Most solar advice assumes the roof is the constraint. In Esher it often isn’t. At the 2021 Census, 1,469 of Esher ward’s 3,583 dwellings were detached — 41.0% — and a further 23.7% were semi-detached, against 13.7% terraced and 16.9% purpose-built flats. On a big roof the temptation is to fill it. This guide sets out a better order of questions: how much electricity the house uses, what the panels would actually generate in Esher, what a battery changes, and what a larger system means for the grid paperwork.
Start from the electricity you use, not the roof you have
The Energy Saving Trust describes the average home system as about 4.5 kWp — the maximum output in ideal conditions — covering 20 to 30 square metres of roof with around twelve panels, and costing about £7,600 installed (their figures, updated 27 August 2026). Residential installations carry 0% VAT until 31 March 2027, after which the rate reverts to 5%.
Those are national averages. A large Esher house may use more electricity than the average home, particularly with an electric car or a heat pump, and a household that is out all day will use less of its own generation than one that is at home. The quantity that decides whether extra panels pay is the share of their output you would use yourself rather than export. Electricity you use at home replaces power you would otherwise buy; electricity you export earns whatever your export tariff pays. The first is usually worth more than the second, which is why sizing starts with your bills and, if you have one, your smart-meter data.
What panels generate on an Esher roof
Rather than use a national yield, we ran the European Commission’s PVGIS 5.3 tool for Esher itself. A 4 kWp array at 35°, facing due south, with 14% system losses and building-mounted, is estimated at about 3,989 kWh a year — roughly 997 kWh per kWp — with year-to-year variation of around ±157 kWh (PVGIS-SARAH3 data, 2005–2023, run 17 September 2026).
Scaled by capacity on the same assumptions, that gives a rough sense of the options:
| System size | Estimated generation a year (south, 35°) |
|---|---|
| 4 kWp | about 3,989 kWh (the PVGIS run) |
| 4.5 kWp | about 4,490 kWh |
| 6 kWp | about 5,980 kWh |
| 8 kWp | about 7,980 kWh |
Two cautions apply to every row. Direction matters: the Energy Saving Trust notes that a system facing east or west tends to get around 15–20% less energy than one facing directly south. And shade matters more than size — trees, chimneys and neighbouring buildings can take a larger bite out of a big array than an extra panel adds.
Where a battery fits
A battery moves daytime generation into the evening, or lets you charge from the grid when a tariff is cheap. The Energy Saving Trust’s figures (updated 19 August 2026) are the honest frame: battery storage ranges from £1,500 to £10,000, a 5 kWh system costs around £4,600, a typical home system might be 10 kWh, and the typical lifespan is about 10 to 12 years. Its own summary is that savings can be significant but won’t always be enough on their own to justify the battery.
In practice a battery tends to earn its keep in two situations: a large array that would otherwise export a big share of its output while the household is out, and a household on a time-of-use tariff that can shift evening demand into cheaper hours. A household that already uses most of its generation during the day gains less. That is a calculation to run with your usage, not a default to add because the roof is large. Our page on home battery storage explains how we size one.
A larger inverter changes the grid paperwork
Esher’s KT10 postcode is in UK Power Networks’ area, and every grid-connected system has to be registered with it. The dividing line sits at 16 A — 3.68 kW — per phase of inverter capacity. At or below that, a type-tested system can be installed first and notified within 28 days under Engineering Recommendation G98. Above it, the connection falls under G99: an application goes to the network operator and is assessed before the system is installed, which adds time to the programme.
A battery’s inverter counts towards that total alongside the solar inverter. Many single-phase homes that want a large array and a battery therefore end up on the G99 route, and the design stage should allow for it. Your installer submits either form; it is worth knowing which applies before a start date is agreed.
What exported electricity earns
If a large array exports a lot, the Smart Export Guarantee matters. Under Ofgem’s rules a Smart Export Guarantee rate must always be above zero, but each supplier sets its own rate, contract length and terms. To receive a tariff, GOV.UK says you need a meter capable of half-hourly export readings — typically a smart meter — and an installation and installer certified through the Microgeneration Certification Scheme or an accredited equivalent.
Checking the numbers before you commit
Elmbridge residents can also compare a group-buying offer: the county scheme now trades as Switch Together, and its Elmbridge page was inviting registrations, without naming round dates, when we checked on 17 September 2026. Whichever quotes you gather, compare them on the same specification — panel count and wattage, inverter size, battery capacity, warranty terms and who handles the network application.
Our solar panels Esher page sets out the local picture, including Esher’s two conservation areas and the full PVGIS estimate, and the savings calculator lets you test your own bills against it before you speak to anyone.
Sources: ONS Census 2021, TS044 and TS054, Esher ward via Nomis; European Commission JRC, PVGIS 5.3 (run 17 September 2026); Energy Saving Trust, Solar panels (updated 27 August 2026) and Battery storage (updated 19 August 2026); HMRC VAT Notice 708/6; Energy Networks Association, EREC G98 and G99; UK Power Networks; Ofgem, Smart Export Guarantee; GOV.UK, Smart Export Guarantee; Switch Together, Elmbridge page (read 17 September 2026).