Smart Export Guarantee tariffs Q1 2026: a cross-supplier comparison

Smart Export Guarantee tariffs are diverging meaningfully across UK suppliers. The Q1 2026 cross-supplier table shows where the value is — and what to assume for export revenue in a 25-year cash-flow model.

The two main tariff structures

SEG tariffs come in two forms. Fixed-price SEG tariffs pay a flat pence-per-kWh for all exported solar, set at point of contract and adjusted periodically. Most major UK suppliers offer fixed-price SEG between 5p and 12p depending on supplier and contract.

Market-linked SEG (sometimes called flexible or wholesale-linked) pays a pence-per-kWh that varies with wholesale electricity prices, typically a percentage of day-ahead wholesale or a wholesale-tracker formula. Better when wholesale is high, worse when it's low. Currently delivering 6–11p effective average for export-heavy projects.

Cross-supplier table (Q1 2026)

Note: Octopus Outgoing Lite (15p) is the standout fixed-price tariff but capped at 5,000 kWh/year of export — beyond that customers move to Outgoing Fixed (8.5p) or Agile Outgoing (market-linked). For commercial sites exporting more than 5 MWh/year, the effective Octopus rate works out at ~8.5–9p depending on export profile.

What the variation tells us

SEG was structured by Ofgem as a market-driven scheme — suppliers must offer a tariff but can set the rate. The result has been wide divergence: incumbents (EDF, E.ON, British Gas, Scottish Power) cluster around 5.5–6.5p, reflecting cautious pricing of export risk. Challengers and renewable-positioned suppliers (Octopus, OVO, Good Energy, SO Energy) compete more aggressively at 7.5–9p effective for typical commercial volumes.

The divergence is meaningful for project economics. On a 250 kWp commercial system with ~8% annual export (20 MWh/year), an extra 3p/kWh of SEG tariff is £600/year — small in absolute terms but worth 0.3 percentage points of project IRR over 25 years. Worth optimising for, but not the deciding factor in project structure.

Eligibility quirks worth noting

Existing customer requirement. Five of the eight major suppliers require the SEG customer to also hold an electricity import contract with the same supplier. This restricts free choice and effectively bundles SEG with import procurement. For multi-supplier portfolios, this is a real constraint on optimising export tariff.

MCS certification. SEG eligibility requires MCS certification of the installation for systems below 50 kWp, or G98/G99 commissioning evidence for larger systems. Installer competence on the documentation matters — projects that fail certification can spend months chasing eligibility post-commissioning.

Contract length and tariff resets. Most fixed-price SEG tariffs are 12-month contracts that revert to a standard variable rate at end-of-term. Active management is required to capture re-pricing — set a calendar reminder for the 11th month of every contract.

Implications for the 25-year model

For commercial solar finance modelling, we typically use a blended SEG assumption of 7p/kWh real terms over 25 years. This is below the best-available rate today (Octopus 9p effective for commercial volumes) but above the bottom-quartile (5.5p incumbent). The discount reflects: (1) supplier-switching friction in commercial procurement; (2) policy risk (SEG could be reformed or replaced); (3) wholesale price uncertainty (market-linked tariffs offer upside but also downside); (4) realistic export percentage (8–12% on well-sized commercial systems, lower than headline marketing materials).

Sensitivity at 5p downside and 10p upside captures the practical range. On a typical 250 kWp project with 8% export, the difference between 5p and 10p SEG over 25 years is approximately £35,000 in cumulative cash. Material but not transformative — the case for solar still stands at any reasonable SEG assumption.

When to prioritise SEG optimisation

For most commercial solar projects sized for self-consumption (export below 15% of generation), SEG tariff selection is a second-order decision. Get the import-side electricity supplier right first. SEG matters more for projects with high export percentages — agricultural ground-mount, oversized landlord-funded portfolio installations, summer-shutdown education sites — where 20%+ of generation is exported and the tariff differential moves project IRR by a percentage point or more. On those projects, SEG optimisation is worth the procurement effort.