G98 Application Process for Commercial Solar

G98 is the UK's connect-and-notify framework for fully type-tested micro-generation up to and including 16 A per phase — around 3.68 kW on a single-phase 230 V supply, or 11 kW on a three-phase 400 V supply. 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 G98 works, why your project almost certainly needs G99, and how the fast-track keeps sub-50 kW commercial installs moving at sensible speed.

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, a fee of typically £350-£500, 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 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 £350-£500 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, even the fast-track fee is well under 1% of project cost — 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 (the larger CX models are 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) sits comfortably under the G98 16 A per phase limit, but the same 10 kW dumped onto one phase exceeds it 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 the upgrade cost in 1-3 years 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 short urban upgrades, £8,000-£15,000 for mid-distance suburban upgrades, £15,000-£30,000 for long rural upgrades. 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 in 2026 range 4-15p per kWh 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.