CONSIDERED HOME ENERGY TOOLKIT
G98 / G99 Export Limitation Checker
Add up the export-capable AC capacity of your solar inverter, battery and any other generation to see whether you're a straightforward G98 notification or over the threshold into G99 territory — plus a separate, honest answer to "does adding an EV charger or heat pump push me into G99?" (short version: usually not, but they matter for a different reason).
✓ Totals AC inverter capacity, not DC panel size — the figure that actually decides G98 vs G99
✓ Separates export/generation capacity from added load, rather than conflating the two
✓ Flags the double-counting trap between DC-coupled and AC-coupled batteries
Not a substitute for your installer's or DNO's own assessment. This is a quick, honest steer using the same threshold your installer will check — not a formal G99 application or a network capacity study. Already checked your generation capacity and want to size a system in the first place? Try the Solar & Battery Size Finder. Checking a plug-in kit specifically? See the Plug-In Solar Payback Calculator.
1. YOUR SUPPLY
Single-phase or three-phase?
Almost all UK homes are single-phase. Three-phase is mostly larger properties, some rural supplies, or homes that have specifically requested an upgrade.
2. GENERATION & EXPORT-CAPABLE KIT
What can actually push power onto the grid
This is what G98/G99 is actually about — the combined AC output rating of everything capable of exporting, not what's on your roof.
3. EV CHARGER & HEAT PUMP
These are loads, not generation
They don't count toward the G98/G99 export threshold above — but they still draw a lot of power, and a big jump in what you're pulling from the grid is its own separate DNO conversation about supply headroom. Answer these for an honest, informational steer on that.
Your result
Export / generation status
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Total export capacity—
Your threshold—
ℹ
⚠Already have generation installed and adding more? This threshold applies to your total combined export capacity at the property, not just the newest device — enter everything you'll have once the new kit is in, not just what's being added.
Common mistakes
- Double-counting a DC-coupled battery that already shares its inverter with the solar figure above.
- Using DC panel wattage instead of the inverter's AC output rating — a 6kW of panels behind a 3.68kW inverter is still G98.
- Assuming an EV charger or heat pump pushes solar/battery from G98 into G99 — they're loads, not generation, and don't count toward this threshold.
- Forgetting existing generation when sizing an addition — the threshold is about your total, not the new device alone.
- Treating a G98 notification as optional because there's no fee — it's still a legal requirement, due within 28 days.
- Assuming G99 approval is guaranteed or quick — DNOs can take several weeks and can, in some cases, refuse or require network reinforcement.
Not sure what size you need yet?Work out a solar and battery size range first
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Check electrical compatibilityPanel, microinverter and wiring compatibility, separate from DNO rules
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See the assumptions used
Illustrative only, not a formal DNO assessment. Real G99 decisions, fees and timescales depend on your specific network's spare capacity, which varies street to street. Regulatory details reflect our understanding as of 10 August 2026 and may have changed since — always confirm with your installer and your own DNO before buying or installing anything.
THE PART MOST GUIDES SKIP
What actually counts toward G98/G99, and what doesn't
The confusion is understandable — "generating capacity" sounds like it should include anything electrical you're adding. It doesn't.
✓ Counts toward the threshold
- Solar inverter AC output rating — the figure that actually limits export, regardless of how much DC panel sits behind it.
- Battery or hybrid inverter AC rating — if it's a separate, AC-coupled unit from your solar inverter. If it shares the same hybrid inverter as your solar (DC-coupled), it's already included in that inverter's single AC rating.
- Any other export-capable generation at the same connection — a wind turbine, a second inverter, and so on. All of it, combined, existing plus new.
✕ Doesn't count toward the threshold
- DC solar panel wattage — only the inverter's AC output rating matters here, not how many panels sit behind it.
- Battery storage capacity (kWh) — how big the battery is has no bearing on G98/G99; only its inverter's power rating (kW) does.
- EV chargers and heat pumps — these draw power (import), they don't export it, so they sit outside the G98/G99 generation threshold entirely. They can still matter for a separate reason: a big new load can eat into your property's spare supply capacity, which is a conversation about your main fuse and network headroom, not about export limitation.
This is a genuinely under-documented area — several official and installer-facing sources describe the export side clearly but say little to nothing about how EV chargers and heat pumps interact with it, which is exactly why this tool keeps the two questions separate rather than guessing at a combined number.
THE THRESHOLD ITSELF
G98 vs G99, in numbers
Both routes exist so DNOs can manage how much generation connects to a shared local network without checking every single small installation individually.
G98 — "fit and notify"For combined export capacity up to 16A per phase (3.68kW single-phase, ~11.04kW three-phase). No prior approval, no fee — your installer notifies the DNO within 28 days of connecting.
G99 — prior approvalRequired once combined export capacity goes over that threshold. The DNO has to approve the connection before it goes live, checking it against local network capacity. Can take several weeks, and larger or non-standard applications can carry a fee.
Fast-track routes existSmaller over-threshold systems can sometimes use a simplified "Smaller Generating Installation" fast-track process rather than a full G99 application — ask your installer whether your system qualifies.
Export limitation (G100)An alternative to a full G99 upgrade: keep larger generation or storage but cap how much can actually export, electronically limiting it back under the threshold your network can accept.
⚠Three-phase isn't simply "three times the headroom" in practice. The 11.04kW three-phase figure assumes a perfectly balanced load across all three phases. A three-phase supply with generation concentrated on one phase can still be constrained by that single phase's 3.68kW limit — worth flagging to your installer if your setup isn't evenly split.
NOTIFYING YOUR NETWORK OPERATOR
Notify your network operator
Whether it's a G98 notification or a G99 application, it goes to your regional electricity Distribution Network Operator (DNO) — usually submitted by your installer on your behalf. Great Britain has six network companies covering fourteen regional licence areas:
UK Power NetworksLondon, the South East and the East of England
National Grid Electricity DistributionThe Midlands, the South West and South Wales
SP Energy NetworksCentral & southern Scotland, Merseyside, Cheshire and North Wales
Northern PowergridNorth East England and Yorkshire
Electricity North WestGreater Manchester, Lancashire, Cumbria and parts of Cheshire
SSENNorthern Scotland, plus Hampshire, Berkshire, Oxfordshire, Wiltshire and Dorset
These are broad areas, not precise postcode boundaries. Use the Energy Networks Association's own lookup to confirm your exact DNO: energynetworks.org — find my network operator.
In Northern Ireland, distribution is run separately by NIE Networks and these GB thresholds don't automatically apply the same way — check nienetworks.co.uk instead.
How this tool works
The export/generation verdict sums three inputs — solar inverter AC rating, a separately AC-coupled battery/hybrid inverter's AC rating (deliberately excluded if you said your battery shares a hybrid inverter with your solar, to avoid double-counting), and any other generation — and compares the total against 3.68kW for a single-phase supply or 11.04kW for three-phase (3.68kW × 3, assuming a reasonably balanced load across phases). At or under the threshold shows as G98; over it shows as needing G99. A result within 5% of the threshold is shown as borderline, since real inverter nameplate ratings, rounding and DNO interpretation can tip a close call either way — that's a "check with your installer" case, not a confident green or red.
The EV charger and heat pump section is deliberately kept separate and qualitative rather than folded into the same number. They're consuming loads, not export-capable generation, so they don't belong in the G98/G99 calculation at all — several installer-facing and official sources describe the export side of this clearly but say little about how added load interacts with it, so rather than invent a combined threshold this tool gives an honest, informational steer instead: your selected EV charger and heat pump power ratings are compared against your main fuse rating (using a simplified assumption that other everyday household load already uses a meaningful share of that fuse's headroom) to flag whether it's likely fine, worth a proper check, or likely to need your installer to assess supply capacity or discuss an upgrade — not a real diversity-factor calculation, which only a qualified installer can do properly.
Typical power figures used: a standard single-phase EV charger is 7kW (32A); a three-phase EV charger can be 7kW or up to 22kW; a typical air source heat pump draws roughly 2–4kW of electrical input at design conditions (more with immersion/electric backup heating in use); ground source and larger heat pumps can draw more. These are broad, commonly-cited figures, not a substitute for your specific product's rated input current.