G98 is the UK's connect-and-notify framework for distributed generation up to 17 kW per phase or 100 kW total. For most small and medium commercial solar PV projects — offices, single retail units, smaller workshops, schools — G98 means the system can be installed and energised without waiting for distribution network operator pre-approval. The installer notifies the DNO within 28 days of commissioning and the connection is registered. No study fees, no network reinforcement, no 6-18 month timeline. This page explains exactly how it works, when G98 is the right route, and when the project size or supply configuration tips into G99 territory instead.
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 generators rated up to 17 kW per phase or 100 kW total 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 notifies the DNO within 28 days of energisation. There is no application study, no pre-approval, no offer or acceptance step, no witness test, and no DNO connection charges beyond a small admin fee. This is the framework that keeps small-scale PV moving at sensible commercial speed.
How G98 differs from G99 — and why the threshold matters
The boundary between G98 and G99 is sharp. G98 covers up to 17 kW per phase / 100 kW total. G99 takes over at 17.001 kW per phase or 100.001 kW total. The two routes are operationally very different. G98 is connect-and-notify, no pre-approval, 4-8 weeks of post-energisation notification administration, costs £350-£500 in fees, and the project commissions within 8-12 weeks of contract. G99 requires 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 project sitting near the threshold this matters enormously. A 96 kW install on a balanced three-phase supply (32 kW per phase) sits cleanly inside G98 and energises in 8-12 weeks. A 110 kW install (37 kW per phase) on the same supply triggers G99 and runs 6-15 months. The marginal generation from those extra 14 kW rarely justifies the extra year of timeline and the additional fees — unless the project is large enough that 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 that the proposed system fits within G98 thresholds: total kW under 100, kW per phase under 17, supply phasing matches design, MPAN active, no known network constraint 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 1-3 weeks for a sub-100 kW commercial system. 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 DNO administration fee for a G98 notification is typically £350-£500 in 2026, varying slightly by DNO. UK Power Networks and SP Energy Networks sit at the higher end, Northern Powergrid at the lower. This fee covers the notification processing, register update, and any minor clarifications. There are no study fees because there is no DNO study. There are no network reinforcement charges because the system is small enough that no reinforcement is contemplated. We roll the £350-£500 into the install quote so the customer never sees a separate DNO invoice — just one fixed-price quote covering everything from design through energisation. For sub-100 kW installs at typical UK pricing of £900-£1,200 per kW, the DNO 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. The Energy Networks Association maintains a public Type Test Register listing every certified model and the certificate expiry. Common compliant brands and ranges in 2026:
- SolarEdge: HD-Wave residential range, Energy Hub small commercial up to 33 kW three-phase, multiple sub-100 kW models all currently certified.
- SMA: Sunny Tripower X, Sunny Tripower CORE1 and CORE2 range up to 110 kW (latter sits at the G99/G98 boundary, so used cautiously).
- 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 (which sits at G99 boundary).
- 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 force a project from G98 into G99 even when the proposed system size suggests G98 should apply.
Network capacity issues. If your local 11 kV substation is heavily loaded with existing PV connections, the DNO may refuse to register a G98 notification 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 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 G98 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. A 96 kW total install spread 60/30/6 across three phases breaches the 17 kW per phase rule on phase one and is non-compliant under G98 even though total kW sits under 100. 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 17 kW 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 100 A supply can only host ~17 kW of PV under G98 — about 60 panels in 2026 module sizes. Anything larger forces G99 or a three-phase upgrade. 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 50+ kW of PV (large roof, high daytime energy use), the upgrade is worth it because the additional ~33 kW of 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 site can only host 25 kW (small roof, modest energy use), staying single-phase with a 17 kW 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. An 80 kW PV array can run on 75-95 kW of inverter capacity; over-sizing the panels relative to the inverter (DC:AC ratio of 1.1-1.25) maximises annual yield without breaching G98. 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 100 kW, 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 sub-100 kW PV, see battery storage.
G98 application — common questions
What is the G98 connect-and-notify process?
G98 is a streamlined notification process for connecting type-tested generators up to 17 kW per phase / 100 kW total to the UK low-voltage distribution network. Unlike G99, no DNO pre-approval is required before energisation — the installer simply notifies the DNO within 28 days of commissioning. As long as the inverters hold valid G98 type-test certificates and the system meets standard requirements, the connection is automatic.
How long does a G98 connection take?
The notification itself is processed in 4-8 weeks by the DNO. However, because no pre-approval is required, the physical install and energisation can happen as soon as the project is built — there is no waiting period. The 4-8 week notification window happens after the system is already generating. In practical terms, a G98 install can be commissioned within 8-12 weeks of contract signing, compared with 6-18 months for an equivalent G99 install above 100 kW.
How much does a G98 application cost?
Typically £350-£500 for the application administration, including the DNO notification, single line diagram, type test certificates and protection settings package. This is rolled into the install quote — no separate invoice. There are no DNO study fees on G98 because no DNO pre-approval is required, and no network reinforcement charges because the system size is small enough to fit any reasonably healthy distribution network.
Which inverter brands are G98 type-tested in 2026?
Every inverter we specify holds current G98 Issue 1 Amendment 7 type-test certification. Common compliant brands in 2026: SolarEdge (HD-Wave, Energy Hub residential and small commercial), SMA (Sunny Tripower CORE2, STP), Fronius (Symo, Tauro), Huawei (SUN2000), Sungrow (SG series three-phase), Solis, GoodWe, Solplanet. The DNO publishes a public Type Test Register and we cross-check every model on every project. Specifying an uncertified inverter would invalidate the G98 route and force the project into G99 — adding 6-18 months of process for no benefit.
When is my project too big for G98?
Above 17 kW per phase or 100 kW total across all phases, G98 stops working and G99 takes over. On a three-phase 400 V supply that means 100 kW total balanced (33 kW per phase). On a single-phase 230 V supply you cap at 17 kW (about 60 panels) — most commercial sites with single-phase supplies hit this constraint and need either to size down, accept G99 admin, or upgrade to a three-phase supply at £3,000-£15,000.
What if my DNO refuses the G98 notification?
Refusal is rare but possible if the DNO identifies a network constraint that breaches G98 thresholds for voltage rise, fault levels, or thermal capacity. In those cases the system can usually still be installed but the application is reclassified as G99 — adding 6-12 months of process and possibly reinforcement charges. We pre-screen every G98 site against the DNO heat map before commissioning to avoid this. If a constraint exists, we lodge G99 from the start rather than risk G98 refusal mid-build.
Do I need a three-phase supply for G98 commercial solar?
Not strictly — G98 covers single-phase up to 17 kW. But in practice, most genuine commercial sites benefit from a three-phase supply because (a) it lets you install up to 100 kW under G98 instead of capping at 17 kW, (b) it improves voltage stability and reduces nuisance trips, and (c) it provides headroom for future expansion. Three-phase upgrade typically costs £3,000-£15,000 depending on supply distance and DNO charges. We always model whether the upgrade earns its keep against a larger PV array or whether to stay single-phase and cap the system.