Solar Calculator UK 2026

Solar in the UK: how the Smart Export Guarantee works

Solar makes good sense in the UK despite its cloudy reputation — modern panels generate usefully even in diffuse light, and high electricity prices mean the power you offset is valuable. There's no upfront subsidy any more (the Feed-in Tariff closed to new applicants in 2019), but you earn from exported surplus through the Smart Export Guarantee (SEG), and you save most by using your own solar. This calculator estimates both, using SEG rates re-verified for 2026 and treating self-consumption and export separately, as accurate UK solar maths requires.

SEG rates change and are presented here as dated references; confirm current tariffs before purchasing.

What the SEG is — and isn't

The Smart Export Guarantee requires larger energy suppliers to pay you for electricity you export to the grid. It replaced the more generous Feed-in Tariff, and crucially it only pays for exported units — there's no payment for what you generate and use yourself. Rates vary widely by supplier: the regulatory minimum sits around 4p/kWh, while the best flat rates are higher — for example, Octopus's popular Outgoing Fixed tariff (cut from 15p to 12p in March 2026), Good Energy around 15p, and bundled tariffs from E.ON Next and British Gas around 15–16.5p for their own import customers. Battery owners on time-of-use export tariffs (Octopus Flux and Agile) can earn 25–32p during peak windows. You'll need an MCS-certified installation and a smart meter to claim SEG.

Self-consumption beats export — by a lot

Here's the key to UK solar economics: a unit of solar you use yourself is worth far more than one you export. Using your own generation avoids buying grid electricity at the import rate (around 25p/kWh), whereas exporting earns you the SEG rate (often 4–15p). So self-consumed solar is worth roughly two to five times exported solar. That's why the falling export rates — Octopus's cut from 15p to 12p reflects a wider trend as UK solar capacity grows — matter less than people fear: the bulk of your savings comes from using your own power, not selling it. Shifting flexible loads (washing, dishwasher, hot water, EV charging) into daylight hours, or adding a battery, raises self-consumption and is the single most effective way to improve returns.

The 0% VAT window and other rules

Residential solar and battery installations currently carry 0% VAT in Great Britain until 31 March 2027, after which the rate is scheduled to return to 5% (not the standard 20%). That's a genuine, dated saving worth factoring into timing — though it's a reason to plan sensibly, not to rush into a poor decision. You'll also need an MCS-certified installer to qualify for SEG and for the VAT relief, and a smart meter to measure exports. These are practical requirements rather than obstacles, but worth knowing before you commit.

Frequently asked questions

For most homes, yes. High electricity prices mean the power you offset is valuable, and panels generate usefully even in the UK's diffuse light. The savings come mainly from self-consumption rather than export, so using your own solar (or storing it) is what makes the case strong.

Among flat rates, Octopus Outgoing Fixed (12p, reduced from 15p in March 2026), Good Energy (~15p) and bundled tariffs from E.ON Next and British Gas (~15–16.5p for their import customers) are competitive. Battery owners on time-of-use tariffs can earn 25–32p in peak windows. The standard SEG minimum is around 4p.

A battery raises self-consumption — letting you use more of your own solar instead of exporting it cheaply — and enables high-rate time-of-use export tariffs. With export rates falling, storing and using your own power is increasingly where the value lies, though a battery's cost still has to be weighed against the savings it adds.

No — the FiT closed to new applicants in 2019. New solar homes earn through the Smart Export Guarantee instead, which pays only for exported electricity. There's no upfront generation subsidy now, so the case rests on bill savings plus SEG export income.

About 8 kWh a day or 2,897 kWh a year on average, from about 3.1 a day in December to 11.6 a day in June, according to PVGIS data for panels at the best fixed angle. Shading, dust and orientation change the result.