Connecting a solar inverter to the grid: G98, G99, G100 and the ENA Type Test Register

A solar inverter exports power into the local distribution network, so your Distribution Network Operator (DNO) needs to know about it — and for larger systems, agree to it in advance. In Great Britain the rules come from the Energy Networks Association’s Engineering Recommendations. This guide explains which one applies to you and how the ENA Type Test Register fits in.

The rules at a glance

G98: the simple route

G98 applies when the installation stays within 16 A per phase ¹. On a 230 V single-phase supply — what most British homes have — that is 3.68 kW. Your installer can connect the system and then notify the DNO within 28 days of commissioning ¹.

That is why 3.68 kW inverters are so common here. In our database 13 of the 36 single-phase inverters are rated at 3.68 kW or less; the others (up to 6 kW) take a single-phase home into G99 territory. The panel array can be larger than the inverter; see sizing a solar inverter.

G99: ask first

Above 16 A per phase, G99 applies. The installer must get the DNO’s permission to connect before installing ¹. Plan for the DNO’s response time. Things that push you into G99:

• a single-phase inverter above 3.68 kW;
• battery storage above 3.68 kW, which needs its own G99 application (Form A1.1) before installation ¹;
• solar plus battery together exceeding 16 A per phase.

A fast-track G99 form (A1.2) also exists ¹. If your home has a three-phase supply, the 16 A applies per phase, so a three-phase inverter can deliver more before G99 kicks in. Our database has 47 three-phase models from 3 to 20 kW.

G100: capping export

Sometimes a DNO will accept a larger system if export is limited. The technical rules for such export (and import) limitation schemes are set out in ENA Engineering Recommendation G100 ². In practice, a meter at the supply point tells the inverter or battery to hold back when export reaches the agreed limit. Many hybrid inverters support this; 34 of the 58 models in our database with this data are hybrid. Ask your installer whether an export-limited G99 connection makes sense for you.

The ENA Type Test Register

The ENA Type Test Register is where manufacturers list equipment that has been type tested for connection to GB networks ³. Installers and DNOs use it to check that a model’s test documentation is in place, which keeps the notification process simple.

Part of our own inverter data comes from this register: for 24 models in our database, the AC rating, number of phases and whether the model is a hybrid are taken from ENA listings ³. When you compare models in our inverter comparison, you can see the source for each value.

Before you buy, ask your installer to confirm the exact model and variant is on the register — especially for imported or less common inverters.

Plug-in solar: 800 W and still G98

Plug-in solar kits became legal in Great Britain in August 2026. Under the government’s interim product specification ⁴:

• output is limited to 800 W per device, with one device per circuit protected by a circuit breaker at the consumer unit;
• kits are supplied complete with module(s), microinverter and cables;
• devices must be registered on the ENA Type Test Register before they are sold;
• products must comply with G98, which requires the consumer to notify the DNO.

See string vs micro vs hybrid for how microinverters compare with string systems.

Getting paid for export

The Smart Export Guarantee (SEG) lets you sell exported electricity to a supplier. It covers solar PV up to 5 MW in Great Britain, and payments are based on export meter readings ⁵. SEG tariffs are set by suppliers. Details in Smart Export Guarantee and VAT.

Checklist

1. Confirm your supply: single-phase or three-phase.
2. Size the inverter (and any battery) against the 16 A per phase G98 limit ¹.
3. If above it, allow time for a G99 application — or discuss export limitation under G100 ².
4. Check the inverter is on the ENA Type Test Register ³.
5. Make sure the installer notifies the DNO (G98) or has approval (G99) ¹.