G98 Application Explained for UK Commercial Solar

A G98 application is how a fully type-tested generator up to and including 16 A per phase is registered with your Distribution Network Operator — around 3.68 kW on a single-phase 230 V supply, or 11 kW across a three-phase 400 V supply. Strictly it is a notification rather than an application: there is no application fee, no pre-approval and no waiting period, because the installer installs, energises, and then notifies the DNO within 28 days of commissioning. That threshold means G98 itself covers domestic and genuinely micro installs: almost every commercial solar PV project — offices, retail units, workshops, schools — goes through G99 instead. The good news is that G99 is not one monolithic process. Fully type-tested systems up to 17 kW per phase (around 50 kW on a balanced three-phase supply) qualify for a streamlined fast-track application with much quicker DNO turnaround, while larger arrays follow the full study-offer-acceptance route. This page explains exactly how a G98 application works, what your installer submits and what evidence to demand, why your project probably needs G99, and how the fast-track keeps sub-50 kW commercial installs moving at sensible speed.

Which route applies to your system

Three routes exist and only the first is a G98 application. The deciding number is always amps per phase, assessed on the inverter AC output rather than the panel DC rating, so an oversized array does not push a system up a band. Read the row that matches your inverter, not your ambition.

The single most common mistake is assuming size alone decides the paperwork burden. It does not — sequencing does. G98 is the only route where the system can be generating before the DNO has heard of it. Both G99 routes are apply-before-connect, so a project that discovers its route late loses weeks it did not budget for. And to settle the question people most often arrive here with: a 50 kW system is G99 fast-track, not G98 — 50 kW is roughly 17 kW per phase, more than four times the G98 ceiling.

What G98 actually is

Engineering Recommendation G98 (current version Issue 1 Amendment 7, 2026) is published by the Energy Networks Association on behalf of the six UK distribution network operators. It governs the connection of fully type-tested micro-generators rated up to and including 16 A per phase — roughly 3.68 kW on a single-phase 230 V supply, or 11 kW across a three-phase 400 V supply — to the public low-voltage distribution network. Crucially, G98 is a connect-and-notify standard: provided the inverter is on the current type-test register and the installation meets the standard requirements (protection settings, anti-islanding, voltage and frequency trip envelopes, earthing), the installer simply installs, energises, and notifies the DNO within 28 days. There is no application study, no pre-approval, no offer or acceptance step, no witness test, and no DNO fee — the notification is a free registration. This is the framework that keeps domestic and micro-scale PV moving at sensible speed. For anything bigger, the question is not whether you need G99 — it is which G99 route applies.

How G98 differs from G99 — and why the threshold matters

The boundary between G98 and G99 is sharp. G98 covers fully type-tested generation up to and including 16 A per phase; G99 covers everything above it. The two regimes are operationally very different. G98 is connect-and-notify: no pre-approval, no fee, install and energise first, notify within 28 days. G99 is apply-before-connect in every case — but it splits into two routes. Fully type-tested systems up to 17 kW per phase (around 50 kW on a balanced three-phase supply) qualify for the streamlined G99 fast-track: a simplified application, usually with no separate assessment fee, and much quicker DNO turnaround — weeks rather than months — before energisation. Above 17 kW per phase, the full G99 application applies: a formal DNO study, a connection offer, acceptance, network reinforcement where needed, scheduled connection works, and a witness test before energisation — total timeline 6-18 months, fees £1,500-£15,000+, possible network reinforcement charges of £30k-£250k+.

For a commercial project the threshold that matters is therefore the fast-track ceiling, not the G98 limit. A 45 kW type-tested system on a balanced three-phase supply (15 kW per phase) sits inside the G99 fast-track and connects in weeks. A 60 kW system (20 kW per phase) on the same supply tips into the full G99 process and runs materially longer. The marginal generation from those extra kilowatts rarely justifies the extra months of timeline and the additional fees — unless the project is large enough that full G99 was inevitable anyway. We always size against this threshold deliberately at design stage.

The G98 process step by step

From contract signing to system live generating, the typical sequence runs:

Stage 1: Pre-installation desk check

Before signing contract, we run a desk-based check of which route the project takes: a system at or below 16 A per phase (~3.68 kW single-phase / ~11 kW three-phase) qualifies for G98 connect-and-notify; anything larger — which means almost every commercial array — is scoped for the G99 fast-track or full G99 route instead. We also confirm supply phasing matches the design, the MPAN is active, and no known network constraint exists at the postcode. This stage is built into our quote process — no charge, no separate step.

Stage 2: Inverter type-test verification

Every inverter on the proposed system is cross-checked against the DNO's current type-test register. We only specify inverters with valid certification. If a customer has a preference for a specific brand or model not on the register, we either swap to a compliant equivalent or — rare — lodge a G99 application instead. Specifying uncertified inverters under G98 is non-compliant and we don't do it.

Stage 3: Physical install

Mounting, panels, DC cabling, inverter installation, AC cabling, switchgear, isolators — all happen on the customer's site without any DNO involvement. Typical install duration for a genuine G98 micro system is 1-3 days. No waiting for offers, no scheduling around DNO works.

Stage 4: Commissioning and energisation

System is energised by the installer (no DNO witness required under G98), generation begins, customer's bills start to fall. Commissioning paperwork is completed including protection settings record, type-test certificates package, single line diagram, MPAN reference, and customer details.

Stage 5: 28-day notification

The notification is lodged with the DNO within 28 days of energisation through their connection portal. The DNO acknowledges within 5 working days and processes the notification within 4-8 weeks. They may request clarification on protection settings or earthing — we resolve any queries promptly. The notification is registered, the DNO updates their network records, and SEG (Smart Export Guarantee) registration with the energy supplier follows.

What the installer actually submits with a G98 application

Most guides stop at "your installer notifies the DNO". That is true but useless when you are the one signing the contract, so here is the practitioner detail — who lodges it, what is in the pack, what you should insist on seeing, and what actually happens when the deadline slips.

Who submits it — the installer, not the customer

The duty sits with the installer, and in practice with the MCS-certified contractor who commissioned the system. You are not the applicant, you do not sign anything before energisation, and you should be wary of any installer who asks the customer to lodge their own notification. Under G98 the DNO registers rather than approves — a compliant notification cannot be refused — so there is no negotiation for you to take part in. The flip side is that the paperwork is invisible unless you ask for it, which is exactly why unnotified systems exist.

The document pack

A complete G98 notification lodged through the DNO connections portal contains:

• The ENA G98 notification form — Form B for a single premises; Form A is the variant used where several premises are notified together.
• Site and metering identifiers — full site address and the MPAN the generation sits behind.
• Inverter data — make, model, rated AC output, number of phases and the resulting amps per phase (the number that decides the route).
• The type-test certificate reference — proving the exact inverter model is listed on the Energy Networks Association Type Test Register under the current EREC G98 issue.
• A single line diagram showing the generator, isolation, protection and the point of connection.
• Protection settings — the voltage and frequency trip envelopes and anti-islanding arrangement as commissioned.
• Commissioning date and installer credentials — the commissioning date is what starts the 28-day clock.
• Export limitation details, where fitted — if the system is constrained to a lower export figure, the limitation scheme forms part of the picture the DNO is registering.

What to ask your installer for as evidence

Treat these as handover conditions rather than favours, and hold a retention until they arrive:

1. The DNO acknowledgement with its reference number, in writing. This is the document people mean when they ask for a "G98 certificate" from the network side, and your energy supplier will ask for the reference at Smart Export Guarantee registration.
2. A copy of the submitted notification form, so you can check the inverter model, kW rating and MPAN actually match what is on your roof.
3. The inverter type-test certificate for the exact model installed — certificates expire, and a model certified in 2024 is not automatically certified in 2026.
4. The commissioning record and protection settings sheet, which is what any future contractor will need before touching the system.
5. The MCS installation certificate, which your supplier requires for SEG alongside the DNO reference.
6. The single line diagram as installed, not as designed.

What happens if the 28-day notification is missed

Lodge it late rather than never — DNOs accept retrospective notifications and would far rather hold accurate network records than none. But an unnotified system carries four real consequences. First, the DNO assesses voltage rise and fault level on the generation it knows about, so your array is simply absent from that model, and so is everyone else who did the same on your feeder. Second, Smart Export Guarantee registration usually stalls, because suppliers ask for the DNO reference — export income you are entitled to sits unclaimed. Third, if the late notification then reveals non-compliant protection settings or an inverter that is not on the type-test register, the DNO can require rectification and, in the extreme, disconnection until it is put right — a far more expensive conversation after the scaffolding has gone. Fourth, it surfaces at sale: a buyer solicitor asks for the grid-connection evidence during conveyancing, and a missing pack becomes a price negotiation. If you have inherited a building with undocumented PV, the fix is a competent contractor reviewing the installation against the current standard and lodging the notification retrospectively.

What G98 costs you

The G98 notification itself is free in 2026 — DNOs process it, update the register, and handle any minor clarifications without charge. The only cost is nominal installer admin time to prepare the pack. There are no study fees because there is no DNO study, and no network reinforcement charges because a 16 A per phase system is small enough that no reinforcement is contemplated. The assessment fee sometimes attributed to G98 actually belongs to the G99 fast-track application — the simplified route for type-tested systems up to 17 kW per phase (~50 kW), varying slightly by DNO with UK Power Networks and SP Energy Networks at the higher end and Northern Powergrid at the lower. Either way, we roll all connection admin into the install quote so the customer never sees a separate DNO invoice — just one fixed-price quote covering everything from design through energisation. At typical UK commercial pricing of £900-£1,200 per kW a 50 kW project runs £45,000-£60,000, so even at the top of the range the fast-track fee is around 1% of project cost or less — small enough that it is rarely worth dwelling on.

Type-test verification — which inverters comply

Every G98-eligible inverter must hold valid type-test certification under the current EREC G98 Issue 1 Amendment 7 standard — and the same type-testing regime is what unlocks the G99 fast-track for systems up to 17 kW per phase. The Energy Networks Association maintains a public Type Test Register listing every certified model and the certificate expiry. Common compliant brands and ranges across the G98 and G99 bands in 2026:

• SolarEdge: HD-Wave residential range, Energy Hub small commercial up to 33 kW three-phase — the latter sits inside the G99 fast-track band at 11 kW per phase.
• SMA: Sunny Boy residential range, Sunny Tripower X, Sunny Tripower CORE1 and CORE2 up to 110 kW (the larger CORE models are full-G99 territory).
• Fronius: Symo Advanced range covering 3-20 kW, GEN24 range, Tauro 50-100 kW industrial inverters.
• Huawei: SUN2000 commercial three-phase range up to 100 kW, FusionSolar managed inverters.
• Sungrow: SG three-phase commercial range, particularly SG33CX, SG50CX, SG110CX (SG33CX and SG50CX sit inside the G99 fast-track band at 11 and ~16.7 kW per phase; SG110CX is full-G99 territory).
• Solis, GoodWe, Solplanet: Multiple commercial three-phase models on the register.

We cross-check every quote against the live register before lodging. Type-test certificates expire — sometimes a model that was compliant in 2024 has lapsed in 2026 — so we never rely on previous knowledge.

When G98 doesn't work

Three scenarios complicate the route choice even when the system size looks straightforward.

Network capacity issues. If your local 11 kV substation is heavily loaded with existing PV connections, even a small system can attract DNO scrutiny — and a G99 fast-track application on a constrained feeder can be knocked back into the full study process on grounds of voltage rise or thermal capacity. The DNO heat map (UK Power Networks Capacity Map, NGED Network Capacity Map, SSEN DFES) shows where these constraints exist. In a constrained postcode the project either resizes downward, lodges as full G99 from the start, or accepts an ANM curtailment offer.

Fault level concerns. Older 11 kV substations can hit fault current limits when too much inverter generation is added. The DNO will protect the network by refusing additional generation capacity on that feeder. This is uncommon for small commercial PV but real on some constrained urban networks — we check at desk-study stage.

Per-phase imbalance. Both thresholds are assessed per phase, not on the total. A balanced 10 kW three-phase system (~3.3 kW per phase, about 14.5 A) sits just under the G98 16 A per phase limit, but the same 10 kW dumped onto one phase is roughly 43 A and needs G99. The same logic bites in the G99 fast-track band: a 48 kW system spread 24/14/10 across three phases breaches the 17 kW per phase fast-track ceiling on phase one, even though a balanced 16/16/16 layout would qualify. Balanced design avoids this — every commercial PV system we install distributes inverters across all three phases as evenly as possible.

The single-phase trap

The G98 16 A per phase rule has a brutal implication for commercial sites with single-phase supplies. A small office, retail unit, or workshop on a single-phase 230 V supply can only host ~3.68 kW of PV under G98 — a handful of panels in 2026 module sizes. Anything larger needs a G99 application, and even the G99 fast-track caps a single phase at 17 kW. The genuine commercial answer is almost always a three-phase upgrade: it lifts the G98 ceiling to ~11 kW and, far more usefully, opens the G99 fast-track to ~50 kW of type-tested PV. Three-phase upgrades typically cost £3,000-£15,000 depending on the distance from the nearest three-phase mains and the local DNO connection charges. The economics decision is straightforward: if the site can usefully host 30-50 kW of PV (large roof, high daytime energy use), the upgrade is worth it because the additional generation pays back £4,000-£6,000 per year of savings, recovering a £3,000-£15,000 upgrade cost inside four years — and often inside one — before counting the PV. If the roof can only take a few kW (small roof, modest energy use), staying single-phase with a micro G98 install is usually the right call.

Three-phase upgrade considerations

Upgrading from single-phase to three-phase requires the DNO to install a new three-phase service from the nearest mains location to your meter position. Cost factors: distance from the three-phase mains (urban: typically 10-50 metres, suburban: 30-150 metres, rural: 100+ metres), whether the cable is overhead or underground, whether civils work (trenching, reinstatement) is needed, and the headroom on the local transformer. Typical 2026 ranges: £3,000-£8,000 for a short urban upgrade and £8,000-£15,000 for a mid-distance suburban one — which is where the £3,000-£15,000 headline range quoted above comes from. Long rural upgrades sit outside that band at £15,000-£30,000. Some rural sites are simply not viable for a three-phase upgrade and that limits the economic case for solar.

For sites where the customer is committing to a substantial PV install we usually time the three-phase upgrade application in parallel with the PV design — both processes can run together so the upgrade is complete before the PV install begins. Asset finance can roll the upgrade cost into the PV finance package, which our finance options page covers in detail.

Inverter selection for G98 compliance

Beyond bare type-test compliance, three considerations drive inverter selection on a G98 commercial system. Phase configuration. Most modern commercial inverters above 5 kW are three-phase by design — single-phase inverters above ~5 kW are increasingly rare in the European market. We design the system to balance load across all three phases regardless of inverter selection. String configuration and oversizing. Panel DC capacity can exceed the inverter's AC rating (DC:AC ratio of 1.1-1.25) to maximise annual yield — both the G98 16 A per phase limit and the G99 fast-track 17 kW per phase ceiling are assessed on the inverter's AC output, not the panel DC rating, so oversizing the array does not breach either threshold. Monitoring and remote management. SolarEdge, SMA, Huawei and Sungrow all offer cloud-based monitoring stacks that surface generation data and alarm conditions to your facilities team — we always include this on commercial installs because problems caught in week one save thousands compared with problems caught at year-three service review.

What happens after the 28-day notification

Once the DNO has acknowledged and processed the notification, your system is registered on the network records. SEG (Smart Export Guarantee) registration with your chosen energy supplier follows — most suppliers process SEG registration within 14 days of receiving the G98 confirmation. SEG export tariffs range roughly 4–12p per kWh as at July 2026 depending on supplier, with Octopus Energy and EDF among the higher-paying options. Annual MCS or NICEIC certification renewal happens for the installer (not the customer). Generation data flows to the SEG meter via a dedicated export MID or, more commonly in 2026, via a smart meter export channel.

Authority resources and standards

The Energy Networks Association publishes the canonical G98 standard and update register: Energy Networks Association — Distributed Generation. The MCS framework certifies installer competency for sub-50 kW PV: MCS Certified. Ofgem regulates SEG export tariffs and the DNO charging framework: Ofgem SEG. UK government net zero policy context: gov.uk Net Zero Strategy.

Related decision pages

If your project is above 16 A per phase — as almost every commercial array is — see G99 application process. To quantify whether the project earns its keep, read are commercial solar panels worth it. To compare solar against alternatives at the same budget, see solar vs alternatives. For larger sector hubs see industrial solar panels, factories, warehouses, or offices. To understand the wider cost picture see our cost guide, and for funding see grants and funding. For battery storage paired with commercial PV, see battery storage.