Smart Export Guarantee (SEG) for Commercial Solar Carports
UK commercial solar carports typically export 15-30% of annual generation back to grid. SEG tariffs determine how valuable that export is. Here's the 2026 landscape.
What SEG is
Smart Export Guarantee — introduced January 2020 to replace the closed Feed-in Tariff (FIT) — requires electricity suppliers with over 150,000 domestic customers to offer a SEG tariff for surplus electricity exported from sub-5MW generation. Suppliers set their own tariffs; rates vary widely.
Current SEG rates
Octopus Energy Outgoing Fixed: 15.0p/kWh (best fixed). Octopus Outgoing Agile: variable, tracking wholesale prices (often 4-25p/kWh). EDF Energy Export+: 5.5p/kWh fixed. OVO Energy SEG: 4.0p/kWh fixed. British Gas Export and Earn: 4.5p/kWh fixed. Smaller suppliers (Good Energy, Octopus, So Energy) routinely offer better rates than Big 6.
Eligibility
Solar PV under 5 MW (which covers all commercial carports in the UK). An MCS certificate where the system is 50 kW or under. Export meter installed (smart meter or dedicated export meter). DNO G99 connection in place. SEG application made to chosen supplier — typically a 1-2 week process.
Export volume in practice
UK commercial carports: typical 75-85% self-consumption; 15-25% export. A 300 kWp carport generating 255,000 kWh/yr exports ~38,000-64,000 kWh/yr. At 12p/kWh SEG (Octopus Outgoing Fixed, cut from 15p on 1 March 2026), that is £4,560-£7,680/yr export revenue.
How to maximise SEG revenue
(1) Choose the highest-paying SEG supplier — Octopus Outgoing Fixed pays 12p/kWh as of March 2026 (cut from 15p on 1 March 2026); (2) Use Octopus Outgoing Agile for sites that can shift load to off-peak (export at premium times); (3) Add battery storage to time-shift export to peak SEG hours (4-7pm typically pays best); (4) Switch supplier annually if SEG rates change; (5) Consider corporate PPA off-takers — some pay 10-13p/kWh fixed for direct PPA, vs SEG variable.
SEG vs PPA: which is better?
SEG (Octopus Outgoing Fixed, 12p/kWh as of March 2026): simple, no contract commitment, can switch supplier. Corporate PPA: 10-14p/kWh typical, locked-in for 5-15 years, requires sleeving via Octopus or REGO certificates. Most commercial carports take SEG for simplicity unless export volume exceeds 200,000 kWh/yr (where PPA economics improve).
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