DNO application timescales, network by network: from a G98 notification to a G99 approval

The short answer

There are two clocks, and only one of them makes you wait. If your inverter is rated at 16A per phase or less, which the ENA connection guide puts at 3.68kW single phase and 11.04kW three phase, it falls under G98: your installation team fits it and tells the network operator afterwards, within 28 days at most DNOs. Nothing to wait for. The G98 vs G99 guide covers the split; this one is about the calendar.

Above 16A per phase, or in most cases once a battery is added, you are in G99 territory and the DNO must agree before anything is switched on. Since 9 November 2022 the DNOs have run the revised fast track route for small type tested systems, and the ENA guide says it cuts the DNO answer 'from 45 days to 10 days or less'. Larger systems, island mode batteries and anything outside the fast track limits take the standard route, where the regulated backstop is a quotation within 45 working days.

G98: fit and notify, and what the 28 days actually is

The 28 days is not a waiting period. It is the deadline for your installation team to tell the DNO the system exists. UK Power Networks puts it plainly: if the installer can connect the system, 'all they need to do is simply notify us of the installation within 28 days'. National Grid Electricity Distribution, SSEN and Electricity North West state the same 28 day window. SP Energy Networks asks for the commissioning confirmation within 30 days and 'will not normally object to the connection, subject to compliance with G98'.

The legal root is regulation 22 of the Electricity Safety, Quality and Continuity Regulations 2002: a source not exceeding 16A per phase is exempt from agreeing specific terms with the distributor, provided it disconnects when the grid supply is lost and the installer ensures the distributor is advised 'before, or at the time of, commissioning the source'. Your installation team sends the form. You do not.

G99: what the DNO does with your application

A G99 application asks the DNO to check that the local network can take what you want to connect. On the fast track route, Form A1-2, that check is standardised: every unit a fully type tested inverter, total capacity including storage within 32A or 60A per phase depending on the tier, and a G100 export limitation scheme where required. Meet those and the answer is a yes or no on capacity, not a bespoke design study.

UK Power Networks, SSEN and National Grid Electricity Distribution describe three tiers. SGI-1 is notification only (16A per phase or less in total, Form A3-3). SGI-2 (up to 32A, export limited to 16A) and SGI-3 (up to 60A, export limited to 32A) are applications, each followed by Form A3-2 within 28 days of switch on.

One timing rule catches people out. On the fast track form the planned commissioning date 'shall be between 10 working days and three months from the date that the application is submitted to the DNO'. Your installation team cannot book you in for next week on the strength of an application sent today, and cannot leave it open ended either.

Operators' own published wording as at 18 August 2026. Northern Powergrid's electricity storage fast track document says it will assess the connection within 10 working days; Electricity North West publishes the forms but no working day turnaround.

The 45 working days is a regulated floor. Under Ofgem's guaranteed standards of performance an LV generation quotation is due within 45 working days, with £85 payable for each working day it runs late until dispatch (the sum Ofgem set on 13 March 2026 for failures from 1 April 2026, up from £80). That is roughly nine calendar weeks, and the point at which a silent standard G99 is officially late.

What causes delays

• Network constraints. A fast track answer is a yes or no on capacity. If the network cannot take the export, the application falls out to a quotation, and UK Power Networks cannot give a price or timeframe online for a supply upgrade because both are 'determined on the specific work required'.
• Incomplete forms. National Grid Electricity Distribution answers email and post submissions 'within 10 working days with the next steps'. Every published window assumes a complete application; a form that needs a query answered is not yet one.
• Batteries with island mode. The ENA guide is explicit: storage designed to operate in island mode takes the fast track off the table and 'the standard EREC G99 process applies'. Backup capable systems start on the 45 working day clock.
• Larger and three phase systems. The G98 limit is per phase, so a three phase home can fit up to 11.04kW under G98 and often avoids the wait. Above the fast track tiers, standard G99 Form A1-1 covers up to 50kW three phase or 17kW single phase on the 45 working day window.
• Export limiting left off the form. A G100 device is what lets a bigger inverter and battery stay on the fast track. UK Power Networks approves automatically where export after limitation is under 5kW; SP Energy Networks' storage relaxation needs export limited to 3.68kW per phase, total generation not above 7.36kW including the battery, and no island mode. Leave the limit off and the DNO assesses the full output.

How to avoid delays

Which DNO covers which region

Your electricity supplier is not your DNO, and the operator you deal with is fixed by where you live. The ENA identifies each by the Distributor ID at the start of your MPAN. Our guide to what a DNO is explains the difference; this is the map, and our county pages carry the local context.

Source: ENA, Who's my electricity network operator?, accessed 18 August 2026.

DNO pages and the ENA connection guide (March 2026, version 3.0) were checked on 18 August 2026. Response windows are the operators' published aims and regulated standards, not guarantees for a specific site.