# G98 vs G99 — when does V2L trigger DNO notification? > ENA **G98/G99** govern equipment that runs **in parallel** with the public grid. A true islanded V2L feed — physically separated by a changeover so it can **never** run in parallel or export — is generally **outside** G98/G99 and is treated as a load. The moment a system can export or synchronise (true V2G/V2H), it is in scope: G98 is the lighter notify-not-approve route for small type-tested microgenerators within the G98 scope threshold, G99 covers larger or island-capable systems and generally needs DNO acceptance **before** energising. The exact G98/G99 clause locators are **Not confirmed** pending the official PDFs. **Safety frame.** This is education, not an instruction to carry out work. Work connecting V2L equipment to fixed wiring is safety-critical and may be notifiable under Part P. It must be designed, installed, inspected and tested by a competent person to the current edition of BS 7671. Vehicle manufacturers generally do not sanction back-feeding fixed wiring from V2L outlets; follow manufacturer instructions. ## In short - G98/G99 apply to equipment running **in parallel** with the grid; **true islanded V2L** (changeover, no export) is generally outside them, treated as a load. - **G98** = notify-not-approve for small, type-tested microgenerators within the G98 scope threshold, in parallel. - **G99** = larger or island-capable; generally needs DNO **acceptance before energising**. - G99 Issue 2 brings **electricity storage incl. V2G EVs** into scope — new mandatory storage requirements from **1 March 2026**. - Exact G98/G99 clause/section locators are **Not confirmed** (pending the official PDFs); whether a changeover truly prevents parallel operation is a design-and-test matter. **Where this stops:** This explains when the DNO regime applies. Whether a given changeover genuinely prevents parallel operation, and the connection application itself, are competent-person and DNO matters. ## The trigger is parallel operation G98 and G99 govern equipment that operates **in parallel** with — synchronised to — the public network. A pure islanded V2L feed, physically separated by a changeover so there is no possibility of back-feed, is generally **not** a parallel connection. The card's clearest hook: where an EV/charger **cannot** operate as a V2G EV (cannot export or parallel), it is treated as a **load**, outside G99. **Figure: Grid-parallel vs islanded — the DNO-notification line.** Running a source in parallel with the grid engages ENA G98/G99 (DNO notification); a true islanded changeover that never connects the two together is generally treated as a load, outside G98/G99. _Two arrangements. On the left, the grid and the EV/source are connected together (in parallel) — this engages ENA Engineering Recommendations G98/G99, so the DNO must be notified. On the right, a break-before-make changeover switch connects the load to either the grid OR the EV/source, never both together (islanded) — a source that can never run in parallel or export is generally treated as a load and sits outside G98/G99. Whether a given changeover genuinely prevents parallel operation is a design-and-test matter for the competent person and the DNO. The exact G98/G99 clause locators are Not confirmed pending the official PDFs._ ## G98 vs G99 - **G98** — the simplified, notify-not-approve route for small, fully type-tested microgenerators within the G98 scope threshold, in parallel with the LV network. - **G99** — everything larger, not type-tested, or designed to work in island mode; generally a connection application accepted by the DNO **before** energising. - **G100** — export/import limitation schemes that cap net flow, which can keep a system in a lower tier. Not usually relevant to island-only V2L. G99 Issue 2 expressly brings **electricity storage, including V2G EVs**, into scope, with new mandatory storage requirements recorded as in force from **1 March 2026** — relevant when timing any grid-parallel V2H/V2G advice. > **Not confirmed:** The exact G98/G99 Issue 2 clause/section numbers are not yet confirmed against the official ENA PDFs; the citation/edition is checked (public-primary) while the clause substance is pending a licensed/source-text check, so we render precise locators Not confirmed. Whether a given changeover genuinely prevents parallel operation (a momentary parallel transfer can pull it back into scope) is a design-and-test matter for the competent person and the DNO. ### How this is made and proven compliant **What governs it:** ENA EREC G98 / G99 (parallel connection of generation/storage) + G100 (export/import limitation); BS 7671 §551.7 (parallel operation) for the installation side **Who may do it:** A competent person determines whether the arrangement is grid-parallel or genuinely islanded, and makes any G99 connection application; the DNO accepts the connection where required. **How compliance is demonstrated:** Establish whether the system can export/parallel (in scope) or only island via a break-before-make changeover (out of scope); For grid-parallel: a G98 notification or a G99 connection application accepted by the DNO before energising; Prove the changeover genuinely prevents parallel operation (design and test) ## FAQ ### Do I need to tell the DNO about a V2L backup? Generally not, if it is a true island that can never export or run in parallel (separated by a break-before-make changeover) — it is treated as a load. The moment it can export or synchronise (V2G/V2H), G98 or G99 applies and you must notify or apply to the DNO. ### What's the difference between G98 and G99? G98 is a lighter notify-not-approve route for small type-tested microgenerators within the G98 scope threshold. G99 covers larger or island-capable systems and generally needs DNO acceptance before energising. ### Why don't you quote the exact G99 section numbers? The official G98/G99 Issue 2 PDFs are not yet in our reference library, so we treat exact section numbers as inference and render them Not confirmed rather than cite numbers we have not verified. --- _Author: Martin — qualified UK electrician (BEng Mech Eng; vehicle mechanic)._ _Last reviewed: 14 June 2026. Written against: BS 7671:2018 + A4:2026._ _Status: published. General information, not project-specific design advice._ _[How we source this](/methodology) — evidence hierarchy, confidence flags and source policy._ ## Sources 1. ENA — connecting generation/storage to the networks — https://www.energynetworks.org/industry/connecting-to-the-networks/connecting-generation-to-the-electricity-networks (exact G98/G99 locators Not confirmed pending the official PDFs) 2. ENA G98/G99 forms — https://www.energynetworks.org/publications/all-g98-g99-forms