Most three-bedroom homes in England need 7 to 10 solar panels. A typical household uses about 2,700 kWh of electricity a year, and one modern 440W panel makes roughly 390 to 510 kWh a year depending on where you live, so 7 panels (about 3kW) roughly cover the year and 10 panels (4.4kW) leave spare to export or to charge a car. The right number for you comes down to three things: your usage, your location and your roof.
- 2,700 kWh typical yearly electricity use in a two or three bed home (Ofgem)
- 390 to 510 kWh made by one 440W panel a year, Manchester to Brighton
- 7 to 10 panels for most three bed houses
- About 2m² of roof per panel, plus edge margins
Work it out in four steps
This is the same method our surveyors start with. You need your annual electricity use (it is on your bill or your supplier's app, usually shown as kWh per year) and a rough idea of your roof.
- Find your yearly usage in kWh. If you cannot find it, Ofgem's typical figures are 1,800 kWh for a flat or small house, 2,700 kWh for a two to three bed home and 4,100 kWh for a four bed or larger home.
- Add anything you are planning. An electric car adds its miles divided by its efficiency. At 7,000 miles and 3.5 miles per kWh that is 7,000 / 3.5 = 2,000 kWh. A heat pump adds a lot too, though most of that falls in winter when solar is weakest.
- Work out what one panel makes where you live. Multiply the panel size in kW by your local yield. For a 440W panel in Birmingham: 0.44 x 972 = 428 kWh a year. In Manchester it is 0.44 x 886 = 390 kWh; in Brighton 0.44 x 1,159 = 510 kWh.
- Divide, then round up. Usage / output per panel = panels needed. Then check it fits the roof.
A worked example: a semi in Leeds with an EV on the way
Say you live in Leeds, use 2,700 kWh a year now, and are getting an electric car next year that will cover 7,000 miles.
- Future usage: 2,700 + 2,000 = 4,700 kWh a year.
- Output per 440W panel in Leeds: 0.44 x 946 = 416 kWh a year.
- Panels to match: 4,700 / 416 = 11.3, so 11 to 12 panels, about 4.8 to 5.3kW.
Now the roof. Your rear slope is 7m wide and 4.5m from gutter to ridge. Panels fitted portrait are about 1.13m wide and 1.72m tall. Across: 7 / 1.13 = 6.2, and after leaving a margin at each edge that becomes 5 panels. Up the slope: 4.5 / 1.72 = 2.6, so 2 rows. That is 5 x 2 = 10 panels, 4.4kW.
So the roof limits you to 10 panels, making 10 x 416 = 4,160 kWh a year. That still covers most of your new usage over a year, and a front or side slope could take more if it faces east or west. This is common: on terraced and semi-detached houses, the roof usually sets the number before the bill does.
Panel numbers for different homes
The table uses 440W panels on a south-facing roof in the Midlands (972 kWh per kW per year). The cost column is the national median installed price from the government's 2025/26 MCS data, before any battery, to show how price scales with size.
| Panels | System size | Yearly generation | Roof area of panels | Typically suits | Median market price |
|---|---|---|---|---|---|
| 6 | 2.64kW | 2,566 kWh | 11.7m² | Flat, bungalow, 1 to 2 people | £4,211 |
| 8 | 3.52kW | 3,421 kWh | 15.6m² | Two to three bed, average use | £5,614 |
| 10 | 4.40kW | 4,277 kWh | 19.5m² | Three bed, higher use or home workers | £6,802 |
| 12 | 5.28kW | 5,132 kWh | 23.4m² | Four bed, or three bed with EV | £8,163 |
| 14 | 6.16kW | 5,988 kWh | 27.3m² | Large home, EV, heat pump | £9,523 |
| 16 | 7.04kW | 6,843 kWh | 31.2m² | Large detached, two EVs | £10,884 |
Median prices use £1,595 per kW for systems up to 4kW and £1,546 per kW for 4 to 10kW. Our own 4.4kW, 10-panel system is from £6,495, and our 14-panel 6.2kW system with a 10kWh battery is from £12,495. The solar panel cost guide breaks prices down by size and region.
Why most people should go slightly bigger than their usage
Matching panels to your yearly usage sounds tidy, but it hides a mismatch. Panels make most of their power from April to September and at midday, while most homes use most electricity in the evening and in winter. Even a system that makes exactly your yearly usage will export a lot in summer and import a lot in winter.
Two things make going a bit bigger sensible:
- The cost per kW falls as systems grow. Scaffolding, the inverter and the electrical work cost roughly the same for 8 panels as for 12, so each extra panel is cheaper than the first ones.
- Surplus is paid for. Exported power earns an export tariff, often 12p per kWh or more, so a panel that mostly exports still earns its keep.
There is a limit. HMRC treats export income as tax-free when you do not intend to generate much more than your home uses, and its guidance uses 20% over your own needs as the rule of thumb. For a household using 4,700 kWh that means aiming no higher than about 5,640 kWh a year of generation if you want to be safely inside it. Most domestic roofs never get close.
What changes the number on your roof
Which way the roof faces
South is best. East and west-facing roofs make roughly 15 to 20% less, so you need about one extra panel for every five or six to get the same output. The upside is that an east and west split spreads generation across the morning and evening, when you are more likely to be home to use it. North-facing roofs make much less and are rarely worth covering.
Shading and roof features
Chimneys, vent pipes, dormers, roof windows and hips all take space and cast shade. A hipped roof loses its triangular ends; a dormer bungalow may only have strips either side of the dormer. Our roof suitability guide covers slate, tile and flat roofs in more detail.
Where in England you are
The same 2,700 kWh home needs about 7 panels in Manchester (2,700 / 390 = 6.9) and about 6 in Brighton (2,700 / 510 = 5.3). It is one panel of difference, not a different decision.
Your electricity connection
Most homes have a single-phase supply. If the inverter is rated at up to 3.68kW we fit and then notify the network operator under the G98 rules. A larger inverter needs a G99 application approved before switch-on, which can take several weeks and occasionally comes back with an export limit in busy areas. Many 4.4kW systems use a 3.6kW inverter for this reason: the panels rarely all produce full power at once, so very little is lost. We make whichever application is needed.
Do you need a battery to go with them?
Not to decide on panel numbers, but it changes how much of your solar you use. Without a battery, a typical home uses roughly a third of what its panels make; with a suitably sized battery that can roughly double. If you are fitting 10 or more panels and are out during the day, a battery is worth pricing at the same time, because fitting both together is cheaper than adding one later. See what size solar battery you need.
Rule of thumb: take your yearly kWh, divide by 400 in the north, 430 in the Midlands and London, or 480 on the south coast, and round up. That gives the number of 440W panels. Then let the roof have the final say.
Winter matters less than you think for sizing
People sometimes ask for enough panels to cover December. It is not practical: output in the darkest months is a small fraction of summer output, so a system sized for winter would be enormous and export most of its power for eight months a year. Size for the year, use a battery or an off-peak tariff for winter evenings, and read do solar panels work in winter for what to expect month by month.
If you want a number for your own roof, the solar savings calculator will give you an estimate in a minute, and our free survey, in person or from photos and satellite imagery, confirms exactly how many panels fit before you get a fixed written price.
Sources
Typical household usage: Ofgem, average gas and electricity usage. Median installed cost per kW: DESNZ and MCS solar PV cost data 2025/26. Export income and tax: HMRC BIM40520. Grid connection rules: Energy Networks Association, G98 and G99. Generation per kW: our own runs of the European Commission's PVGIS tool for each town, south-facing at 35 degrees.
