Solar export and SEG

SEG scope and process

SEG is the Great Britain scheme under which participating electricity suppliers offer payment for eligible small-scale low-carbon generation exported to the grid.

For a home solar installation, the practical chain is:

1. the PV system is designed and connected through the correct DNO route
2. installation and installer certification evidence is issued
3. suitable export metering is available
4. an export MPAN is created and enrolled
5. a SEG licensee accepts the application
6. export is paid under the supplier’s contract and actual meter readings

The steps can overlap, but none should be treated as proof that all the later stages are complete.

SEG does not apply in Northern Ireland. The Northern Ireland route is covered separately below.

DNO connection and export payment

The DNO assesses the connection of the generation equipment. In Great Britain, a qualifying G98 installation can be connected and notified after commissioning. A G99 installation normally needs the appropriate application and acceptance before connection.

The DNO record concerns the network connection and installed generation. It is not an export-payment contract.

Keep:

• submitted equipment and capacity
• G98 notification or G99 application
• DNO acknowledgement or offer
• final export-limit setting where applicable
• commissioning date

A supplier may request DNO evidence during an export application. That request supports the supplier’s eligibility and enrolment checks. It should not be described as though DNO notification itself activates SEG.

The home solar installation guide explains the G98 and G99 boundaries and the installation records to retain.

Installation certification

Ofgem’s domestic-scale certification rules distinguish the installation from the installer. For solar PV, wind and micro-CHP up to 50 kW, suitable installation and installer certification are required for the licensee’s statutory SEG obligation.

MCS is the normal route for domestic solar. Ofgem also permits an equivalent accredited scheme that meets the specified certification basis. A supplier is not obliged to accept an application that cannot demonstrate suitable certification, although it may choose to make another export offer.

Provide the exact issued certificate rather than an installer’s membership logo or quotation reference. The certificate identifies the completed installation.

Certification does not replace the electrical certificate, Building Regulations evidence, DNO record or proof that the applicant is entitled to the export. Keep each separately.

Export meter requirements

The export meter must be capable of measuring export in half-hourly periods and have an export MPAN.

The meter measures electricity leaving the property at the grid connection. It does not measure total PV generation. Electricity used in the home before reaching the meter is self-consumed and does not appear as export.

These quantities have different boundaries:

• PV generation is total AC energy produced by the solar system
• household consumption is energy used by loads in the home
• grid import is electricity entering from the network
• grid export is electricity leaving for the network

An inverter portal can show generation. A CT (current transformer) or energy meter may derive household use. The settlement meter records import and export for the supplier. The figures should not be expected to match because they measure different paths and may use different intervals.

Ofgem’s statutory guidance requires half-hourly measurement capability. It does not make remote reading a universal requirement for every SEG arrangement. Where a meter is not remotely read, the generator and licensee need an agreed actual-reading process. Individual tariffs can impose additional smart-meter conditions.

Import and export MPANs

Import and export use distinct MPANs even when one physical smart meter records both directions.

An import MPAN on a bill does not prove that the export MPAN has been created or enrolled. The export process can involve:

• installation and DNO evidence reaching the relevant parties
• the DNO creating the export MPAN
• the SEG supplier enrolling it
• meter data becoming available
• the tariff contract going live

Supplier processes differ. Some suppliers request an export MPAN from the DNO as part of the application. Others may require an existing identifier or use a different sequence. Follow the current instructions of the chosen SEG licensee.

Do not rely on a universal creation time or payment backdate. Ofgem does not set one general activation period or supplier payment frequency for every contract.

Choosing a SEG supplier

The SEG supplier can be different from the import supplier and gas supplier. This allows a household to compare export terms separately, although some commercial tariffs offer different export rates to their import customers.

Check:

• export rate and whether it is fixed, variable or time-based
• eligibility and installation-size limits
• import-tariff dependency
• meter and communications requirements
• battery and grid-charged export treatment
• contract term and rate-change provisions
• payment frequency
• reading process
• leaving or switching terms
• treatment when the property changes owner

Ofgem publishes a current list of SEG licensees. The statutory scheme requires a positive rate, but it does not prescribe one market price.

Compare expected annual export under the household’s own profile. A higher rate tied to a more expensive import tariff may not reduce the whole electricity bill. Treat import, standing charge and export together where the products are linked.

Application evidence

Check the selected supplier’s current application list. Common records include:

• MCS or accredited-equivalent certificate
• DNO acknowledgement
• export meter details
• electricity account and import MPAN
• proof of identity and address
• bank details
• proof of ownership or entitlement to receive export payment
• commissioning date
• FIT status where relevant

Only the core certification, meter and export-MPAN requirements should be presented as universal SEG scheme tests. Other documents can be required by the supplier to administer the application, verify the applicant or enrol the meter.

Use the same installation address and equipment details across MCS, DNO and supplier records. Resolve discrepancies rather than submitting several versions.

FIT installations

FIT has separate generation and export elements.

An eligible legacy installation can continue receiving FIT generation payments and receive SEG for metered export. It cannot receive FIT export payment and SEG for the same installation capacity and exported electricity.

The generator must opt out of FIT export before receiving SEG where required by the scheme process. Do not cancel the FIT generation registration.

Keep:

• FIT installation identity and capacity
• FIT licensee correspondence
• generation-meter serial and readings
• export opt-out confirmation
• SEG acceptance

Adding a battery, replacing an inverter or changing the array can affect the accuracy of generation and export measurement or the accredited installation record. Tell the FIT licensee before work where the current guidance requires it and keep the revised schematic.

Batteries and mixed-source export

A battery can export energy that originally came from the grid as well as energy from eligible solar generation. Ofgem’s SEG guidance treats this as mixed-source export.

Where the export meter also measures an ineligible source, the licensee is not obliged to pay for all of it under SEG. It may:

• require additional metering
• estimate or apportion the eligible share
• pay all export under its commercial terms
• exclude the mixed export

The exact treatment varies between suppliers and tariffs. Do not assume that a battery is eligible because the site already has an export MPAN.

Check whether the battery schedule, export mode and tariff terms allow grid charging followed by export. A permitted technical mode is not necessarily permitted under the energy contract.

If the property has a legacy FIT installation, the battery’s position relative to the generation meter also matters. The schematic should show whether stored or grid energy can cross that meter.

Export limitation

A G100 export limit restricts net export at the connection point. It can allow more generation or storage capacity to be installed behind a lower agreed export ceiling.

The export limit affects how much energy can reach the SEG meter at a time. It does not guarantee a particular annual export and does not change the installation’s Registered Capacity for G98 or G99 assessment.

Keep the commissioned export setting, control scheme and DNO acceptance. If the battery, inverter or CT arrangement changes, check whether the approved limitation scheme needs review.

Northern Ireland

SEG applies in England, Scotland and Wales. Northern Ireland has its own electricity market, network connection standards and export arrangements.

Northern Ireland microgenerators sell metered export directly to a supplier or through an agent under the applicable arrangements. Check the current Utility Regulator and supplier information rather than applying the SEG process or Great Britain supplier list.

NIE Networks also uses G98/NI and G99/NI rather than the Great Britain documents. Keep the network and payment routes separate in the same way as a Great Britain installation.

Tracking the application

Use a simple status record:

If progress stops, identify the missing stage before contacting several organisations. The installer owns installation evidence, the DNO owns the network record and MPAN creation within its process and the SEG supplier owns enrolment and the payment contract.

Save screenshots or emails that show the date and identifier of each submission. An inverter’s export graph does not prove that settlement data has reached the supplier.

Moving home or changing the system

The right to receive export payment and the tariff contract need to be addressed when a property changes owner. Keep the MCS certificate, DNO record, export MPAN, meter details, FIT information and system schematic in the property handover pack.

Contact the current supplier about its transfer or closure process. Do not assume the import account, SEG account and FIT registration will all move under one instruction.

Before adding panels, replacing the inverter or installing a battery, check the DNO, MCS, FIT and SEG consequences. A physical system change can alter Registered Capacity, metering or tariff eligibility even where the export limit remains the same.