G99 is the UK distribution-code route for connecting power-generating modules (generation and many storage systems) to the distribution network. It sets the technical requirements and the DNO connection/commissioning process for generation equipment.
In EV charging terms:
- A normal EV charger is a load, so G99 is not usually the charger compliance route.
- G99 becomes relevant when your project includes generation/export capability, e.g.:
- V2G / bidirectional charging (EVSE + vehicles exporting)
- On-site PV/BESS that can export to the grid
- Any “regenerative” / exporting equipment connected behind the meter (G99 explicitly addresses “regenerative equipment” in recent issue notes).
G99 also ties strongly to type-tested evidence and DNO application/commissioning steps (e.g., using ENA Type Test Register references can reduce what needs submitting with the application).
G100 (ENA Engineering Recommendation G100)
G100 is about Customer Export and Import Limitation Schemes (often called CLS): controls installed on the customer side that ensure the site doesn’t exceed an agreed export limit (and, in newer framing, import limits too).
In EV charging terms:
- G100 is commonly used when the DNO says: “You may connect, but you must cap export to X kW” (or cap import).
- In mixed sites (PV + BESS + EV charging), G100-style control often sits in the EMS / site controller, measuring at the point of connection and curtailing/export-limiting accordingly.
The practical difference (quick rule)
- G99 = permission + technical requirements to connect generation/exporting equipment.
- G100 = the method to enforce an agreed export/import cap (a limitation scheme).
Many real projects use both: e.g., a site connects PV/BESS under G99, but the DNO only allows export if a G100-compliant CLS is installed and evidenced.
What you typically need to do (high-level checklist)
- Decide if there is export capability (V2G, PV, BESS). If yes → you’re in G99 territory.
- Engage the DNO early and follow their published G99 application route (many DNOs provide step-by-step pages and forms).
- If the DNO imposes an export/import cap, design a Customer Limitation Scheme (CLS) aligned to G100 and document it in the format DNOs expect (G100 appendices/templates are commonly referenced by DNOs).
- Ensure you have the right type-test / evidence trail for the exporting equipment (and any interface protection) and use ENA compliance references where applicable.
- Commissioning & operational notification: G99 projects often require agreed commissioning scope (sometimes witnessed) and proper completion/submission of installation documentation.