ENA EREC G99 Issue 2
Grid-code type testing to G99 Issue 2
The British connection standard for generation above the G98 threshold, and the one that names a variable AC test supply in its own text.
Issue 2 introduced requirements for Power Generating Modules incorporating Electricity Storage that came into force on 1 March 2026. Anyone connecting storage in Britain is inside that regime now.
Why this reaches the test bench
G99 Annex A.7.1.2.2 specifies over/under-voltage type verification carried out by operating the module in parallel with a variable AC test supply, with the test voltage applied in steps of 0.5% or less, held longer than the trip delay, then stepped in a single jump to measure trip time. The document also states that a fully integrated package can be tested in a factory environment, for example on a grid simulator. That is a written-down specification for a programmable AC source.
What gets tested
- Interface Protection
- LFSM-O
- LFSM-U
- RoCoF
- Fault Ride Through
- Vector Shift
Northern Ireland
Northern Ireland runs its own variant: NIE Networks publishes ENA EREC G99/NI. Even within the UK the standard forks.
Normatively referenced
BS EN 50549 series · BS EN 50160 · BS 7430 — British and European documents, none of them American.
How this differs from the American regime
The American equivalent regime is IEEE 1547 with UL 1741 SA/SB — different tests, different trip settings, a different certification culture. A US page cannot serve a British connection application.
Sources
- ENA EREC G99 Issue 2 — Energy Networks Association, via the GB Distribution Code site. Retrieved 2026-09-05.Supports: Issue 2, dated 10 March 2025; the storage requirements in force 1 March 2026; Annex A.7.1.2.2 test method