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StandardsG98 or G99: which one applies, what the application involves, and how long it takes
Adding a battery to a solar system pushes most homes over the G98 threshold and into a G99 application, which means asking the network operator's permission before the work happens rather than telling them afterwards.
Updated 4 August 2026 · written by the Clearline guidance team
The line, and which side of it you are on
Your Distribution Network Operator owns the wires in your street, and it decides what you are allowed to connect to them. Two Energy Networks Association engineering recommendations govern it. G98 covers the connection of fully type tested micro-generators up to and including 16A per phase. G99 covers the connection of generation equipment in parallel with public distribution networks above that.
Sixteen amps per phase is 3.68kW at a nominal 230 volts. That single number decides whether your installation is fit and notify, or apply and wait.
| G98 | G99 | |
|---|---|---|
| Threshold | Up to and including 16A per phase, which is 3.68kW at 230V | Above 16A per phase, or anything that does not meet G98 requirements |
| Three phase equivalent | Aggregate up to the per phase limit | Aggregate above 11.04kW |
| Process | Install and commission first, then notify | Apply first, and get acceptance before commissioning |
| Deadline | G98 Installation Document and Operation Diagram within 28 days of commissioning | Prior DNO acceptance, timescales below |
Sources: National Grid Electricity Distribution G98 and G99 connection procedure pages, accessed August 2026. Three phase figure from a secondary installer source.
It is the inverter, not the panels
The rating that counts is the inverter's continuous AC rating, not the size of the array on the roof. A 3kW inverter draws 13.04A at 230V and sits inside G98. A 4kW inverter is 17.39A and falls outside it. Aggregate rating means the sum of all generating plant at the property, including a battery that can export.
Your installation team handles the DNO application, but the system size decides which route you take. A free remote design call sizes it properly before anything is submitted.
Get your free quote →Why a battery so often tips you over
A hybrid or AC coupled battery inverter adds to the aggregate capacity at the property. That is why a modest solar array that would have sailed through G98 on its own frequently pushes a home over 3.68kW and into G99 the moment storage is added.
This is not a reason to skip the battery. It is a reason to design the whole system at the start rather than in phases, because one application for what you actually want beats a second application in two years. Our guide to sizing a solar and battery system works through the order that saves money.
Where the local network is constrained, a G100 export limitation scheme can cap how much the system is allowed to push back to the grid, which sometimes keeps an application viable that would otherwise be refused. It limits export, not generation or self consumption.
What a G99 application actually involves
In a standard domestic job you do not submit it. The installer handles the network operator application, because every DNO process page is written for installers and requires technical detail from the design. What you should expect is to be told which route applies and to be given a copy of the acceptance when it arrives.
For smaller systems there are simplified routes rather than the full application. Power generating modules up to 50kW three phase or 17kW single phase use the simplified application, Form A1-1, or the Fast Track forms A1-2 where the equipment is type tested. Larger systems use the standard application form, with capacity bands running from Type A under 1MW up to Type D at 50MW and above. Domestic work sits comfortably in the simplified routes.
How long it takes
There is a regulated answer and a practical answer, and you should know both.
The regulated timescale
Under the Ofgem set connection guaranteed standards of performance, the quotation timescale for a low voltage generation connection is 45 working days, with a failure payment of £85 (from 1 April 2026) if it is missed. Budget estimates below 1MVA are 10 working days. These standards took effect in April 2024, under the Electricity (Connection Standards of Performance) Regulations 2015 as amended in 2023.
The practical answer is usually faster for a straightforward domestic job. Several DNOs publish a 10 working day target for fast track decisions on type tested systems under 50kW, with full applications running 8 to 16 weeks where the local network is constrained. Treat those as indicative ranges from market experience rather than commitments, and treat the 45 working day standard as your backstop.
What G98 asks for, if you stay under the line
G98 is a fit and notify process for a single premises: the installer may install and commission first, then must submit a G98 Installation Document and an Operation Diagram within 28 days of commissioning. The criteria behind it still have to be met.
- Type tested equipment
- Grid interface protection installed and tested
- A system that shuts down in a power cut
- A lockable isolation switch
- A circuit diagram displayed on site
One trap is worth knowing about. Multiple premises within 500 metres of each other, installed within 28 days of each other, must use the G98 Multiple Premises process, which requires agreement with the network operator before installation. If you and three neighbours book the same firm in the same fortnight, that is the rule that applies.
Not sure whether your system is a G98 or a G99? Book a free remote design call and we will size it and tell you.
Get your free quote →Who is my DNO?
It is not your electricity supplier. Your supplier sells you the units; the DNO owns the cables. You can find yours from the postcode lookup published by the Energy Networks Association, or from your electricity bill. Which DNO you sit under affects how quickly applications are turned around, which is one of the reasons our county pages carry local calculators and local context.
Before you sign anything
Ask which route the design needs
G98 or G99, and on what aggregate rating. If the quotation does not say, the design is not finished.
Get the timeline in writing
If it is a G99, ask what the expected acceptance window is and what happens to your installation date if it slips.
Check export limitation
If a G100 scheme is proposed, understand what it caps and what that does to your export income.
Keep the acceptance
The DNO notification or acceptance belongs in your document pack alongside the MCS certificate. A conveyancer will ask for it.
Clearline never installs. Applications and installations are handled by an MCS-certified installation team for your area, and our role is to make sure the design that goes to the network operator is the one you actually want. If you are still weighing the system up, start with solar panels or EV charging.
Thresholds, forms and timescales were checked against National Grid Electricity Distribution and Energy Networks Association material in August 2026. Individual DNO processes and current queues vary by region.
DNO application questions
What is the difference between G98 and G99?
G98 covers fully type tested micro-generation up to and including 16A per phase, which is 3.68kW at 230 volts, and works on a fit and notify basis with paperwork submitted within 28 days of commissioning. G99 applies above that threshold, or where G98 requirements are not met, and requires the network operator to accept the application before commissioning.
Does a battery push me into G99?
Very often, yes. A hybrid or AC coupled battery inverter adds to the aggregate generating capacity at the property, so a modest array that sat inside G98 alone can cross 3.68kW once storage is added. It is one reason to design the full system at the start rather than in stages.
How long does a G99 application take?
Under the Ofgem set connection guaranteed standards of performance, the quotation timescale for a low voltage generation connection is 45 working days with an £85 failure payment (from 1 April 2026). In practice, several DNOs publish a 10 working day fast track target for type tested sub 50kW systems, and 8 to 16 weeks on full applications where the network is constrained.
Do I submit the application myself?
Not in a standard domestic job. Every DNO process page is written for installers, and the application needs design detail only the installer has. Ask to be told which route applies and to be sent a copy of the acceptance or notification once it is done.
Do I have to pay my DNO to connect solar panels?
For a straightforward domestic connection under the simplified routes, the application itself is part of the installation team's process rather than a separate homeowner charge. Where network reinforcement is required, costs can arise, which is why you want to know early whether your connection is constrained.
What is G100?
G100 is an export limitation scheme. It caps how much electricity the system is permitted to export to the grid, which can keep an application viable on a constrained connection. It does not limit what the system generates or what you use yourself, but it does affect export income.
Who is my DNO?
The distribution network operator for your area, which is not the same as your electricity supplier. Find it from the Energy Networks Association postcode lookup or from your electricity bill. The DNO decides connection applications and its regional workload affects timescales.
See the numbers next: Tesla Powerwall 3, installed, or the battery storage guide.
Figures and specifications in this guide are sourced below and were checked on the date shown. Rates and product specifications change; we confirm the current picture on your free design call.
Sources
- National Grid Electricity Distribution, G98 connection procedures: threshold, 28 day notification, rating maths, 500m rule connections.nationalgrid.co.uk
- National Grid Electricity Distribution, single premises micro-generation G98: fit and notify criteria connections.nationalgrid.co.uk
- National Grid Electricity Distribution, G99 connection procedures: scope, fast track forms, capacity bands connections.nationalgrid.co.uk
- Ofgem, connection guaranteed standards of performance letter (13 March 2026): LV generation quotation 45 working days, £85 failure payment from 1 April 2026 connections.nationalgrid.co.uk
- Energy Networks Association, EREC G98 and G99 documents, forms and find your DNO energynetworks.org
- Energy Networks Association, DNO metered connections standards of performance, April 2024 energynetworks.org
- Installer guidance on three phase thresholds and battery aggregation, indicative market timings mandsrenewables.com
- Installer guidance on G100 export limitation renew-able.co.uk
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