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How do the G99 fast-track (Small Generation Installation) procedures work for domestic solar and batteries?

Short answer

G99 Issue 2 has three fast-track routes. SGI-1: units up to 32 A, limited to 16 A total, install then notify. SGI-2: aggregate under 32 A, export limited to 16 A, DNO replies within 10 working days. SGI-3: aggregate under 60 A, export limited to 32 A, DNO says within 10 working days if studies are needed.

Last checked 24 September 2026 · 1 source

In more detail

  • SGI-2/3: apply on Form A1-2; planned commissioning 10 working days to 3 months after application; confirm commissioning within 28 days on Form A3-2.
  • No install or commissioning before the DNO assessment outcome; if studies needed, follow the standard application (possible chargeable reinforcement).
  • All units must be G98/G99 fully type-tested inverters.
  • Outside SGI: standard application form, studies, quote, possible witness testing.
  • 'Fast-track for <=50 kW' is a misconception - SGI limits are current-based; 50 kW is MCS scope.

The facts, dated

  1. 01
    SGI-2 DNO assessment response time — 10 working days

    standard · GB · checked 24 September 2026 · dcode.org.uk

  2. 02
    SGI-3 aggregate registered capacity limit — 60 A per phase

    standard · GB · checked 24 September 2026 · dcode.org.uk

  3. 03
    Earliest planned commissioning date after SGI application — 10 working days

    standard · GB · checked 24 September 2026 · dcode.org.uk

What we saw in the field

[QA review 2026-09-24] C1-4 and I-7 AGREE. | Earlier notes: Customer 1 wanted 7.5 kW export but the DNO capped it at 5 kW due to local solar saturation - consistent with G99/G100 export-limited offers; installer view that saturated areas get restrictions agrees.

Sources

Last checked: 24 September 2026