G98 vs G99: which grid connection route your business needs

The short answer

Both are Engineering Recommendations published by the Energy Networks Association. Your installer prepares the notification or application; the figures below are from National Grid Electricity Distribution (NGED) and NIE Networks, checked on 3 November 2026.

G98: fit and notify

NGED describes G98 as "a simple connection procedure for fully type tested installations under 16A per phase", installed on a fit and notify basis. Its criteria include:

• The rated output is under 16A per phase, connected at low voltage
• Interface protection is installed and tested, and the system shuts down in a power cut
• There is a lockable isolation switch for all phases, and a circuit diagram on site
• The network operator is notified within 28 days of commissioning

Source: NGED micro generation (G98). For a business, G98 rarely covers more than a token array: 11.04 kW of panels on a three-phase supply is a small fraction of most commercial roofs.

G99 fast track: the middle ground

NGED runs a G99 fast track for small installations, in three categories (NGED fast track):

All equipment must be type tested and the installation must be on an existing premises. If an SGI-3 study does not meet the requirements, the application is processed as a standard G99 enquiry.

G99 standard: apply first

Most commercial systems go through a standard G99 application. NGED's guidance sets out the stages (NGED G99 connection procedures):

1. Planning. Early talks with the operator, and if you want one, a budget estimate (a desktop figure, no site visit) or a chargeable feasibility study.
2. Application. Systems under 50 kW apply on a shorter form (A1-1); larger ones use the standard application form with site plans, equipment data and, where used, an export limitation application.
3. Connection offer. The operator sets out the works needed and their cost. NGED's offers are valid for 90 days, with a possible single extension of a further 90 days if you ask in writing.
4. Construction and commissioning. For larger systems, a Power Generating Module Document is kept up to date through the build, and tests and paperwork follow within 28 days of first connection.

G99 also sorts generation into types by size. NGED's guidance gives Type A as greater than 800W and less than 1MW, and Type B as 1MW to less than 10MW. Nearly every rooftop system is Type A; the paperwork grows with the type.

What it means for your project timeline

• Start the grid question early. The survey checks your supply, switchboard and likely route, so the application is complete when it goes in. Incomplete applications are a common cause of delay; see G99 and DNO applications.
• Do not order equipment before the offer on a standard G99 project. The offer may come with conditions, a lower export figure or works.
• Consider an export limit if the network is constrained. It can turn a long wait into a quicker connection; see G100 export limitation.
• Batteries count. Storage is assessed alongside the solar, so include it in the application from the start; see battery storage.

Northern Ireland

NIE Networks uses its own versions of the same routes (NIE Networks):

• G98/NI covers up to 16 amps per phase, 3.68 kVA single-phase or 11.04 kW three-phase.
• G99/NI Fast Track covers up to 60 amps per phase, with individual inverters limited to 32 amps per phase and export limited to 16 amps per phase. Its parameters changed on 1 May 2026.
• G99/NI covers everything larger.

Get the grid question answered

A free survey checks your supply and tells you which route your system is likely to need before you commit. See what you qualify for.