G99 is the engineering recommendation governing the connection of generation equipment to distribution networks, requiring DNO approval for systems over 16A per phase.
G99 (formerly G59) is the Engineering Recommendation published by the Energy Networks Association (ENA) that governs how generation equipment connects to UK distribution networks.
G99 application is required for:
Smaller systems fall under G98 (simplified notification).
| Stage | Typical Duration |
|---|---|
| Pre-application response | 10 working days |
| Assessment (simple) | 25 working days |
| Assessment (complex) | 45+ working days |
| Offer validity | 90 days |
We streamline G99 processes through:
G98 is the DNO notification process for small-scale generation systems up to 16A per phase (3.68kW single-phase), allowing 'fit and inform' installation without pre-approval.
Distribution Network Operators own and operate the local electricity distribution networks that deliver power from the national grid to homes and businesses.
Solar photovoltaic systems convert sunlight directly into electricity using semiconductor cells, enabling homes and businesses to generate their own renewable power.
Export limitation restricts how much electricity a solar or battery system can send to the grid, required when local network capacity is constrained.