energy fairer, greener and simpler. Their approach combines renewable power, smart tariffs and the Kraken software platform to help customers use cleaner energy at the best times. Since launching in 2015, they’ve become well known for driving innovation in the energy market.
One of their major innovations is Power Pack, Octopus’s first Vehicle-to-Grid (V2G) tariff. Power Pack allows customers to charge their electric vehicle (EV) when energy is greenest and export electricity back to the grid when it’s needed most. Customers share in the benefit through guaranteed free charging of their EV.
To make this bold idea work reliably and at scale, Octopus partnered with BYD and Zaptec to create a bundle: a BYD Dolphin EV with V2G capability, a Zaptec Pro bi-directional charger alongside a tariff that gives customers free home EV charging. This package not only helps drivers cut running costs and lower their carbon footprint, but also supports a more flexible, stable UK energy system.
To make this visionary solution a reality, Octopus partnered with Resillion to lead the way in standards compliance testing.
This was a genuine leap forward – with no precedent anywhere in the UK energy sector.
For an EV to send power back to the grid, it must pass the UK’s G99 standard, which checks things like voltage control and how the system behaves during faults. This is especially difficult for “AC” V2G, where the onboard charger of the car is used to convert the direct current energy in the battery to the alternating current of the grid. Some of the requirements are satisfied by the car, and some by the charger, so that the whole system must work seamlessly together in a way that meets the requirements.
Distributed Energy Resources (DERs), such as EV chargers, bridge physical infrastructure and the digital world. While this connectivity unlocks new capabilities, it also introduces a broader cyber attack surface that can be exploited. Vulnerabilities in firmware and insecure APIs can expose these devices to threats such as remote code execution and data interception. At scale, a coordinated attack on DERs could resemble a distributed denial-of-service (DDoS) event, overwhelming grid infrastructure and disrupting operations. Cyber security is therefore a critical aspect of the certification process.
As the Power Pack Bundle was the first of its kind – outside of innovation hardware – to achieve G99 certification, we collaborated closely with industry experts to redefine existing methodologies, tailoring them to the specific demands of AC V2G.
The project needed multiple components to work perfectly together:
Resillion supported the development of a G99 compliance evidence base for the ENA through rigorous technical testing and cyber security assessments across the entire bundle.
We worked alongside Octopus throughout the entire G99 journey, from the first conversations about requirements to the moment all tests were finally signed off. The work was hands-on, iterative and often problem-solving in real time. Turning experimental ambition into certified reality.
We started by digging into the full G99 rulebook and reviewing BYD’s early evidence to understand exactly where the risks were. From there, we built a practical, end-to-end test plan that PNDC and BYD could follow in the lab. This included clear sequences, expected behaviours and how every piece of data would be captured.
Next, we brought the whole system together at PNDC: the EV, the bi-directional charger, the grid-interface relay and the control software. With the setup in place, we ran early ‘shakedown’ sessions to uncover issues before official testing. These sessions helped BYD refine and update their firmware so we could enter G99 testing with the strongest possible starting point.
Once everything was ready, we moved into full G99 testing. We oversaw each of the 14 mandatory tests, ensuring the setup, data and evidence were rock solid.
The G99 standard includes some security references and standards which need to be addressed as part of the certification, however, these were not specific to this new solution, and did not directly map, leaving some risk gaps. In close collaboration with industry experts, we completed a full analysis of the security requirements of the standard to define and justify which framework and security reference we would use in the assessment. We then completed detailed mapping of all the connection points, communication methods and protocols in the solution for complete threat modelling.
We then audited the testing completed by BYD and performed a gap analysis, feeding back where we felt the testing was insufficient so that the remaining risks could be addressed. We also submitted a recommendation for hardening of the cyber security requirements in the G99 standard to the standards body to better secure the national infrastructure in the future from these developments.
With testing complete, we pulled everything together. A full evidence pack, support for the ENA Type Test Register submission and a controlled decommissioning of the lab setup. Octopus Energy, BYD and Zaptec left the process with a fully evidenced and fully compliant V2G solution ready for the next stage.
By proactively testing under the same conditions that had exposed weaknesses elsewhere, the organisation reduced the likelihood of similar incidents occurring in its own rollout.
By completing all G99 tests and supporting the ENA Type Test Register submission, we helped Octopus deliver a first-of-its-kind, fully certified secure V2G customer offering in the UK. This milestone gives Octopus the confidence to roll out the Power Pack Bundle at scale, knowing the system meets the UK’s strict safety, cyber and grid-connection requirements.
With certification secured, Octopus can now bring forward a V2G solution that genuinely revolutionises how drivers interact with the grid, allowing EVs to charge when energy is greenest and export when the grid needs support.
Instead of relying on fixed prices, the benefit comes from optimised charging and discharging patterns, which access clean energy and the full range of flexibility markets , all managed seamlessly by the Kraken platform.
Interest in the solution has been strong, with thousands of customers registering interest for the Power Pack Bundle and the first customers recently onboarded onto the scheme. For Octopus, this demonstrates both market demand and the strategic importance of offering a system that has been tested, certified and independently validated.
Beyond consumer impact, the wider value to the UK energy system is significant. Each V2G-enabled vehicle acts as a small, distributed energy asset, helping to absorb renewable energy when the grid has surplus and supporting the grid during peak demand. This improves grid flexibility and reduces reliance on traditional fossil-fuel generators. It will contribute directly to a cleaner, more secure and resilient national infrastructure, and lower bills for all customers, not just those that join the scheme.
We chose Resillion because they shared our desire to move quickly and learn by doing”
Resillion’s deep experience in grid compliance and technical standards meant we were well placed to take on the challenge. With no established framework for AC V2G certification, Octopus needed a partner capable of navigating uncharted territory.
Instead of treating compliance and cyber security separately, we tested and evaluated them together across the end-to-end solution. This gave Octopus a single, coherent view of performance, risk and regulatory readiness – providing confidence where no formal standard yet existed.
Resillion’s established partnership with PNDC, the isolated-grid innovation centre at the forefront of electrification research, gave this project a major advantage. Our access to their trusted test environment enabled fast scheduling, efficient test cycles, which reduced time, cost and complexity.
V2G projects are redefining the energy landscape, and Resillion helped pave the way to full G99 compliance. We worked across automotive, charging, cloud and grid stakeholders to solve problems in real time, establishing a new benchmark and proving what’s possible for the rest of the industry.
Providing solutions in a unified, structured approach across all critical domains to enable end-to-end quality.
Providing solutions in a unified, structured approach across all critical domains to enable end-to-end quality – Because we’re the only ones who can.
