G99 approval is required for vehicle-to-grid (V2G) — but not for vehicle-to-home (V2H). That distinction matters more than almost anything else in this guide. If you are planning to use your EV’s battery to power your house without sending electricity back to the public network, you generally do not need a G99 application at all. If you want to export energy to the grid and participate in a V2G tariff like Octopus Power Pack, G99 is a legal requirement and typically takes 10 to 65 working days depending on your region and application type.
G99 — formally Engineering Recommendation G99 — is the Energy Networks Association’s standard for connecting generation or storage equipment to the local distribution network. It replaced the older G83 and G59 standards and covers all residential and small commercial installations that export electricity to the grid. Your Distribution Network Operator uses it to assess whether your local network can safely handle power flowing back from your car.
Key Takeaways
- G99 approval is required for V2G (grid export) — not for V2H (home-only use)
- Any V2G export exceeding 3.68kW triggers the full G99 requirement, which applies to most bidirectional chargers
- The application requires a Single Line Diagram, charger datasheets, protection specs, and site details
- Timescales range from seconds (UKPN auto-approval) to 65+ working days for standard G99
- If G99 is refused, you can still use your bidirectional charger for V2H — no export, no approval needed
Does your installation need G99?
Start here before doing anything else. The answer determines whether you need to engage with your DNO at all.
| Installation type | Exports to grid? | G99 needed? | Alternative |
|---|---|---|---|
| V2H only (home use, no export) | No | Generally no | — |
| V2G export, ≤3.68kW | Yes | G98 notification (simpler) | Notify DNO |
| V2G export, >3.68kW | Yes | Full G99 required | Engineering assessment |
Most bidirectional EV chargers operate well above the 3.68kW threshold. The NexBlue Point 2 operates at 7.4kW. The Zaptec Go 2 operates at 7.4kW to 22kW. The Wallbox Quasar 2 operates at 11.5kW. All of these exceed the G98 threshold, which means a full G99 application applies for any V2G use.
G98 is the simpler notification route that applies to lower-power installations. It does not require a formal engineering assessment — it is closer to an administrative notification than an approval process. If your system genuinely operates below 3.68kW for export, confirm with your installer whether G98 applies.
G100 is a separate regime — not an application type but an outcome. If your DNO determines that your local network cannot support export, they may approve your connection subject to a G100 export limitation that caps how much power you can send to the grid.
For a broader overview of the DNO process, see our guide to DNO approval for EV chargers.
What is G99?
G99 — Engineering Recommendation G99 — is the technical standard published by the Energy Networks Association that governs how generation and storage equipment connects to the UK’s low-voltage and high-voltage distribution networks.
Before G99, the equivalent standards were G59 (for installations above 16A per phase) and G83 (for smaller installations). G99 consolidated and updated these into a single framework that covers modern technologies including battery storage and, progressively, bidirectional EV chargers.
For your V2G installation, G99 is the mechanism your DNO uses to confirm three things: that your bidirectional charger meets the required protection and safety specifications; that the equipment will not cause voltage or frequency problems on the local network; and that the local network has sufficient capacity to absorb your export.
Approval under G99 is a legal prerequisite. No V2G connection can be energised — meaning switched on and used for export — before the DNO has issued approval.
The G99 application process — step by step
Your installer should lead on this, but understanding the process yourself prevents delays.
Step 1: Confirm that G99 applies. If your V2G export exceeds 3.68kW — which it almost certainly will — confirm with your installer that G99 is required. Establish early whether V2H or V2G is your goal, because V2H does not require this process.
Step 2: Pre-application feasibility check. Most DNOs offer a free pre-application check through their online connections portal or connections team. Submit your site location and a brief description of the proposed installation. This gives an early indication of whether your local network has capacity, before you spend money on hardware or application fees.
Step 3: Submit the formal G99 application. The application is submitted via your DNO’s online portal using the standard ENA application form. The minimum documentation required is:
- A Single Line Diagram (SLD) of the proposed installation — an electrical schematic showing how the charger connects to your consumer unit and the grid connection point
- Datasheets for your bidirectional charger including protection specifications (anti-islanding, voltage and frequency limits)
- Site location details and metering arrangements
- A letter of authority signed by the landowner
Your installer should also complete the ENA’s standard EV installation form alongside the G99 application — this is a supplementary form specifically for vehicle charger connections.
Step 4: DNO assessment. Your DNO reviews the application and assesses the technical and network capacity implications. They then issue a connection offer: a formal document setting out the terms, any conditions or limitations (such as G100 export caps), and the associated costs.
Step 5: Acceptance and commissioning. Accept the offer, complete the physical installation, submit the final commissioning notification to the DNO, and receive the Final Operational Notification. Your V2G connection is then legally active.
How long does G99 approval take?
This is where regional differences matter significantly.
| Application route | Target timescale | Real-world range |
|---|---|---|
| UKPN automatic (ENA type-tested charger) | Seconds | Immediate for 80% of applications |
| Fast-track G99 | 10 working days | 1 day (Northern Powergrid best case) to 4 weeks |
| Standard G99 | 45–65 working days | 6 weeks to 6+ months in constrained areas |
Figures vary — verify current timescales directly with your DNO before planning an installation schedule.
UK Power Networks (South East, East Anglia, London): As of 2026, UKPN automatically approves approximately 80% of V2G applications within seconds for ENA type-tested chargers. The remaining 20% follow the standard G99 route. If your charger holds ENA type-testing and you are in the UKPN area, this is the fastest route to a live V2G connection in the UK.
Northern Powergrid (North East, Yorkshire): Fast-track G99 can complete in a single working day for straightforward, low-impact connections. Standard applications take around 45 working days.
National Grid, SP Energy Networks, SSEN, Electricity North West: Standard G99 applies — allow 45 to 65 working days as a planning assumption. Rural areas in these regions are more likely to experience longer timescales due to constrained network assessments.
One important process note: incomplete applications reset the clock. If your DNO requests additional information and you take time to provide it, the assessment period does not pause — it may restart from when they receive the complete submission. Have all documents ready before submitting.
Costs associated with a G99 application
Residential V2G applications at the domestic scale are at the lower end of the G99 cost spectrum. Unlike commercial solar or large storage installations, a domestic bidirectional EV charger typically does not trigger large DNO assessment fees.
That said:
- Assessment fees vary by DNO — some residential low-carbon technology applications attract a nominal fee; others do not
- Fees are non-refundable even if you decline the connection offer after receiving it
- Physical connection costs at the residential scale are usually negligible — your charger connects to your existing meter and consumer unit
- Ask your installer explicitly whether the G99 application is included in their quoted price, and who pays any DNO fees
What if G99 is refused?
Refusal is not the end of the road. If your DNO determines that your local network cannot accommodate your V2G export, you have four options:
-
Accept G100 export limitation. Install the bidirectional charger with a capped export level set by the DNO — possibly 0kW during peak periods, or a reduced rate at other times. Your V2H capability is completely unaffected; only the grid export is limited.
-
Apply for a flexible connection. Accept curtailment during periods of grid stress, in exchange for permission to export at other times. Less predictable than a firm connection, but may be the only option in constrained areas.
-
Fund grid reinforcement. Ask the DNO what it would cost to upgrade the local network to accommodate your export. At domestic scale this is rarely practical — reinforcement costs can reach six figures.
-
Switch to V2H only. Abandon V2G and use the bidirectional charger purely to power your home. No export, no G99 needed, no DNO involvement. You lose the V2G income opportunity but retain all the V2H resilience benefits.
For most households, option 4 is the most practical fallback if V2G export is refused. The bidirectional charger hardware works for V2H regardless of the DNO’s decision on V2G.
Before committing to V2G hardware, check which vehicles support bidirectional charging — see our guide to V2H-compatible cars.
Frequently Asked Questions
Do I need G99 approval for a V2H charger?
Only if you plan to export energy to the grid (V2G). V2H systems that power your home without sending electricity to the public network generally do not need G99 approval. Since most bidirectional EV chargers operate above the 3.68kW threshold, any V2G use will require a full G99 application to your Distribution Network Operator.
How long does a G99 application take for a V2G charger?
Timescales vary significantly by DNO and application complexity. UK Power Networks automatically approves around 80% of V2G applications in seconds for ENA type-tested chargers. Northern Powergrid can fast-track straightforward applications in a single working day. Standard G99 applications typically take 45 to 65 working days. Budget at least 12 weeks to be safe when planning your installation timeline. Figures vary — verify current data directly with your DNO.
What documents do I need for a G99 application for a V2G charger?
You need a Single Line Diagram of the proposed installation, datasheets for your bidirectional charger including protection specifications, site location and metering details, and a letter of authority signed by the landowner. Your installer should also complete the ENA’s standard EV installation form alongside the G99 application form. Incomplete applications extend the process, so have everything prepared before submitting.