Key figures
The numbers behind our guides and the savings estimator, each with its source and the date we checked it. Prices and rates change — check the source for the latest.
- 26.32p per kWhElectricity unit rate (Ofgem price cap)GB average, Direct Debit, single rate, 1 October – 31 December 2026. Varies by region and tariff. Source: Ofgem: Energy price cap unit rates and standing charges · checked 9 Oct 2026
- 54.83p a dayElectricity standing charge (Ofgem price cap)GB average, Direct Debit, 1 October – 31 December 2026. Source: Ofgem: Energy price cap unit rates and standing charges · checked 9 Oct 2026
- 2,500 kWh a yearTypical household electricity useOfgem’s typical medium-use figure since 1 July 2026 (was 2,700 kWh). Source: Ofgem: Summary of changes to energy price cap 1 Oct–31 Dec 2026 · checked 9 Oct 2026
- 0%VAT on household electricity (Great Britain)1 October 2026 – 31 March 2027. Northern Ireland stays at 5%. Source: HMRC Brief 10 (2026): Temporary zero rate of VAT for domestic electricity in GB · checked 9 Oct 2026
- 0%VAT on installed home solar and batteriesUntil 31 March 2027, then due to return to 5%. Batteries included since 1 February 2024. Source: HMRC VAT Notice 708/6: Energy-saving materials and heating equipment · checked 9 Oct 2026
- £1,595 per kWMedian installed cost, systems up to 4 kWGreat Britain, 2025/26, MCS-registered installs. Includes VAT and installation; excludes batteries. Source: DESNZ: Solar PV cost data · checked 9 Oct 2026
- £1,546 per kWMedian installed cost, 4–10 kWGreat Britain, 2025/26. Source: DESNZ: Solar PV cost data · checked 9 Oct 2026
- £1,204 per kWMedian installed cost, 10–50 kWGreat Britain, 2025/26. Source: DESNZ: Solar PV cost data · checked 9 Oct 2026
- About 4.5 kWp, about £7,600Typical home systemEnergy Saving Trust, page updated 1 October 2026. Source: Energy Saving Trust: Solar panels · checked 9 Oct 2026
- 9–12 yearsPayback for a typical systemEnergy Saving Trust, including export payments, July 2026 prices; depends on location and how much you’re at home. Source: Energy Saving Trust: Solar panels · checked 9 Oct 2026
- 736–1,130 kWhYearly output per kWp, south-facing 35° roofMCS figures by postcode zone: Lerwick lowest, Brighton highest; London zone 984. Source: MCS: Irradiance Datasets (kWh/kWp by postcode zone) · checked 9 Oct 2026
- About 80% of southEast- or west-facing roofAt 35° pitch (MCS data). A flat installation gives about 84%. Source: MCS: Irradiance Datasets (kWh/kWp by postcode zone) · checked 9 Oct 2026
- About £4,600Home battery, 5 kWhRange £1,500–£10,000. A typical home battery might be 10 kWh. Source: Energy Saving Trust: Battery storage · checked 9 Oct 2026
- 10–12 yearsBattery lifespanEnergy Saving Trust. Source: Energy Saving Trust: Battery storage · checked 9 Oct 2026
- 25+ years / about 12 yearsPanel and inverter lifeEnergy Saving Trust. Source: Energy Saving Trust: Solar panels · checked 9 Oct 2026
- About 0.5% a yearPanel output loss with ageMedian of nearly 2,000 reported field measurements (NREL review, 2012). Source: NREL/OSTI: Photovoltaic Degradation Rates — An Analytical Review · checked 9 Oct 2026
- 16 A per phaseSmall-system grid connection limit (G98)About 3.68 kW on a single-phase home. Larger systems need network approval first (G99). Source: ENA: Distributed Generation Connection Guide – G98 single premises · checked 9 Oct 2026
- 800 W, one device per homePlug-in solar limitLegal in Great Britain since 27 August 2026; not yet in Northern Ireland. Source: Energy Saving Trust: Plug-in solar panels · checked 9 Oct 2026
- From about £450; about £70–£100 a yearPlug-in solar cost and savingEnergy Saving Trust estimate for an 800 W kit (the government says up to £110 a year). Source: Energy Saving Trust: Plug-in solar panels · checked 9 Oct 2026
- 12p per kWhOutgoing Octopus export rateVariable, for Octopus customers. Checked 9 October 2026. Source: Octopus Energy: Outgoing Octopus export tariffs · checked 9 Oct 2026
- 13p per kWhE.ON Next Export Exclusive12-month fixed, for E.ON Next import customers. Checked 9 October 2026. Source: E.ON Next: Smart Export Guarantee tariffs · checked 9 Oct 2026
- 3p per kWhEDF SEG Export VariableOpen to anyone. Checked 9 October 2026. Source: EDF: Smart Export Guarantee tariffs · checked 9 Oct 2026
- £15,000 solar; £15,000 batteryWarm Homes Loan capsInterest cut by up to 5 percentage points; MCS installer required (scheme rules, September 2026). Source: DESNZ: Warm Homes Loan Scheme – scheme rules (Sept 2026) · checked 9 Oct 2026
- 31 December 2026ECO4 end dateExtended (government response, 23 January 2026). Source: GOV.UK: Extending the ECO4 end date – government response · checked 9 Oct 2026
- 25%Largest deposit advisedCitizens Advice and RECC. Source: Citizens Advice: Find an installer for energy efficiency home improvements · checked 9 Oct 2026
- February 2026 – 31 March 2027MCS:2025 transitionConsumer-code membership becomes voluntary under the new scheme. Source: MCS: Complaints Policy (2026) · checked 9 Oct 2026
- 1 April 2022 – 31 March 2035Business rates exemption for on-site solar (England)Plant and machinery for on-site renewable generation and storage. Source: legislation.gov.uk: Valuation for Rating (Plant and Machinery) (England) (Amendment) Regulations 2022 · checked 9 Oct 2026
- About 23.2 GW, about 2.13 million installationsUK solar capacityEnd of August 2026, provisional government statistics as reported by Solar Power Portal; figures get revised. Source: Solar Power Portal: UK installs record 291,000 solar PV installations in 12 months · checked 9 Oct 2026
The estimator’s starting figures (checked 9 October 2026) are listed on the estimator page. All sources: sources.