Battery storage in Westerham

Westerham at a glance

Oil tanks, electric heating and what the battery covers

At the 2021 Census, 1,257 of the 1,935 households in the Westerham and Crockham Hill ward heated with mains gas alone: 65.0%, against 72.3% across Sevenoaks District. Oil accounts for most of the difference. 221 households (11.4%) relied on it alone, against 6.7% in the district, and another 36 used tank or bottled gas, so more than one household in eight in the ward heats from a tank rather than the gas main.

That fuel decides what a battery has to cover after dark. Where an oil or gas boiler does the heating, the battery carries lighting, cooking and appliances, and it is sized from the electricity bills the house already runs up. The 143 households on electric central heating alone (7.4%, against 7.0% in the district) are the opposite case: their demand peaks in winter, when a TN16 roof generates least, so their battery is designed around a full year of usage. If a heat pump might replace an oil boiler in the next few years, say so at the survey, because it would move the house from the first group into the second.

4,164 kWh a year, and how much of it stays in the house

PVGIS, the EU Joint Research Centre’s model, gives 4,164 kWh a year for an unshaded 4 kWp array facing south at 35° at TN16 1AA, close to Sevenoaks town’s 4,192. The value table further down applies the Microgeneration Certification Scheme’s self-consumption tables to that figure, for a household using 2,500 to 2,999 kWh a year and at home for half the day. Without a battery, about 750 kWh (18%) is used in the house and the rest is exported; with a 10 kWh battery, about 2,332 kWh (56%) is used at home. A house that uses more electricity than that gets a different split, so the survey works from your own usage profile.

Every Coutts Electrical guide-priced system includes 10kWh of battery capacity, and the prices are on solar panel cost in Kent. Our guide to whether solar is worth it in Kent works the payback through with and without a battery.

Adding storage to panels already on the roof

DESNZ counted 3,282 solar PV installations in Sevenoaks District at the end of 2025, 84% more than the 1,783 counted at the end of 2020. The figure covers the whole district, Sevenoaks, Swanley and Edenbridge included, so it cannot say how many are on Westerham roofs. It does show that many of the district’s arrays were in place well before February 2024, when batteries installed in homes became zero-rated for VAT, including batteries added to existing panels. For one of those houses, the survey starts with the installation and its inverter and confirms what can be integrated safely before anything is quoted. Installation, commissioning and app monitoring are covered on our battery storage service page.

UK Power Networks, G98 and the older inverter

A lookup on TN16 1AA returns grid supply point group _J, so UK Power Networks runs Westerham’s network under its South Eastern Power Networks licence. Storage counts towards the connection limit alongside generation. G98 covers a property’s total up to 16 A per phase, 3.68 kW on a single-phase supply, and UK Power Networks is notified within 28 days of commissioning; above that, a G99 application is made, and answered, before anything is installed.

On a house with older panels, the solar inverter’s rating is the starting figure. A battery with its own inverter adds that rating to it, so a system that sat inside G98 can need G99 once storage joins it. Our guide to choosing a solar inverter explains how a hybrid inverter, which handles the panels and the stored power in one unit, differs from the standard kind.

Owners, landlords, flats over shops and listed buildings

At the 2021 Census, 1,306 of the ward’s 1,936 households owned their home, 685 outright and 621 with a mortgage or loan: 67.5%, against 71.5% across the district. A battery is fixed to the building and wired into its supply, so for the 16.1% renting privately, the 14.7% renting from a social landlord and the 1.6% in shared ownership, the landlord or housing provider is the one to ask first. Houses held 84.7% of households. Of the 15.2% in flats, 31 households lived in a commercial building, such as over a shop, where the building’s owner has to agree before a battery goes anywhere.

The Westerham Conservation Area takes in the Green, St Mary’s Church and Quebec House, which is listed grade I, and Sevenoaks District Council’s 2015 appraisal counts about 100 listed buildings in its 36 hectares. Two lines in that appraisal matter for a battery. Listing covers a building inside and out, including any object or structure fixed to it, and any structure in the grounds that was there by 1948 is listed as well, so an old outbuilding is not automatically a consent-free position. If your house is listed, ask the council whether the battery, its inverter and their cable runs need Listed Building Consent before the position is fixed.

Westerham is also the first place named in the Environment Agency’s ‘River Darent from Westerham to Sevenoaks’ flood warning area. If your home is inside it, mention it when you book, so the survey weighs it in choosing where the battery goes.

Zero-rated to 31 March 2027

HMRC’s VAT Notice 708/6 has zero-rated batteries installed in homes since 1 February 2024. The relief runs to 31 March 2027, and from 1 April 2027 the rate returns to 5%. Our guide prices are inclusive of VAT currently at 0%, and the written quotation confirms the VAT on your job. Sevenoaks District Council also has its own Warm Homes: Local Grant allocation for lower-income households in homes rated D to G, and DESNZ guidance lets councils fund a battery only alongside new or existing panels, and only where it cuts the household’s bills; solar and battery grants in Kent sets out who qualifies.

Our office at Glebe Farm Business Park, Keston, stands in the London Borough of Bromley, 5.8 miles north-north-west of Westerham in a straight line. For wiring, testing and other electrical work in the house, see our page for an electrician in Westerham.

What a battery could be worth on a Westerham roof

PVGIS 4,164 kWh a year for this town. Illustrative first-year figures, not a guarantee: import 26.32p/kWh (Ofgem energy price cap, 1 Oct – 31 Dec 2026, electricity, Direct Debit, GB average unit rate (26.32p/kWh)); export 12p/kWh (Outgoing Octopus Smart Export Guarantee tariff, 12p/kWh variable (Octopus customers with a half-hourly export meter), read 15 Oct 2026); self-use from MCS MGD 003 Issue 2.0 self-consumption tables, 2,500–2,999 kWh use, occupied half the day. Coutts' guide price for 4kWp with 10kWh battery capacity is from £9,500, inclusive of VAT at 0% (the relief runs to 31 March 2027). Full worked example: solar panel cost in Kent; schemes: solar and battery grants in Kent.

What every battery storage job includes

• 10kWh battery capacity included in every guide-priced system
• Installed and commissioned alongside the array by our own engineers
• App monitoring set up at handover so you can see storage and use
• Retrofit to an existing solar array is possible — we survey first