Get G100 Right: Commissioning and DNO Steps for UK Export Limitation

Most UK homes are limited to exporting the regulatory threshold of 16A per phase, which equals 3.68 kW on a single-phase supply, and export limitation schemes (CLS) built around G100 are the standard way network operators let larger solar and battery systems connect without waiting for grid reinforcement. If you are planning a bigger system, the practical next step is contacting your local DNO or a certified installer to confirm your Maximum Export Limit (MEL) and the right application route before you order equipment.

TL;DR:

Homes with export limits of 16A per phase typically have a maximum export of 3.68 kW on single-phase connections, affecting how larger systems are configured.

Larger installations exceeding the 16A threshold should apply for a G99 connection approval instead of a simple G98 notification, often requiring a full application process.

Export limitation schemes measure and control power at the physical connection point, usually through inverter settings or external controllers, with fail-safe responses within 5 seconds being mandatory.

The paperwork process for approval involves submitting specific forms within 45 days and commissioning within 28 days post-energization, with regional variations mainly affecting application forms and response times.

Implementing export limits generally causes only modest clipping losses, which can be mitigated by batteries and load shifting, making it a cost-effective choice for typical domestic systems.

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What an export limitation scheme is and why DNOs use it
Standards and thresholds: EREC G100, G98 and G99 explained for UK homes
How export-limitation schemes operate: hardware, control logic and fail-safe behaviour
DNO application and approval process: forms, timelines and common connection conditions
Practical homeowner implications: clipping, batteries and export payments
Installer checklist: steps to design, install and certify a compliant G100 scheme
Differences between export limitations in various UK regions
Implications of export limitation on energy tariffs and potential financial impact
Future developments or expected regulatory changes affecting export limitations in the UK
Common challenges or compliance issues faced by installers and homeowners
A practical view from the field on export limitation
How we can help with export limitation, solar and battery projects
FAQ
Sources

What an export limitation scheme is and why DNOs use it

A Customer Export Limitation Scheme, usually shortened to CLS, caps the amount of power a property can push back onto the network at the point of common coupling, the physical connection between your installation and the local grid. Distribution Network Operators accept this cap as a condition of connection because it lets them manage local network capacity without rebuilding cables or substations every time a household installs a larger solar array.

Export limitation is not the same thing as a generation connection permission. A device still has to meet G98 or G99 requirements in its own right, while G100 governs how the whole site’s export is measured and controlled.

A CLS reduces how much power leaves the site, not how much the inverter can generate for home use.
DNOs favour export limitation over reinforcement because it avoids long waiting lists and large upstream costs.
Generation connection approval (G98/G99) and export limitation (G100) are separate but related requirements on the same project.

Standards and thresholds: EREC G100, G98 and G99 explained for UK homes

Three documents govern most domestic export decisions. EREC G100 Issue 2 Amendment 2, published by the Energy Networks Association, sets the technical requirements for CLS behaviour, including fail-safe operation and reaction times. G98 covers straightforward micro-generator connections, and G99 applies once capacity exceeds the G98 notification threshold.

G98 covers single premises up to 16A per phase, which is the figure behind most domestic export discussions.
Above that threshold, an installation typically needs a full G99 application rather than a simple notification.
A CLS defines both a Maximum Export Limit and, in some designs, a Maximum Import Limit, with short permitted excursions above MEL built into the scheme’s tolerance.

The 16A per-phase threshold equals 3.68 kW on a single-phase supply and 11.04 kW on a three-phase supply. Crossing that line on either supply type generally moves a project from a quick notification process into the longer G99 application route.

How export-limitation schemes operate: hardware, control logic and fail-safe behaviour

A CLS measures power at the exit point of the installation, the physical boundary with the network, rather than measuring each individual inverter. Three approaches are common on domestic and small commercial sites.

Some inverters include a built-in export limit setting, which is often the simplest option for a single-inverter system.
Larger or multi-inverter sites often use an external controller reading current sensors or a smart meter feed to coordinate several devices.
Hybrid systems sometimes combine inverter limits with a central controller for redundancy.

National Grid’s guidance on export limitation confirms that a compliant scheme must reduce exported power to the agreed MEL within a short reaction window if a component or signal fails, with G100 examples citing a typical 5 second response and some legacy documentation allowing up to 60 seconds as a maximum. Commissioning should include an on-site functional test of this fail-safe behaviour, and larger connections may be subject to a DNO witness test before energisation. Installers should also lock down the settings so a homeowner or third party cannot alter the export cap without re-triggering commissioning.

Pro Tip: Photograph and log the commissioned MEL setting on-site. It saves time if a DNO asks for evidence during a later witness check.

DNO application and approval process: forms, timelines and common connection conditions

Getting a CLS approved involves a fairly standard paper trail, even though exact form names vary between network operators.

Confirm whether the project needs a G98 notification or a full G99 application based on the aggregate capacity against the 16A per-phase threshold.
Submit the relevant application alongside any CLS-specific forms your DNO requires, describing the hardware and control method chosen.
Wait for a response. Under Gov, DNOs typically respond within 45 days for low-voltage devices.
Complete installation and submit the commissioning form, generally within 28 days of energisation, as referenced in DNO and National Grid guidance.
Review the connection offer’s conditions carefully. These often set the maximum export figure, require witness testing, and may carry a time limit or associated charges.

Planning permission and permitted development rules sit alongside this process and are worth checking early, particularly for larger roof or ground-mounted arrays, as covered in our solar panel planning guidance.

Practical homeowner implications: clipping, batteries and export payments

Capping export at 3.68 kW sounds like a meaningful restriction, but the real-world effect on a typical domestic array is modest. Clipping losses are generally a small fraction of annual yield for 4 to 5 kWp systems, because peak generation on a sunny afternoon rarely coincides with the moments when a household’s own demand is at zero.

A battery absorbs surplus generation that would otherwise be clipped, increasing self-consumption rather than wasted export.
Smart load management, such as shifting an EV charge or immersion heater to coincide with generation peaks, reduces how often the export cap is actually reached.
Export metering still needs to reflect what is genuinely leaving the property for Smart Export Guarantee payments to be calculated correctly under the agreed limit.

Pairing export limitation with a right-sized battery, as discussed in our piece on how solar and battery storage cuts night-time import costs, is usually a more cost-effective response than oversizing a system and accepting heavier clipping.

Installer checklist: steps to design, install and certify a compliant G100 scheme

A CLS project runs more smoothly when the administrative work happens alongside the technical design, not after it.

Check likely network capacity early and engage the DNO before finalising system size, since this shapes whether export limitation will be needed at all.
Select hardware that is type-tested to EREC G100, whether that is an inverter with a built-in limit or an external controller and sensor package.
During commissioning, set the MEL and, where relevant, the MIL, then run fail-safe and operational tests to confirm the scheme behaves as designed.
Prepare for a possible DNO witness test and submit commissioning paperwork within the 28-day window referenced in DNO guidance.
Lock the settings against unauthorised change, hand over clear documentation to the customer, and flag whether a battery or load controls would meaningfully reduce clipping.

Pro Tip: Build the DNO’s 45-day response window into the client’s project timeline from day one. It avoids awkward conversations about delayed start dates.

Project administration across multiple sites is easier with dedicated tools such as construction software for solar installers, which can help track form submissions and commissioning deadlines across a busy schedule.

Differences between export limitations in various UK regions

The technical framework behind export limitation, EREC G100 together with G98 and G99, is a national set of engineering recommendations published by the Energy Networks Association, so the underlying rules do not change as you cross from one DNO area to another. What does vary is the specific application form, the local witness-testing arrangements and, in some cases, the typical response time within the 45-day window set out in gov.uk guidance.

SP Energy Networks, for example, publishes its own export limitation guidance explaining how it conditions larger connections on a G100 scheme to avoid reinforcement, and other DNOs across England, Scotland and Wales run broadly equivalent processes with their own paperwork. For readers in Dorset, Hampshire and Devon, this means the standards referenced throughout this guide apply consistently, but the exact form names and local turnaround times are worth confirming directly with the relevant DNO before submitting an application. Northern Ireland sits under a separate regulatory framework with its own network operator, so homeowners there should check requirements locally rather than assuming the same forms apply.

In practice, the regional variation that matters most to homeowners is less about the rules themselves and more about local network headroom. A rural feeder in Devon with limited existing capacity may need export limitation at a lower threshold than a well-reinforced urban connection elsewhere, even though both sites are governed by the same G100 standard.

Implications of export limitation on energy tariffs and potential financial impact

Export limitation affects your finances mainly through what it does to the volume of electricity you can sell back to a supplier under the Smart Export Guarantee, rather than through any separate fee for having a CLS fitted. Because clipping losses on a typical 4 to 5 kWp domestic system are generally a small fraction of annual yield, the effect on SEG income is usually modest rather than dramatic, particularly once a battery is absorbing surplus generation that would otherwise have been clipped.

There is no fixed market price for fitting a CLS. According to the EnergyStack knowledge base, costs depend on whether the limit is built into the inverter or requires an external controller and sensors, the complexity of the site, any DNO charges, and whether witness testing is required. A simple inverter-based limit on a single-phase home is typically the cheapest route, while a multi-inverter commercial site needing an external controller and DNO witness testing carries higher setup costs.

The financial trade-off homeowners actually face is usually between accepting a lower export cap now and reaching a larger system size sooner, versus waiting for network reinforcement to allow unrestricted export later. Given typical DNO response times and the modest real-world impact of clipping, accepting export limitation is often the financially sensible route for a standard domestic installation, especially when combined with a battery sized to capture what would otherwise be clipped.

Future developments or expected regulatory changes affecting export limitations in the UK

EREC G100 has already been through several amendments, with the current Issue 2 Amendment 2 reflecting ongoing refinement of fail-safe and reaction-time requirements as more homes and businesses install generation and storage. As the volume of small-scale solar and battery connections continues to rise, DNOs are leaning more heavily on export limitation as a tool to approve connections quickly rather than making every applicant wait for reinforcement, a pattern already visible in guidance from operators such as SP Energy Networks.

Flexible connection arrangements, where export limits can vary dynamically depending on real-time network conditions rather than sitting at a single fixed MEL, are an area network operators are developing further. For homeowners this could eventually mean export limits that loosen during periods of low local demand rather than staying fixed at a single number around the clock, though any such changes would still need to work within the G100 framework’s fail-safe principles.

Building regulations are also a moving part. Approved Document L already asks installers to document how renewable generation integrates with on-site storage, and that expectation is likely to tighten rather than loosen as more homes combine solar, batteries and EV charging on a single connection. Installers working on export-limited projects should expect the documentation burden around integration and sizing to grow rather than shrink over the next few years.

Common challenges or compliance issues faced by installers and homeowners

The most frequent cause of delay on export-limitation projects is not the technical design but the paperwork around it. Missing or late commissioning forms are a recurring issue, and because DNOs expect submission within a limited window after energisation, a gap in the administrative schedule can hold up final sign-off even when the hardware is working correctly.

A second common problem is confusing the two layers of approval. A device can be fully G98 or G99 compliant and still fail a CLS commissioning check if the export limitation hardware itself has not been separately tested and configured, since G100 manages the connection’s impact on the network rather than the generating device’s own conformity. Installers who treat these as a single sign-off sometimes find themselves re-submitting paperwork.

Homeowners occasionally run into trouble by adjusting inverter settings themselves after installation, not realising that altering the export limit without DNO agreement breaches the terms of the connection offer. Locking settings and explaining clearly why they matter at handover avoids most of these cases.

Finally, sizing decisions made without checking local network headroom first can lead to a connection offer with a lower export cap than the homeowner expected, which is why early engagement with the DNO, before equipment is ordered, remains the single most effective way to avoid surprises on either side.

A practical view from the field on export limitation

Export limitation is often the pragmatic choice rather than the second-best one. When a DNO quotes a long reinforcement wait for unrestricted export, fitting a CLS with a modest battery usually gets a larger system energised sooner and still captures most of the available yield.

Reinforcement makes more sense for commercial sites or future-proofed builds where the extra capacity will clearly be used within a few years. For a typical home, a certified installer working to G100 and G98/G99 standards keeps you compliant and protects your Smart Export Guarantee eligibility.

— Simon

How we can help with export limitation, solar and battery projects

We handle the whole export limitation process for homeowners and small businesses, from the initial site survey through to G100-compliant installation, commissioning and liaison with the local DNO. We size systems around your actual network capacity rather than guessing, and we build battery integration into the design where it genuinely reduces clipping rather than adding cost for its own sake.

If you are planning a solar or battery installation and want the export limitation paperwork handled properly from the start, our solar installations page is the place to request a survey and quote. For existing systems, our Solar & Battery Service & Maintenance Plan at £175 per year keeps your scheme’s settings and commissioning records in good order.

FAQ

What is an export limitation and how does it work?

An export limitation is a scheme that caps how much electricity a property can send back to the grid, measured at the connection point rather than at each individual device. It typically works through an inverter setting or an external controller that reduces output automatically if export approaches the agreed Maximum Export Limit.

What are the export laws and requirements in the UK?

UK export rules sit under EREC G100 for limitation schemes and G98 or G99 for generation connection approval, with installers required to notify or apply to their DNO before connecting. Commissioning paperwork generally needs submitting within 28 days of energisation, and DNOs typically respond to applications within a statutory period of about 45 days for low-voltage devices.

What does 5kW export limit mean?

A 5kW export limit means the installation is permitted to send up to 5 kW back to the network, a figure set by the DNO as a connection condition rather than a fixed national default. The common domestic default without a specific agreement is lower, at 3.68 kW on a single-phase supply, so a 5kW limit usually reflects a specific connection assessment or a three-phase supply.

What are the top 5 exports of the UK?

This question refers to the UK’s international trade exports, which is a different topic from electrical export limitation covered in this guide. We have not covered national trade statistics here, as our focus is on electrical grid export rules for homeowners and installers.