G98 vs G99 — NIE Networks grid rules in plain English

Why NI grid rules matter

If you install solar — with or without a battery — that can export to the public network, you are connecting generation to NIE Networks. The route depends mainly on capacity installed and how much you may export.

Northern Ireland uses G98/NI and G99/NI. These are not identical to every GB blog post, and the Smart Export Guarantee (SEG) does not apply here. Grid connection and export payments are related but separate — see solar export payments in Northern Ireland.

Fee figures below follow NIE Networks Statement of Connection Charges V1.16 (effective 1 July 2026). Charges change — confirm on your quote.

What G98/NI is

G98/NI covers micro-generation: small, type-tested equipment under a "fit and inform" process.

For many homes that means the installer fits and commissions an approved micro-generator, notifies NIE Networks (Stage 1) — typically within 30 days of commissioning — NIE Networks may arrange an import/export-capable meter if needed, and you arrange an export tariff with your electricity supplier (NIE does not buy your power).

G98 fees and Stage 2

Within these limits with type-tested kit, G98/NI is usually the path. Above them → G99/NI.

Application fee: £0 to submit G98/NI Stage 1 or Stage 2. Stage 2 may still trigger network reinforcement costs if NIE's study finds them.

G98/NI Stage 2 applies when NIE must assess the local network first (e.g. certain multiple installations nearby). Capacity is still G98-scale; Stage 2 timescale depends on job size and volume. Your installer should flag Stage 2 if it applies.

What G99/NI is

G99/NI covers generation that does not qualify for G98 fit-and-inform. Critically: approval before installation — not install-then-notify.

Since 1 May 2026, NIE Networks splits G99 more clearly into Fast Track and full G99.

G99/NI Fast Track

Streamlined G99 when published criteria are met (re-check live NIE pages): Total Installation Capacity (TIC) up to 60 A per phase ≈ 13.8 kW; individual inverter limited to 32 A ≈ 7.36 kW; export limited to 16 A per phase ≈ 3.68 kW (often via G100 export limitation) — larger arrays for self-use are common.

Still application-and-approval. Incomplete packs stay outside the queue until valid.

Connection Application Fee (CAF), Schedule 2: £311 ex VAT (£373.20 at 20% VAT) for Fast Track, per Statement V1.16.

Timescales: NIE's licence standard is to issue an offer within 3 months of a valid application and fee. Installers often report roughly ~20 working days once the pack is valid — that shorter figure is installer experience, not a published NIE FAQ SLA, so treat it as typical practice rather than a guarantee. Once you have an offer, acceptance is usually within 90 days.

Full G99/NI (above Fast Track)

Exceeds Fast Track limits or fails Fast Track criteria → fuller design, quotation and connection agreement. Common for larger commercial arrays and sites needing network studies or reinforcement.

Larger schemes (≥ 5 MW) may attract additional SONI charges. Offer within 3 months of a valid application (the Utility Regulator can extend that licence period). Accept within 90 days.

Domestic vs larger / three-phase

• ~3–3.68 kW single-phase home — often G98/NI if type-tested and within 16 A per phase (£0 application fee).
• Larger domestic (e.g. 5–10 kWp) with export capped ~3.68 kW — frequently G99/NI Fast Track (£311 ex VAT CAF) or full G99 if criteria fail.
• Three-phase homes, farms, small commercial — G98 can stretch to ~11.04 kW. Beyond that, expect G99, CAF from the table above, and longer lead times.
• Batteries — parallel storage can change the route via aggregate registered capacity. Design solar and storage together. See whether a home battery is worth it in Northern Ireland.

Who files the paperwork?

You remain the generator. Suppliers pay for export; NIE Networks owns the connection process.

B9 Renewables handles NIE notifications and applications as part of a normal install, with work by NICEIC-approved electricians. Ask any contractor which route applies before you sign.

Lead-time honesty

If the design needs G99, put grid approval in the programme. Do not book scaffold and hope the letter arrives.

Commercial and farm note

• Export may be constrained even if roof space is not.
• NIE CAF / possible reinforcement sit outside panel price — see how much solar panels cost in Northern Ireland.
• Agreements, milestones and queue position matter more than on a simple G98 house job.
• Export income is still voluntary supplier tariffs, not SEG — model self-use first.

Money and support (separate from grid forms)

• No SEG in NI — grid approval is not a GB-style export scheme.
• Export signup follows NIE steps — see solar export payments in Northern Ireland.
• Grants/VAT are separate — see solar panel grants and support in Northern Ireland. Eligible domestic installs may attract 0% VAT until 31 March 2027 (unless extended); that does not change which grid form you need.