Smart Export Guarantee
Mandatory scheme requiring large electricity suppliers to pay for surplus solar generation exported to the grid.
Typical 2026 SEG tariffs: 4p–15p per kWh exported. Best rates: Octopus Outgoing Agile (variable, half-hourly tracked), Octopus Outgoing Fixed, OVO SEG. Worst rates: legacy supplier minimum-compliance tariffs at 3p–5p.
Permanent scheme. Tariff rates change frequently — annual review of supplier offers is sensible.
In detail
The Smart Export Guarantee replaced the Feed-in Tariff in 2020 and is now the standard mechanism by which UK businesses earn revenue from surplus solar generation. The scheme is structurally simple — large suppliers must offer at least one tariff for export — but tariff levels vary by an order of magnitude between best and worst suppliers. As of 2026, the best SEG rates sit around 12p–15p per kWh, with Octopus Energy's Outgoing Agile tariff (variable, tracking the half-hourly wholesale market) often the highest annualised return for systems with daytime-skewed generation. The worst SEG rates sit at the regulatory minimum, around 3p–5p, offered by suppliers who comply with the obligation but don't compete for export business. For commercial systems sized appropriately to demand (i.e. 70%–90% self-consumption), SEG income is a useful but secondary economic line — typically 5%–10% of total system value over 25 years. For oversized systems generating significant surplus, the calculation shifts: at high export volumes, a Power Purchase Agreement with a corporate offtaker often pays materially more than SEG, sometimes 50%–100% better. We model both for any system where export is expected to exceed 30% of generation.
Who qualifies
Owners of solar systems up to 5MW capacity, with MCS-certified installations below 50kW. Above 50kW, MCS is not strictly required for SEG eligibility but most suppliers expect equivalent quality assurance. Export must be metered with a half-hourly export meter.
What it does
Obliges electricity suppliers above a threshold (currently those with 150,000+ domestic customers) to offer at least one tariff for excess solar generation exported to the grid. Tariff rates and structures are set by each supplier.
Worked example
On a 250kWp commercial system with 80% self-consumption: 49MWh per year exported. At 8p/kWh average SEG: £3,920 per year. At 12p/kWh (best 2026 rates): £5,880 per year. Lifetime export income (25 years, modest tariff growth): £100k–£175k. Useful but secondary to self-consumption savings, which are typically £35k–£50k per year on the same system.
Tax treatment / process
- Install MCS-certified system (or equivalent for >50kW) with half-hourly export meter
- Apply to chosen SEG supplier with MCS certificate, MPAN, and export meter details
- Sign export agreement specifying tariff and review terms
- Receive payments quarterly or monthly based on metered export volumes
Pitfalls to watch
- SEG rates from your import supplier are usually NOT the best rates — switching the export contract separately is often worth it
- Some suppliers tie SEG to import tariff — restricts your ability to switch import supplier
- Half-hourly export metering required — adds a one-off cost
- Tariff often resets after 12–24 months — long-term certainty is limited
- PPAs can pay materially more than SEG for larger systems — worth comparing for >100kW systems
Best paired with these finance structures
Run the numbers on your project
We build the after-tax model with the right reliefs applied — no missed deductions, no double-counted benefits.
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