G98 Explained: The UK Grid Connection Standard for Plug-In Solar Systems

As plug-in solar becomes a more accessible option for UK homes, understanding how these systems connect to the electricity network is increasingly important. G98 explained: the UK grid connection standard for plug-in solar looks at how Engineering Recommendation G98 applies to eligible small-scale generation systems, including some plug-in solar installations, and explains the key grid connection requirements for safe operation in the UK.

Before connecting a plug-in solar kit, you should check whether the system meets the relevant requirements, including inverter compliance, output limits and any required DNO notification. These checks help ensure that connected generation operates safely and provides accurate information to the local electricity network.

alt: G98 explained the UK grid connection standard for plug-in solar

What Is Engineering Recommendation G98?

Engineering Recommendation G98 sets out the requirements for connecting small-scale generators, including solar PV systems, micro-inverters, and some inverter-based energy systems, to the UK distribution grid. Managed within the Energy Networks Association (ENA) framework, it provides a standard process for connecting microgeneration safely and consistently across the network.

The key G98 threshold is 16 amps per phase. For most UK single-phase homes, this represents approximately 3.68kW of AC inverter output at 230V. The limit applies to the inverter output rather than the solar panel rating. Most flats, terraced homes, semi-detached properties, and standard detached houses use single-phase supplies, while some larger or rural properties may have three-phase connections.

An 800W plug-in solar kit with a compliant type-tested inverter is typically well below the G98 threshold and may be suitable for the standard G98 route. However, if the system follows the G98 route, it must use a compliant inverter and be notified to the relevant Distribution Network Operator (DNO) within 28 days of commissioning.

What G98 Means for Plug-In Solar

Understanding these points helps you check whether your solar setup is suitable for a standard G98 connection route and whether any additional assessment may be needed.

The Key G98 Rule in One Sentence

For plug-in solar, the main G98 requirement is that the system must stay within the 16A per phase limit, use approved type-tested equipment, and be notified to the local Distribution Network Operator (DNO) within 28 days of commissioning. These rules apply to many eligible small-scale solar systems connected to the UK grid.

The 3.68kW Single-Phase Limit

The 3.68kW single-phase limit represents the practical output boundary linked to the 16A per phase threshold at standard UK voltage. Most UK homes use single-phase electricity supplies, so this limit is especially relevant when choosing a plug-in solar system or planning future expansion.

The 28-Day DNO Notification Requirement

Under G98 rules, eligible small generators can usually connect first and notify the DNO afterwards. The notification should normally be submitted within 28 days of commissioning. Your DNO manages the local electricity network, while your energy supplier handles your tariff and billing.

The Inverter Safety Requirement

The inverter plays a key role in G98 compliance because it converts solar DC electricity into AC power for household use. It must meet technical requirements for voltage, frequency and disconnection. Anti-islanding protection means the inverter stops exporting electricity during a grid outage.

G98 vs G99: Which Grid Connection Standard Applies?

G98 and G99 are UK grid connection standards for different types and sizes of electricity generators. The main difference is the level of technical assessment required before connection. G98 is generally used for smaller microgeneration systems within the permitted limits, while G99 applies to larger or more complex installations that require further review by the DNO.

When Plug-In Solar Normally Falls Under G98

Many plug-in solar systems may fall under G98 when the inverter output remains below the 16A per phase limit and the equipment has been type-tested for UK grid connection requirements.

Balcony solar kits and compact home solar systems are typically designed around these conditions. An 800W plug-in solar kit with an 800W AC inverter output, for example, is well below the G98 threshold. However, you should always check the inverter output rating rather than looking only at the solar panel wattage.

When a Solar System May Need G99 Approval

A solar system may require a different connection assessment, such as G99, when the output exceeds G98 limits or when the installation is more complex and requires further DNO review.

Larger rooftop solar installations and higher-capacity battery systems may need additional assessment before connection. G99 can also become relevant when multiple generation sources are combined, as the total generation and export capacity of the complete system may need to be assessed.

Why Larger Systems Require More Assessment

Larger generators can have a greater impact on the local electricity network, including voltage levels, fault conditions and available network capacity. The DNO may need to assess whether local cables, transformers and protection systems can support the additional generation.

For this reason, G99 normally requires approval before connection, while G98 usually follows a notification process after commissioning. The correct route depends on the size, design and technical specification of your system.

G98 Rules and Compliance Checklist for Plug-In Solar

Before connecting a plug-in solar system, check these key requirements to understand whether your setup meets the main G98 rules.

Maximum Output Below 16A Per Phase

Check your system output

• The inverter output must remain below the 16A per phase limit for G98.
• For most UK single-phase homes, this equals approximately 3.68kW AC output.
• If multiple inverters or solar systems are installed at the same property, check the combined export output.

Type-Tested Micro-Inverter on the ENA Register

Check your inverter certification

• Confirm that your inverter model is listed on the ENA Type Test Register.
• Check that the model number matches your product label and technical documents.
• Do not assume similar-looking products meet UK grid connection requirements.

Anti-Islanding Protection During Power Cuts

Check inverter safety features

• The inverter must include anti-islanding protection.
• The system should stop exporting electricity when the grid supply fails.
• Check the inverter’s G98 type-test documents to confirm this safety function is included.

No Fee for Standard G98 Notification

Understand DNO notification requirements

• A standard G98 notification is usually submitted to the DNO without a connection assessment fee.
• Extra costs may apply if:
• your installation needs electrical upgrades
• your system exceeds G98 limits
• your setup requires G99 approval

Documents and Details to Keep

Prepare your compliance records

Keep copies of:

• DNO notification confirmation
• Inverter datasheet and model number
• ENA Type Test Register evidence
• Installation and commissioning date
• User manual and safety information
• Electrical certificates (if applicable)
• Battery storage documentation

When combining solar generation with battery storage, check the inverter configuration and total export capacity to confirm whether the system remains within G98 requirements.

Conclusion

G98 explained: the UK grid connection standard for plug-in solar comes down to a few practical checks: stay within 16A per phase, use a compliant inverter, and notify your DNO within 28 days of commissioning. For many small UK plug-in solar kits, especially an 800W system, the process is usually straightforward.

Before connecting your kit, check the inverter rating and confirm it appears on the ENA Type Test Register. If you have battery storage, multiple inverters, or an existing solar array, ask a qualified electrician or installer to confirm whether G98 or G99 applies. Keep your DNO confirmation and compliance documents with your home energy records.

FAQs

Is plug-in solar equipment legal in the UK?

Solar equipment may be legal in the UK when it meets applicable electrical safety and grid connection requirements. However, battery storage systems are currently not permitted to connect through a standard household socket in the UK. Battery storage installations must follow UK Building Regulations Part P and be completed by a Part P-registered electrician using a hardwired connection to the consumer unit.

Does an 800W solar generation system need G98 notification?

Yes, an 800W plug-in solar kit normally needs G98 notification because it connects a generator to the electricity network. The output is usually well below the 16A per phase threshold, so it will often fit the standard G98 route. The notification should be submitted to your DNO within 28 days of commissioning.

For battery storage systems, G98 requirements do not replace UK installation requirements. Battery systems must still follow Part P installation rules and be connected through an appropriate hardwired installation method.

Do I need DNO approval for plug-in solar?

For eligible G98 plug-in solar, you usually need DNO notification rather than prior approval. This means the system can often be commissioned first and reported within 28 days. If the system exceeds 16A per phase, uses non-type-tested equipment, or forms part of a larger setup, G99 approval may be needed before connection.

How do I check if my inverter is G98 compliant?

Check the inverter model against the ENA Type Test Register and compare the exact model number with your product label or datasheet. A compliant inverter should have G98 type-test evidence and built-in safety functions, including anti-islanding protection. If you cannot find the model, ask the supplier for UK-specific compliance documents before connecting it.