A battery quote for a semi in Caterham Valley and one for a detached house on the Hill can differ by thousands of pounds for reasons that have little to do with the battery itself. Size, whether panels are going on at the same time, and what UK Power Networks needs to be told all move the number. This guide works through those sums with published figures, and our page on battery storage in Caterham covers the local grid and housing in more detail.
We do not print our own prices. Every figure below belongs to the Energy Saving Trust, DESNZ or HMRC, and each is labelled. Where a figure is our own arithmetic on theirs, we say so. The point is to give a Caterham household a yardstick for any quote, ours included.
Two national figures, measuring different things
The Energy Saving Trust’s battery page, updated 19 August 2026, gives a range of £1,500 to £10,000, says a 5 kWh system costs around £4,600, and suggests a typical home system might be 10 kWh. It also says the typical lifespan is about 10 to 12 years and that there is no exact formula for working out what size you need.
DESNZ measures something narrower: the cost of MCS-registered battery installations in existing homes in the 2025/26 financial year, equipment plus installation plus VAT where it applied, with any solar fitted alongside excluded. Its three size bands show the cost per kWh falling as batteries get bigger:
| DESNZ band | Average size | Mean cost per kWh | Average job (our arithmetic) |
|---|---|---|---|
| 1 to 5.99 kWh | 5.14 kWh | £1,280 | about £6,570 |
| 6 to 10.99 kWh | 9.80 kWh | £870 | about £8,520 |
| 11 to 29.99 kWh | 15.48 kWh | £670 | about £10,380 |
The two sources do not agree on a small battery: the Trust’s £4,600 for 5 kWh sits well below DESNZ’s average small job. That is not a contradiction to resolve, just a reminder that one is a guide figure and the other an average of real MCS-registered jobs, VAT included. A Caterham quote that sits between the two is not unusual.
A worked example for a Caterham Valley semi
Census 2021 figures for the Caterham Valley MSOA show 21.4% of homes are semi-detached and 35.3% detached, so take a semi with a pitched roof and no panels yet. Three options, priced on the published figures alone:
- A 5 kWh battery on its own: around £4,600 on the Trust’s figure.
- A typical 4.5 kWp array with a 5 kWh battery, fitted together: around £7,600 plus around £4,600, about £12,200 on the Trust’s two figures (our arithmetic). The Trust says fitting storage at the same time as panels costs less than a separate visit later.
- A battery of about 10 kWh on its own: about £8,520 as the DESNZ average job in the 6 to 10.99 kWh band (our arithmetic).
None of those is a quote. They show the order of magnitude a CR3 quote should sit in, and the size step from 5 kWh to 10 kWh is where most of the difference lies.
Why the bigger battery is not automatically better in CR3
The site’s PVGIS 5.3 run for Caterham, a 4 kWp array facing due south at 35° with 14% losses, gives about 491 kWh in June and about 135 kWh in December. On our arithmetic that is roughly 16 kWh a day in June and just over 4 kWh a day in December from an unshaded roof. In summer a 4 kWp roof can fill a 10 kWh battery with daylight to spare; in December it cannot fill a 5 kWh one on an average day, even if the house used nothing during daylight hours.
So the extra money for a bigger battery buys capacity that a Caterham roof will mostly fill between spring and autumn. Whether that suits you depends on your evening use and your tariff, which is why the Trust says sizing has no exact formula. Our guide to what size home battery you need goes through the questions in order.
The VAT window
HMRC’s VAT Notice 708/6 zero-rates residential installations of solar panels and batteries in Great Britain until 31 March 2027, and the rate reverts to the reduced 5% from 1 April 2027. The relief covers a battery fitted on its own as well as one fitted with panels. A home EV charger is not on the list and carries 20%. For a Caterham household, the practical point is to check that a quote states the rate it assumes and the date the work is planned. The detail is in our post on VAT on solar panels and batteries.
What moves a Caterham quote
Who controls the wall. Purpose-built flats are 30.5% of homes in the Caterham Valley MSOA, many near the station. A flat may have room inside for a battery, but cabling and any external work usually need the freeholder’s agreement, and that comes before price.
Whether panels are already up. DESNZ records about 2,754 solar PV installations across Tandridge at the end of 2025, as first published (every size, not just homes). Adding a battery to an existing array depends on the inverter already fitted, which a survey checks.
Which way the roof faces, if panels are part of it. On the site’s PVGIS runs for Caterham Valley, a due-south roof gives about 4,008 kWh a year from 4 kWp, an east-facing one about 3,219 kWh and a west-facing one about 3,173 kWh. On a valley town’s mixed slopes, that changes how much surplus a battery can store.
The grid paperwork. Caterham’s town centre sits in UK Power Networks’ South Eastern Power Networks licence area. Under G98, a system up to 16 A per phase (3.68 kW) is notified before commissioning or within 28 days of it; above that, G99 approval comes before work starts, and a 4 kW inverter, at 17.39 A, is just over the line. UK Power Networks says it automatically approves applications where the maximum export, after any export limitation, is under 5 kW, and that there is nothing to pay it unless your supply needs an upgrade.
Getting a figure for your own house
The published averages get you to a range; only a survey gets you to a price. If panels are part of the plan, our page on solar panels in Caterham covers the roof side, and the wider Surrey solar panels hub covers schemes and planning across the county. When you compare quotes, compare the battery’s usable capacity, the inverter, the warranty terms and the grid paperwork line by line, not just the total.
Sources: Energy Saving Trust, Battery storage (updated 19 August 2026) and Solar panels: costs, savings and benefits explained (updated 27 August 2026); DESNZ, MCS-certified domestic battery installation statistics (28 May 2026); DESNZ, Renewable electricity by local authority 2014 to 2025 (29 September 2026); HMRC, VAT Notice 708/6; PVGIS 5.3, European Commission Joint Research Centre (PVGIS-SARAH3 2005–2023; monthly run 15 October 2026, orientation runs 17 September 2026); ONS Census 2021, TS044 for the Caterham Valley MSOA (censusdata.uk); UK Power Networks, licence boundaries open data and Solar and storage: cost, time and what’s involved (read 15 October 2026); Energy Networks Association, EREC G98 Issue 2 (10 March 2025).