G99 Explained: When Solar and Battery Systems Need DNO Approval First

G99 is the Energy Networks Association engineering recommendation for larger generating systems, and it requires approval from your distribution network operator (DNO) before you connect. If your solar panels, battery or both can send more than the G98 limit of 16A per phase onto the grid, you are generally in G99 territory rather than the simpler connect-and-notify route.

For most households the question never comes up, because a single plug in solar kit and many home batteries sit comfortably below that line. This guide explains what triggers G99, which forms are involved, and how to plan a plug in solar or battery setup that stays within G98.

What is a G99 application and why does it need prior approval?

A G99 application is a request to your DNO to connect generation that falls outside G98's small-scale limits. The key difference is timing. Under G99, the network operator reviews your proposal before anything is energised, rather than being told after the event.

Larger exports can affect the local network you share with neighbours, so the operator checks capacity first. G98, by contrast, is described on the Anker SOLIX UK product page as connect and notify: the electrician informs the DNO within 28 days of commissioning.

How does G99 differ from G98 in practice?

• G98: small generation up to 16A per phase, about 3.68kW on a single-phase supply, connected first and notified within 28 days, per the Anker SOLIX UK product page.
• G99: anything larger, or anything that cannot meet the G98 conditions, applied for and approved before connection.
• Plug in solar: DESNZ says the government is amending G98 so that IPS-compliant plug in solar microgenerators can connect to low-voltage networks.

What typically triggers the G99 regulations for a home?

Strictly, G99 is an engineering recommendation rather than a law, but people often call it the G99 regulations because DNOs apply it as the rulebook for larger connections. Guidance generally describes three common household triggers, though you should check the current edition with your DNO:

• Output above 16A per phase: if your inverters can together export more than the G98 threshold, guidance points towards G99.
• Combined solar and battery export: a solar inverter and a battery inverter that are each modest can, added together, take the property over the limit.
• Equipment that is not type tested: G98 is generally described as requiring fully type-tested kit listed on the ENA Type Test Register, so unlisted equipment is usually steered towards G99.

None of these usually applies to plug in solar on its own, but they all matter once plug in solar shares a home with larger kit.

Can plug in solar ever trigger G99?

According to the Energy Saving Trust, a UK-compliant plug in solar device is limited to about 800W, which is far below the G98 ceiling. The government is bringing plug in solar under an amended G98, not G99. EST also notes that the current rules do not allow daisy chaining several plug in solar devices, although the government is looking at permitting more than one per home in future.

The picture changes when plug in solar sits alongside other generation. If you already have a hardwired battery or a rooftop array, ask your DNO how the combined output is assessed before adding anything.

Which G99 form applies to your project?

There is no single G99 form. The Energy Networks Association publishes several, and guidance generally describes these routes for smaller properties. Check the current versions on the ENA website before anything is submitted:

1. Form A1-1: a simplified application for Type A generation up to 17kW single-phase or 50kW three-phase.
2. Form A1-2: a fast-track route for integrated micro-generation and storage up to 32A per phase where export limitation is used.
3. Standard Application Form: for larger or more complex schemes that do not fit the simplified routes.
4. Form A3-2: the commissioning form completed once the approved system has been installed and tested.

In practice, your installer completes the G99 application form and submits it, which guidance indicates is often done through the ENA Connect Direct portal.

Plug in solar owners will not normally touch any of these forms. The government's plan is for IPS-compliant plug in solar to connect under G98, and its safety study recommended a simplified registration approach for plug in solar.

What are the core G99 requirements for homeowners and installers?

The G99 requirements themselves are technical, and your installer handles most of them. As a homeowner, it still helps to know the broad shape:

• Approval before connection: the DNO must agree to the connection before the system is switched on.
• Accurate equipment details: inverter ratings, battery capacity and any export limitation settings must be declared.
• Commissioning evidence: once installed, the commissioning paperwork confirms the system was set up as approved.
• Wiring rules still apply: G99 sits alongside, not instead of, Part P and BS 7671 for the electrical work itself.

None of these steps is relevant to a typical plug in solar purchase. They matter when you commission a sizeable rooftop array, a large battery, or both.

What role does export limitation under G100 play?

G100 is generally described as the ENA recommendation for customer export limitation schemes. It lets a system with larger inverters cap how much it sends to the grid, which can make an otherwise oversized setup suitable for a fast-track G99 route. Ask your installer whether an export limit would suit your plans, and confirm the approach with your DNO.

How can you stay within G98 and avoid a G99 application?

For most homes, staying below the G98 threshold is the simplest path. A few planning habits help:

2. Add up every inverter at the property, including solar, battery and any plug in solar kit, rather than judging each device alone.
3. Choose equipment that is type tested and listed on the ENA Type Test Register, which guidance generally treats as a G98 condition.
4. Size the battery inverter to your evening needs rather than picking the largest model.
5. Keep plug in solar to a single compliant device, as the current rules expect.

AC output is the figure that matters most here. The table compares several batteries with a typical plug in solar kit.

Figures come from each brand's official UK store and, for the panel-only kit, the Energy Saving Trust, all checked on 30 October 2026; prices change often, so re-check them before you buy.

Why does the Solarbank 4 E5000 Pro fall under G98 rather than G99?

Anker addresses the G99 question directly. Its UK product page reports that the Solarbank 4 E5000 Pro has passed G98 certification and appears on the official listing, and it explains the arithmetic: a maximum AC output of 2,500VA works out at 10.9A, comfortably under the 16A-per-phase line. On that basis Anker says a standalone unit sits in the G98 route rather than needing a G99 application.

That does not make it a plug in solar product. It is a 5,024Wh LiFePO4 battery, per the official Anker SOLIX datasheet, and the government's IPS covers plug in solar without batteries. The unit is built plug-in ready at hardware level, but plug connection is not currently permitted, so it must be hardwired rather than treated like plug in solar.

• Installation: a Part P-registered electrician connects it on a dedicated hardwired circuit to the consumer unit, paired with the Anker SOLIX Smart Meter Gen 2.
• Notification: the electrician submits G98 documentation to the DNO within 28 days of commissioning, which can be done through ENA Connect Direct.
• Output: the factory default is 800W, and the 2,500W setting is only available after the hardwired installation and grid notification, once you email proof to Anker support for an unlock password.

Before you book an electrician, read the certification details and wiring requirements set out for the Anker SOLIX Solarbank 4 E5000 Pro home battery, then ask your installer to confirm the route against everything else already connected at your address.

Could adding panels or batteries push an existing system into G99?

Yes, and this is where many homeowners get caught out. Guidance generally treats the G98 limit as applying to the whole property, so a system that qualified on day one may not stay there after an upgrade.

The official Anker SOLIX datasheet lists support for one to five Solarbank units in parallel. Several units at full rated output would add up to more than the roughly 3.68kW single-phase G98 figure, so expanding a Solarbank system, or pairing it with an existing rooftop inverter, needs checking first.

What should you ask before expanding?

• Will the combined output at my address stay within G98, or will a G99 application be needed?
• Would export limitation keep the system on a simpler route?
• If I add plug in solar later, how will it be counted alongside my battery?

This article is general guidance rather than legal advice, so confirm the specifics with your electrician, your DNO and your energy supplier before you buy. If you are comparing options, the Solarbank 4 E5000 Pro specifications and G98 details are a useful benchmark for a battery that stays on the simpler route.

Conclusion

G99 is the right process for large or complex systems, and it protects a network everyone relies on. For a single plug in solar device or one sensibly sized home battery, it is rarely needed. The point to watch is growth: each new inverter adds to the total your DNO sees, so plan expansions before you buy, and keep your connection paperwork together for future installers.

If you want hardwired storage that stays under the G98 threshold, explore the Anker SOLIX Solarbank 4 E5000 Pro and talk to a Part P-registered electrician about your home.

Frequently Asked Questions

Who submits a G99 application, the homeowner or the installer?

In most cases your installer prepares and submits it, because the application needs technical equipment details and, later, commissioning evidence. You remain the customer at the address, so the DNO may contact you directly. Keep copies of everything sent, as future buyers or installers may ask to see the approval records.

Can I switch on a system while its G99 application is still pending?

No. The defining feature of G99 is prior approval, so the system should not be energised for export until your DNO has agreed the connection. Your installer can complete the physical work, but commissioning and switch-on wait for the operator's confirmation. This differs from G98, where notification follows installation.

Is G99 approval the same thing as an MCS certificate?

No. G99 approval comes from your network operator and concerns connecting generation to the grid. An MCS certificate is a quality-mark record that a certified installer completed the work, and many suppliers ask for one before paying export tariffs. A large rooftop system may need both, whereas plug in solar needs no G99 application.

Does a three-phase supply change when G99 is needed?

It can. The G98 limit is expressed as 16A per phase, so a three-phase home generally has more headroom than a single-phase one. Guidance commonly quotes about 11.04kW across three phases, but treat that as a figure to confirm with your DNO, because your installer should check the exact supply at your address.

Will unlocking the Solarbank's 2,500W output require G99?

According to the Anker SOLIX UK product page, no. The unit's maximum AC output of 2,500VA sits below the G98 threshold, so it is notified under G98. The higher setting becomes available only after a Part P-registered electrician hardwires it and the DNO is notified, and you then email installation proof to Anker support.

Does G99 apply in Northern Ireland in the same way?

Not necessarily. DESNZ notes that connection rules in Northern Ireland differ, with separate safety regulations and a G98/NI version, and the plug in solar changes there remain subject to the Northern Ireland department's consideration. If you live in Northern Ireland, check the current process with your local network operator before planning solar or battery work.