Open book

Sources and dates

Every figure on this site comes from a published source. We check them regularly and show the date. Prices and rates change, so treat all figures as estimates.

GOV.UK, VAT Notice 708/6: energy-saving materials. Zero rate 1 May 2023 to 31 March 2027, then 5%. Batteries installed in homes covered from 1 February 2024. Source (Read 7 October 2026)
Ofgem, price cap unit rates: electricity 26.32p per kWh and 54.83p a day standing charge, 1 October to 31 December 2026; no VAT on electricity 1 October 2026 to 31 March 2027. Source (Read 7 October 2026)
Ofgem, Smart Export Guarantee: suppliers set the rate and terms, and rates must be above zero. Source (Read 7 October 2026)
Supplier export rates, read on each supplier's own page: Octopus SEG 4.1p and Outgoing Octopus 12p; British Gas Export Premium 12p (page updated 27 August 2026); E.ON Next 6p, 13p and 17.5p; EDF 3.0p, 5.6p, 13p and 18p. Source (Read 7 October 2026)
Energy Saving Trust, solar panels: about £7,600 for a typical 4.5 kWp system; payback about 9 years in London on July 2026 fuel prices; panels last 25 years or more; no dedicated UK Government grants. Source (Updated 1 October 2026)
Energy Saving Trust, battery storage: £1,500 to £10,000, about £4,600 for 5 kWh; typical life about 10 to 12 years. Source (Updated 6 October 2026)
Energy Saving Trust, plug-in solar: legal in Great Britain from 27 August 2026; from about £450; about £70 to £100 a year; register before use; no integrated battery. Source (Updated 1 October 2026)
GOV.UK, plug-in solar panels come to market (26 August 2026): up to 800W, up to £110 a year. Source (Published 26 August 2026)
legislation.gov.uk, SI 2026/896, amending the GPDO Part 14 (in force 27 August 2026): plug-in solar and timber walls and fences. Source (Signed 29 July 2026)
legislation.gov.uk, SI 2026/1056, amending GPDO Part 2 charge point rights (in force 21 October 2026). Source (Signed 25 September 2026)
legislation.gov.uk, GPDO 2015 Schedule 2 Part 14: solar equipment on dwellings, conditions on siting. Source (Read 7 October 2026)
Octopus Energy, Intelligent Octopus Go: 7.6p per kWh for eligible smart charging, 11:30pm to 5:30am, fixed rates only; EV cost sum 7,000 miles about £160. Cosy Octopus cheap rates 51% below the day rate. Source (Read 7 October 2026)
ONS Census 2021 via Nomis, accommodation type for the Beltinge, Greenhill, Herne & Broomfield, Heron, Reculver and West Bay wards (18,158 households, summed by us). Source (Census 2021)
Planning data platform, conservation area records supplied by Canterbury City Council (98 records across the district; seven that by our reading cover parts of Herne Bay, Herne and Reculver). The council's own page gave no readable list, so the count is ours. Source (Read 7 October 2026)
Wikipedia place pages for Herne Bay, Reculver, Beltinge, Herne, Hampton-on-Sea, Herne Bay Pier, the Clock Tower and Herne Windmill (history, geography and landmarks). Source (Read 7 October 2026)
postcodes.io, ward of sampled postcodes in CT6 5 to CT6 8 (our sample). Source (Read 7 October 2026)
DESNZ, Quarterly Energy Prices, September 2026 (statistical release of 29 September 2026). Source (Published 29 September 2026)
DESNZ, Digest of UK Energy Statistics (DUKES) 2026, chapters 1 to 7 (published 30 July 2026). Source (Published 30 July 2026)
DESNZ, Boiler Upgrade Scheme: notice of approved grant categories and values (updated 29 September 2026). Source (Updated 29 September 2026)
UK Power Networks annual review: South Eastern Power Networks serves South London, Kent, East Sussex and parts of Surrey and West Sussex. Source (Read 7 October 2026)

What is our own estimate

The cost ranges and savings on our cost pages are our own estimates, built on the sources above. They assume a roof making about 900 kWh for each kWp a year, 35% of solar power used in the house, a battery that loses about 10% of power, and a house using 3,000 kWh a year. They are not quotes. Last reviewed 7 October 2026.