Are solar panels worth it in 2026? The honest payback maths

Every solar sales page promises a 6–7 year payback. Run the numbers on real irradiance data and real 2026 prices and the honest answer is 8 to 17 years — and where you sit inside that range depends less on the panels than on three things nobody puts in the brochure: where you live, what you're paid for exports, and how much of your own generation you actually use.

What a system costs in 2026

A typical 4 kWp installed system runs £6,000–£7,000 — about £1,625–£1,800 per kWp, with small 3 kW jobs nearer the top of the range and MCS putting the England average around £1,565/kWp (April 2026, checked Aug 2026). Domestic solar carries 0% VAT until 2027, which is already baked into those quotes, not a discount to negotiate. A battery adds £2,000–£4,500 and changes the maths in both directions: more self-use, more capital to pay back.

What your roof will actually generate

We compute this from PVGIS — the EU's satellite irradiance model, built on nearly two decades of measured radiation data. For a decent south-facing roof at 35°, the UK band is roughly 850–1,050 kWh per kWp per year: Exeter tops the table at 1,052, Cardiff 1,042 and London 1,019, while Manchester (886) and Glasgow (853) sit roughly a fifth lower. That gap alone moves payback by years — a national average is meaningless, which is why our checker looks up your actual postcode. East/west roofs lose a further ~15–20%; shaded or north-facing roofs are where the case genuinely dies.

The 3p-vs-25p spread: your export rate matters more than your panels

Here's the underreported story. Every kWh you don't use goes to the grid under the Smart Export Guarantee — and across the 13 tariffs we checked in August 2026, rates span 3p to 25p per kWh. An eight-fold difference, for identical electricity, decided entirely by paperwork.

The market splits into three tiers. Open to anyone: 3–6p — British Gas and EDF pay 3p, OVO 4p, ScottishPower 6p. This is the default trap: install, do nothing, get 3p. Their import customer: 12–13p — switch your electricity supply to EDF (13p), Octopus, British Gas or OVO (12p) and your export rate quadruples. They installed it: 16.5–25p — Good Energy's 25p (solar plus battery, their installers only), OVO's 20p and EDF's 18p are real but locked to buying the system through them, so weigh the whole quote, not the headline rate. Every tier needs an MCS certificate and a smart meter, and rates churn — Octopus cut its main export rate from 15p to 12p in March 2026. The practical rule: never accept a 3p default; 12p is available to almost everyone willing to switch supplier, and on a typical system that single decision is worth more per year than an extra panel.

The payback maths, honestly

Put it together with our engine's own outputs: a 4 kWp system in Manchester (~£6,500 installed) returns £377–£676 a year depending on self-use and export rate — payback 9.6–17.2 years. The same system in Exeter pays back in 8.0–14.4 years. Panels typically carry 25-year performance warranties, so even the slow end eventually pays — but "worth it" depends on you being there to collect, which is why the who-shouldn't list below matters more than the averages.

The £7,500 heat pump grant (and the honest catch)

The Boiler Upgrade Scheme pays £7,500 towards an air or ground source heat pump in England and Wales — verified on gov.uk, August 2026 — with a £1,500 uplift (£9,000 total) until March 2027 for homes heated by oil or LPG with no mains gas. Biomass gets £5,000, air-to-air £2,500. You must own the property and be replacing a fossil-fuel system; the installer applies, not you. The catch nobody advertises: at current capped rates (26p electricity, 7.3p gas) electricity costs 3.6× gas, so a heat pump running at SCOP 3 roughly breaks even on running costs — a well-installed SCOP 4 system saves around £275 a year once the gas standing charge goes. With typical installs at £8,000–£15,000 before grant, the grant is the whole case. Take it while it exists; don't expect the bills alone to justify it.

Who shouldn't buy solar

Skip it if: your roof is shaded or north-facing (no export rate rescues missing sunlight); you're likely to move within ~8 years — payback rarely beats your tenure, and panels add less to a sale price than they cost; or you're a very low user out all day with no battery, because self-use at ~26p is where most of the value lives and exporting everything at even 12p roughly doubles the payback. And get three quotes — the spread between installers on identical kit is routinely four figures.

Figures from PVGIS satellite data, gov.uk and supplier SEG pages, checked August 2026 — modelled ranges, not quotes or guarantees; rates and grants change. Factual information, not financial advice. Installer links on our tools may be affiliate links; the best option always ranks first even when it pays us less, or nothing.