Export income

British Gas cut its Smart Export Guarantee rate for systems above 15kW from 15.1p to 8p per kWh, a change aimed at larger commercial installs that still shows why every SEG rate is a variable business decision, not a fixed promise

From 6 July 2026, British Gas pays 12p per kWh for exported solar up to 15kW and just 8p above that threshold, a cut that turns 100,000 kWh of annual export from roughly £15,100 into about £8,000, hitting manufacturing sites, warehouses, farms, schools and other larger operations hardest.

29 July 2026 · Source: Flame Energy

The mechanics of this cut matter more than the headline percentage. British Gas has not simply lowered its rate across the board, it has introduced a size threshold: systems up to 15kW keep a 12p rate, while anything larger drops to 8p. That is a deliberate split between the domestic-scale market, where a typical 4kWp Kent household installation sits nowhere near the threshold, and the larger commercial and agricultural systems that do. If you are a homeowner reading this expecting your own export income to be affected, it likely isn't; if you run a business with a larger rooftop or ground-mount array, it very much is.

The £7,100-a-year swing on 100,000 kWh of export is the number that makes this concrete rather than abstract. That is the difference between a solar investment case that still pencils out comfortably and one that needs re-running, for exactly the size of installation, schools, farms, warehouses, that this site's commercial customers are most likely to be considering. A rate cut of this size after the system is already installed and financed is the real-world version of the export-income risk that gets glossed over in a simple payback calculation done before signing anything.

The underlying cause is structural rather than a one-off British Gas decision. Most SEG tariffs are variable by design, which is precisely why the flat, no-conditions comparison this site covered in the Octopus Outgoing cut story earlier this year keeps recurring across different suppliers rather than being an isolated event. Suppliers can and do revisit these rates as market conditions change, and a rate that looks competitive at the point of signing a contract carries no guarantee it stays that way for the life of the installation.

For anyone sizing a commercial-scale system now, the practical takeaway is to model the payback case on a conservative, not headline, export rate, and to treat fixed-term Power Purchase Agreements as a genuine alternative worth comparing rather than a fallback, since a PPA's certainty has real value against a variable SEG tariff that can be revised with little warning. Watch whether other major suppliers follow British Gas with their own size-tiered rate structures, since a tiered market becomes the new normal faster once one major supplier has shown it's viable.

Read the original: Flame Energy. Commentary is Sandwich Solar's own editorial view; the original reporting is credited to its publisher.

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