FIT vs SEG: What UK Solar Households Really Earn from Exports

The belief most new UK solar owners hold about exporting power

Ask a household that has just had panels installed how the money works and you hear the same story: the panels generate electricity, anything not used in the home is exported, the supplier pays for those exports, so the more you export the more you earn.

It is intuitive and wrong. Under the Smart Export Guarantee, the export rate is the smallest part of the return on UK rooftop solar. The bigger lever, by a wide margin, is the electricity you do not import in the first place. Optimising for export income while ignoring self-consumption leaves most of the value on the table.

FIT was generous, SEG is not, and why that is deliberate

FIT was a subsidy. It paid an above-market rate for every kilowatt hour generated plus a smaller rate for the share assumed exported, funded by a levy on every UK electricity bill. From FIT Year 17 (April 2023) the annual adjustment switched from RPI to CPI, which usually rises more slowly. SEG is not a subsidy: it is a requirement that suppliers buy your surplus at any price above zero. The government's intent is that solar should now pay back through cheaper hardware and self-consumption, with export as a top-up. SEG looking small next to FIT is not an accident, it is the design.

Why the "export everything you can" instinct is wrong

Under FIT, exporting more made sense because the rate was guaranteed and import prices were much lower (around 14p per kWh in 2015 versus 24.67p in April 2026). Under SEG the same instinct burns money: every kilowatt hour exported at 6p is one you will pay 24.67p to buy back that evening, an opportunity cost of about 18p per kWh.

Why typical FIT and SEG advice is out of date

A lot of online guidance still talks as if FIT were the active scheme: a generation tariff (paid for every kWh generated, exported or not), a deemed export rate (50% assumed exported, regardless of meter), and specific pence per kWh figures. None of these apply to a system installed after 31 March 2019.

Under SEG there is no generation tariff, no deemed export, no government-set rate. You are paid only for the exact kilowatt hours your half-hourly smart meter records flowing to the grid, at whatever rate the supplier publishes. That changes every recommendation that flows from it: system sizing, battery choice, import supplier, even when in the day you run appliances.

How export payments actually work today

SEG runs on three pillars: a per-supplier tariff, a half-hourly smart meter, and a minimum installation standard. You qualify if your low-carbon generation (solar PV, wind, micro-CHP, hydro or anaerobic digestion) sits below 5 megawatts, your system is MCS-certified (Microgeneration Certification Scheme, the UK quality standard for small-scale renewables) or equivalent, and you have an export-capable smart meter.

SEG rates: who sets them and why they vary so much

Ofgem requires every supplier with 150,000 or more domestic customers to offer at least one SEG tariff above zero pence per kWh. Smaller suppliers may also offer one. Beyond that, suppliers compete (or fail to) on price, contract length, and whether the rate is fixed or varies half-hour by half-hour with wholesale conditions.

In 2024 and 2025 published rates have ranged from around 1.5p per kWh on "any customer" tariffs to about 15p on tied tariffs that require you to buy your import from the same supplier. Most sit between 3p and 8p per kWh. Treat any single figure as illustrative until you check the supplier's own SEG page; 15p tariffs in particular have been raised and withdrawn several times since 2022.

The role of half-hourly smart metering

SEG settlement runs on half-hourly data, so you need a SMETS2 (or properly upgraded SMETS1) smart meter operating in smart mode with export readings transmitted automatically. If your meter is not in smart mode you cannot claim, even with MCS-certified panels.

Half-hourly data also unlocks something FIT never offered: time-varying export rates that pay more when the grid wants electricity and less when solar is already plentiful. For a home without a battery, that pattern is unhelpful because most of your export happens when prices are lowest. With a battery, time-varying tariffs become genuinely interesting.

Where UK solar households leave money on the table

Two recurring mistakes account for most of the missed income on a UK domestic solar install, both flowing from confusion between FIT logic and SEG logic.

Sticking with the SEG tariff bundled by their import supplier

Ofgem does not require you to take your SEG tariff from your import supplier. You can pick any SEG provider and keep your import elsewhere; switching the SEG tariff alone does not affect your import contract. Tied SEG tariffs from larger suppliers often pay more (precisely because they require you to bundle), but not always, and some standalone offers beat the default tied rate.

A household that accepts the first rate offered without comparing often locks in 1.5p to 3p per kWh when the same export pattern would have earned 5p to 8p elsewhere. On 1,500 kWh of annual export, that gap is worth around £50 to £100 a year.

Ignoring self-consumption (the real saver)

Self-consumption is the share of your solar generation you use inside the home. Without a battery, typical UK self-consumption is 25% to 40% of generation. With a home battery, it rises to roughly 60% to 80% because solar produced during the day is stored for the evening peak.

Every self-consumed kilowatt hour is worth the full 24.67p Ofgem cap (April to June 2026), against only 5p to 8p for an exported one. Self-consumption is three to five times more valuable than the export sale. Run the dishwasher, washing machine and EV charger overnight while exporting solar at midday and you are effectively buying back your own electricity at a 17p to 19p per kWh loss. The widget below quantifies that difference.

Insider truth: self-consumption is worth more than any SEG rate

A typical south-facing 4 kWp rooftop system generates around 3,400 to 4,000 kWh per year. Without a battery the home uses about 30% internally (around 1,100 kWh) and exports the rest (around 2,500 kWh). At 24.67p per kWh import, the self-consumed share saves roughly £272 a year; at a healthy 6p SEG rate, export earns about £150. Self-consumption does 64% of the work despite representing less than a third of the generation.

Add a battery and the gap widens. Self-consumption rises to roughly 70%, avoided imports climb to about £634 a year, and SEG income falls to around £72 because there is little left to export. Total benefit jumps from about £422 to about £706 a year, even though export has more than halved. The lesson is consistent: optimise to keep the electricity in the house, not to push it out.

What you should actually do

The right move depends on whether your installation predates the FIT closure or whether you are installing new panels under SEG. The two situations need different playbooks.

Existing FIT holders: protect your scheme

If you were accredited before 1 April 2019, your generation and export tariffs continue for the rest of your eligibility period (usually 20 years). Switching your import supplier is fine. Switching the FIT provider itself is allowed under Ofgem rules but check the new provider's terms first, since some contracts pay slightly above the statutory rate. Keep your MCS certificate, original FIT statement and meter records. Talk to your FIT provider before upgrading the inverter, replacing panels or extending the system, because some changes can void eligibility if not declared. You cannot stack a SEG tariff on top of the FIT export tariff for the same generation.

New solar installs: pick your SEG tariff separately

For a post-April 2019 system: choose an MCS-certified installer, commission the system, make sure your smart meter is in smart mode and export-capable, then apply for a SEG tariff. SEG and import are separate contracts; do not assume the easy bundled option is the best rate.

Compare at least three SEG tariffs from larger obligated suppliers and any smaller specialist offers. Look at the headline rate, contract length, fixed vs half-hourly, and whether you must bundle import to qualify. If you are still in the design phase, size the system to your roof rather than to your demand: panels are cheap and exported solar at 6p still beats not generating it. The decision that matters more is whether to add a battery.

Conclusion: solar pays back through what you do not import, not what you export

FIT was a subsidy for a different decade; SEG is a market mechanism for the world we are in now, with panel prices down more than 80% since 2010. Comparing the two by export rate alone misses the point. Run the widget, set your real numbers, and look at the split between import savings and SEG income. In almost every UK scenario, avoided import is the larger figure. Sequence dishwashers and EV charging into daylight hours, consider a battery, size the system generously, and pick a decent SEG rate by all means, but build your return on the units that never leave the house.