Planning map, not approval advice: Requirements depend on location, phase, aggregate inverter capacity, equipment type and operating mode. Use current ENA and DNO documents before committing to equipment.
Who does what?
- DNO: operates the local distribution network and processes connection notifications/applications.
- ENA: publishes industry engineering recommendations and maintains equipment/type-test resources.
- Installer/designer: establishes the correct route, protection and evidence for the actual system.
- Supplier/SEG licensee: sets export payment eligibility and tariff terms; this is separate from technical connection permission.
G98 and G99
ENA states that energy storage devices connect under Engineering Recommendations G98 and G99. Broadly, G98 covers small-scale generating equipment that meets its limits and type-test conditions, while G99 covers generating equipment outside the G98 route and normally requires application before connection. Battery inverters are generating equipment when they can supply the installation/network.
Do not assume two individually small inverters remain a G98 arrangement: aggregate capacity and the combined solar-plus-storage configuration matter.
G100 export limitation
G100 covers customer export-limitation schemes. An export limitation can constrain power at the connection point where the DNO accepts the scheme; it is not permission to ignore G98/G99, and a software setting alone is not necessarily a compliant export-limitation scheme.
Battery-only and no-export systems
A battery charged only from the grid can later discharge through a grid-connected inverter. The DNO question therefore remains even without PV. Backup-only/off-grid modes need a defined changeover and must not energise the public network during an outage.
SEG and MCS
Ofgem describes the Smart Export Guarantee as a route for eligible small-scale low-carbon generators to receive export payments. Technical connection, metering and the chosen SEG licensee’s evidence rules are separate checks. MCS certification is commonly relevant to consumer protection and export evidence, but it does not replace DNO requirements. Battery-only grid-charged export eligibility and tariff treatment must be confirmed with the specific supplier.
A safe planning sequence
- Identify the DNO for the property.
- List every grid-connected inverter and its maximum output.
- Check ENA type-test evidence and aggregate configuration.
- Establish G98 notification, G99 application or fast-track route with the DNO.
- Document any G100 export limitation and fail-safe behaviour.
- Only then treat export income as a supported economic input.
Keep technical permission separate from payback.
Model import and export using only terms you can actually obtain.