Four ways to have solar
A typical 4–4.5 kWp system costs about £6,400–£7,600 installed (DESNZ median, Energy Saving Trust). Since 27 August 2026 there is also a legal plug-in route for homes without a roof to call their own.
Needs land; can be angled and sized freely. Trenching and frames add cost. Up to 9 m² without planning permission in England.
Money 0% VAT when installed by the supplier
Ground mount →Try the payback dials
We start from a typical home — twelve panels on a south-facing roof, 2,700 kWh a year, someone in some days. Change what you know and watch the payback move. The full calculator asks ten questions and gives you your own range.
Main roof faces
Someone usually home
Tariff
UK average yield, 950 kWh per kWp, until you add a postcode · typical pitch, no shading assumed.
4,400–5,400 kWh a year from 12 panels (5.2 kWp), covering about 34% of 2,700 kWh.
Estimates, always a range. Costs are DESNZ medians for MCS installations (2025/26) and Energy Saving Trust figures, checked 24 September 2026; batteries are extra. Every number and its source is in the results page’s “How this estimate works”.
Want it for your roof? The calculator keeps these picks and asks the rest — tenure, pitch, shading, what you have or plan.
What decides your payback
The Energy Saving Trust's 9–12 years assumes an average roof and an export payment. Your roof, your daytime use and your tariff decide where in that range you land — or outside it.
South makes the most per panel; east–west about 80%; north 45–76% by pitch. Shade can cut output sharply.
Read the answer →02Without a battery a typical home uses only 15–39% of its solar. Size for what you use in the day, not for the roof.
Read the answer →03A 4–5 kWh battery lifts self-use from about 25% to 63%; a cheap overnight rate makes it earn in winter too.
Read the answer →04Basic SEG pays 3–6p, import customers about 12p. Above 3.68 kW the network operator can cap export.
Read the answer →05MCS certification is what makes export payments and loans possible; roof damage comes from bodged fixings.
Read the answer →The calculator has a dial for each of these.
Estimate your solar payback →Spot a bad install
Hooks go into the rafters under lifted tiles, then the tiles go back flat. Lifted or broken edges mean water gets in.
Pigeons nest under panels. Mesh fitted at install, outside the nesting season, is far cheaper than fitting it later.
Cables should be clipped clear of the roof, not draped over tiles or hanging under the array where they chafe.
Never go on the roof or open an isolator. BRE found most solar fires started at DC isolators and connectors — look for cracked cases, rust or scorching without touching anything.
Grants, VAT and export payments
Support differs by nation and changes often. Every line below was checked on 24 September 2026; the full detail and sources are on the question pages.
On installed solar and batteries until 31 March 2027, then 5%.
Free solar and, where it helps, a battery for owner-occupiers with EPC D–G and household income of £36,000 or less (or means-tested benefits). Runs to March 2028.
Funded solar for eligible low-income homes with electric or heat pump heating — ends 31 December 2026.
Government-backed low-interest loans from September 2026; needs an MCS installer. Up to £15,000 for a battery.
Suppliers must pay for export — 3–6p basic, about 12p as an import customer, 15–25p on supplier-install exclusives.
Eligibility, availability and rates change — check the official source before you commit to work. This page does not assess eligibility or submit an application.
What grants and finance are available? →Dated answers with their sources, generated from the research knowledge base.
Estimate your solar payback →Already have solar?
Cleaning intervals, birds, inverter life and what "underperforming" actually means against the MCS estimate.
Solar maintenance →Manufacturer meanings for more than 25 brands, and the few checks a homeowner can safely make.
Solar error codes →Ten questions give you a generation range, the share of your electricity solar could cover, the money and the payback — with dials for panels, battery and tariffs. An MCS installer's site survey and performance estimate come next.
