Last updated 29 October 2026 · BrightEdge Solar team
Short answer: It comes down to size. G98 covers fully type-tested systems up to 16 A per phase, about 3.68 kW on a single-phase supply or 11.04 kW on three-phase. These can be connected first, with the network operator told within 28 days.[2] Anything bigger, batteries included, comes under G99. That means applying and getting approval before you install.[1][4] Most business systems need G99.
Before solar panels or a battery can run alongside the grid, your Distribution Network Operator (DNO) has to know about them. In Hull and East Yorkshire, that’s Northern Powergrid. Which form you use, and whether you can install before you hear back, depends on whether the system falls under G98 or G99. This guide compares the two for businesses, farms, schools, churches and homes. For how a G99 application actually runs, see our G99 application guide.
Key facts
- The dividing line is 16 A per phase. ENA says a generator under 3.68 kW per phase comes under G98, and anything above that comes under G99.[1] G98 puts 16 A at 3.68 kW single-phase and 11.04 kW three-phase.[2]
- G98 is “connect and notify”. The installer has to send the DNO the installation details no later than 28 days after commissioning.[2]
- G99 is “apply to connect”. The application goes in before installation, and it’s the owner’s responsibility to make sure the DNO has given authorisation before the work is done.[4]
- Batteries count. Battery storage is treated as generation, and the limits apply to everything at the site added together.[2][3]
- The DNO’s quote deadline is set by Ofgem. The guaranteed standard for a low-voltage generation connection quotation is 45 working days, or 65 working days at high voltage.[5]
G98 vs G99 at a glance
| G98 | G99 | |
|---|---|---|
| Size | Fully type-tested equipment up to and including 16 A per phase in total: about 3.68 kW single-phase or 11.04 kW three-phase[2] | Anything above 16 A per phase, plus equipment that isn’t fully type-tested[1][2] |
| When the DNO hears about it | After commissioning, within 28 days (“connect and notify”)[2] | Before installation, and you wait for approval (“apply to connect”)[4] |
| How long it takes | No wait before installing[2] | Fast-track routes for small battery and solar systems get an initial answer within 10 working days.[3] Otherwise, the DNO’s guaranteed standard for a quotation is 45 working days at low voltage[5] |
| Several installs close together | Apply first on G98 Form A, then send a Form B for each site within 28 days of commissioning[2] | No separate route. You apply before installing, as normal |
| Batteries | Count towards the 16 A per phase total[2] | Count towards the total, including for the fast-track routes[3] |
| Export limitation (G100) | Not needed | Can open the fast-track routes for small systems and help larger systems fit what the network can take[1][3] |
How to work out which one applies
It’s the inverter rating, not the panel wattage. For solar, the DNO goes by the inverter’s continuous rating. NGED’s example is a single-phase system with a 4 kW inverter: 4,000 ÷ 230 = 17.39 A, which is just over the 16 A limit, so it comes under G99.[6] G98 also lets a manufacturer limit an inverter’s rating using software settings the customer can’t change.[2]
Single-phase or three-phase matters. The limit applies to each phase, so a balanced three-phase system can go up to about 11.04 kW under G98.[2] Many farms and business premises have a three-phase supply. We check yours at the survey.
Add up everything on the connection. Count all the generation and storage behind one connection point together. If you already have solar fitted under the older G83 rules and adding more takes the total above 16 A per phase, G99 applies, and the DNO has to be consulted before the work starts.[2]
Batteries count towards the limit
G98 counts battery storage as a micro-generator, so it’s treated just like solar.[2] On a single-phase supply, a 3.68 kW solar inverter plus a separate 3.68 kW battery inverter adds up to well over 16 A, so the system can’t go through as a simple G98 notification.
G99 has three fast-track “Small Generation Installation” routes for this, provided every unit (storage included) connects through a fully type-tested inverter at a single installation:[3]
- SGI-1: the total stays at 16 A per phase or less, with any larger unit limited to 16 A. You install, then notify.
- SGI-2: each unit is 16 A or less and the total is under 32 A per phase, with a G100 export limitation scheme holding export to 16 A per phase. You apply on Form A1-2, and the DNO gives its assessment within 10 working days.
- SGI-3: each unit has a design capacity of up to 32 A and the total is under 60 A per phase, with export limited to 32 A per phase. Within 10 working days, the DNO confirms whether it needs to study your site further.
For SGI-2 and SGI-3, the planned commissioning date has to be between 10 working days and 3 months after the application.[3] Our battery storage page covers the equipment side, and the battery business case guide covers whether a battery pays for itself.
Export limitation (G100): a way to work within the limit
G100 is ENA’s technical guidance for export and import limitation schemes. These are controls that cap how much a site sends back to the grid.[1] An export limit doesn’t move a system back under G98. It’s still an application, made under G99 alongside the G100 paperwork.[3][4] What an export limit can do is open up the fast-track routes above for smaller systems. On commercial sites, it’s one of the options we look at, along with a battery or sizing to an existing approval, when the network can’t take full export. You still use everything you generate on site.
Where a fast-track route relies on G100, a separate G100 commissioning test form has to go to the DNO as well.[1]
Several installs close together: the G98 multiple-premises route
This matters for landlords, housing developers and estates with several properties. The simple G98 notify-after route doesn’t apply if the installer has fitted (in the previous 28 days), or plans to fit (in the next 28 days), other systems in the same “close geographic region”. The installer has to discuss the project with the DNO, apply first in the G98 Form A format, and connect only once the DNO has approved it and finished any network works. A Form B is then sent for each property within 28 days of commissioning.[2]
G98 defines a close geographic region as any one of these:[2]
- the area served by one low-voltage feeder from one transformer
- an area the DNO confirms
- premises whose postcodes match when the last two letters are ignored
- premises within 500 m of each other
Timescales you can plan around
- G98: there’s no wait before you install. The DNO has to be notified within 28 days of commissioning.[2] ENA Connect Direct is a free online platform for installers that covers all the UK DNOs, including Northern Powergrid. It can auto-approve an application when all of its checks pass.[7]
- G99 fast track: an initial answer within 10 working days, as above.[3]
- G99 standard: Ofgem’s guaranteed standard is a low-voltage generation quotation within 45 working days, or 65 at high voltage. If the DNO misses it, it makes a voluntary payment of £85 per working day late at low voltage (2026/27 rate).[5] In our experience, G99 typically adds 8–12 weeks before installation, and longer where the network is constrained. Our G99 application timeline goes through it stage by stage.
In practice: sizing to an existing G99 approval in Doncaster
At an 86 kWp rooftop system in Doncaster, the site already held a G99 approval granted for an older 60 kW unit. We sized the new SolarEdge SE66.6K Synergy inverter to fit within that approval, and a SolarEdge ONE Commercial Controller handles G99/G100 export limitation. We check for existing approvals at every commercial survey.
When this doesn’t apply
- Equipment that isn’t fully type-tested can’t use G98, however small it is. It goes through G99.[2]
- Systems built to run as an island or in parallel with the grid only for short periods are outside G98 and should follow G99.[2]
- One system supplying two or more independent customers through a sharing agreement has to apply under G99.[2]
- Larger sites face more G99 requirements, possibly including witnessed testing. See the G99 application hub and our commercial solar in East Yorkshire page.
- Outside Northern Powergrid’s area, the same ENA rules apply, but you deal with your local DNO, which may have its own way of taking applications.
Frequently asked questions
Do I need G98 or G99 for a 4 kW solar system?
On a single-phase supply, a 4 kW inverter works out at about 17.39 A, which is over the 16 A G98 limit, so it needs G99. A 4 kW system on a balanced three-phase inverter is well under 16 A per phase, so it can usually go through G98 as long as nothing else is connected.
Does adding a battery mean I need G99?
It can. Batteries count towards the 16 A per phase total, so solar plus a battery often goes over it. G99 has fast-track routes for small solar and battery systems, sometimes with an export limit. Where an application is needed, the DNO gives an initial answer within 10 working days.
Can I install solar before my G99 application is approved?
No. G99 is apply to connect, so the system shouldn’t be installed or commissioned until the DNO has approved it. The owner is responsible for making sure that approval is in place before the work starts. G98 systems can be connected first and notified within 28 days.
Who submits the G98 or G99 application?
Usually the installer. We prepare and submit the application, deal with any DNO questions and send the commissioning paperwork. Any DNO costs are shown separately in your quote.
Find out which route your site needs
Send us the address, a recent electricity bill or half-hourly data, and a photo of your electricity meter and main fuse. We’ll check the supply, size the system and tell you whether it’s G98, a G99 fast track or a full G99 application.
Book a free survey · Call 01482 765063
Sources
- Energy Networks Association, Connecting commercial generation to the electricity networks: https://www.energynetworks.org/industry/connecting-to-the-networks/connecting-generation-to-the-electricity-networks (checked 29 Oct 2026)
- Energy Networks Association, Engineering Recommendation G98 Issue 2 (2025), published by the Distribution Code: https://dcode.org.uk/assets/250307ena-erec-g98-issue-2-(2025).pdf (checked 29 Oct 2026)
- Energy Networks Association, Engineering Recommendation G99 Issue 2 (2025), section 6.2.2 Small Generation Installation procedures, published by the Distribution Code: https://dcode.org.uk/assets/250307ena-erec-g99-issue-2-(2025).pdf (checked 29 Oct 2026)
- GOV.UK, How to register energy devices in homes or small businesses: guidance for device owners and installation contractors: https://www.gov.uk/government/publications/register-energy-devices-in-homes-or-small-businesses-guidance-for-device-owners-and-installation-contractors/register-energy-devices-in-homes-or-small-businesses-guidance-for-device-owners-and-installation-contractors (checked 29 Oct 2026)
- Ofgem, Guaranteed Standards of Performance payment update 2026 (letter of 13 March 2026, DG Standards tables): https://www.ofgem.gov.uk/sites/default/files/2026-03/Guaranteed%20Standards%20of%20Performance%20payment%20update%202026.pdf (checked 29 Oct 2026)
- National Grid Electricity Distribution, G99 connection procedures: https://connections.nationalgrid.co.uk/g99-connection-procedures (checked 29 Oct 2026)
- Energy Networks Association, ENA Connect Direct: https://www.energynetworks.org/industry/connecting-to-the-networks/connect-direct (checked 29 Oct 2026)
