Engineering & Regulatory Standard

Commercial Solar G99 Application & G100 Export Limitation Guide

By HeatPumpsAndSolar.co.uk Commercial Technical Team · Published 21 October 2026 · Updated 29 October 2026

An export limit does not replace a generation connection approval.

Plan a commercial solar G99 application and G100 export limitation: inverter capacity, battery topology, DNO offer, commissioning and Northern Ireland differences.

Key Technical Principles

Check the AC ratings and topology of all generation and storage inverters before choosing the application route.
In Great Britain, G98 can cover eligible small generation; most larger commercial systems follow G99, with network consent before installation.
G100 limits export at the connection point but does not erase installed capacity, fault-level or protection checks.
Northern Ireland uses its own G98/NI and G99/NI routes through NIE Networks, including a distinct fast track requiring prior approval.

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Grid connection decision path

From AC capacity to connection approval

G100 export limitation is not a substitute for G99 approval. Programme and costs depend on the site and network operator; Northern Ireland uses separate NIE Networks routes.

Solar and battery inverters → site switchgearRecord total AC capacity, existing generation and protection settings for the connection application.

Building load ↔ point of connectionThe building uses some generation; a G100 export limiter, if accepted, monitors power crossing the agreed boundary.

Import/export meter ↔ DNO networkThe DNO agrees the connection and export limit. A limiter constrains export; it does not change inverter AC capacity or waive G99.

1
Define the system

List PV and battery inverter AC capacities, phase arrangement, existing generation and half-hourly site demand.
2
Choose the route

Confirm G98 or G99 with the network operator; assess a G100 export limit if the proposed export is constrained.
3
Submit and assess

Provide the single-line diagram, equipment and protection details. Allow for questions and a site-specific network assessment.
4
Review the offer

Check agreed export, any reinforcement, curtailment, charges and conditions before committing to the final design.
5
Test and hand over

Commission protection and any export limiter; complete required witness testing and retain the network approval and as-built settings.

Read the G99 and G100 guide →

Start with AC inverter capacity, not panel nameplate power

Your installer should list each existing and proposed PV inverter, battery inverter and other generator, with its continuous AC capacity and phase arrangement. Panel kWp is a DC generation rating and is not a substitute for the AC information in a grid application. A battery sharing a DC-coupled hybrid inverter can differ from a battery with its own AC inverter: the latter may add to aggregate inverter capacity and alter the application route. Ask for a single-line diagram showing the connection point and metering.

G98, G99 and G100: which question does each answer?

In Great Britain, eligible microgeneration up to 16 A per phase may use G98, subject to the route’s conditions; do not assume every small or multi-unit proposal is fit-and-notify. Larger schemes generally require a G99 application and network approval before installation. G100 governs an agreed export-limitation scheme, not permission to connect the generator. A zero-export setting still leaves installed inverter capacity and fault contribution for the network operator to assess.

From site data to approval and commissioning

Gather the supply identifier, supply arrangement, existing generation, proposed inverter data and half-hourly demand.
Have the engineer draw the single-line diagram, proposed export capacity and protection and battery configuration.
Submit the appropriate G99 application and G100 proposal if export limitation is needed; agree the route with the regional DNO before ordering installation around an assumed connection date.
Review the written offer for permitted export, reinforcement, curtailment, charges and conditions; compare the economics with a smaller array or different storage topology.
Install only under the agreed route, complete protection and export-limit testing and any required DNO witness test, then hand over as-built settings and connection documents before operation.

What a G100 export limit can and cannot do

A customer limitation scheme measures flow at the connection point and curtails output to meet the export limit agreed with the network operator. This may make a constrained site viable, but lost weekend or shutdown generation must be included in the business case. It cannot turn a large installed generator into a small one for fault-level, thermal or protection assessment. Ask the DNO to confirm the accepted capacity and whether reinforcement, flexible connection terms or a smaller design is needed.

Northern Ireland: check the separate NIE Networks route

NIE Networks administers G98/NI and G99/NI rather than the GB DNO process. Its fast-track rules changed on 1 May 2026: qualifying systems may have installed capacity up to 60 A per phase, subject to individual inverters no larger than 32 A and export no higher than 16 A per phase. Fast track still requires an application and approval before installation. Confirm the current scheme, permitted export and commissioning requirements with NIE Networks for your site.

Technical Compliance

Frequently Asked Questions

Facilities managers and engineering team queries

Does a G100 zero-export limiter remove the need for G99 approval?

No. G100 addresses export control, not connection approval. The network operator still checks installed inverter capacity, protection and fault contribution and must accept the proposed arrangement.

Do battery inverters count towards a commercial G99 application?

They can. A separate AC-coupled battery inverter may add to the capacity considered, while a battery sharing a hybrid inverter can be treated differently. Ask the engineer to show both arrangements on the single-line diagram.

How long will a commercial solar G99 connection take?

It depends on the application route, whether the submission is complete, network constraints and any required works or witness tests. Ask the network operator for the applicable offer and commissioning programme; do not treat a quotation target as an installation date.

Does Northern Ireland use the same G99 fast track as Great Britain?

No. NIE Networks has separate G99/NI criteria. Even a qualifying fast-track proposal requires approval before installation; check the current rules with NIE Networks.

Verify Your Facility's Grid & Compliance Status

Share the supply details, proposed inverter capacity and any battery plans. A network operator must confirm the actual connection route and conditions.

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