UK sizing guide for a home solar system How many solar panels do I need?
Most UK homes fit between 4 and 16 panels. A typical solar panel system is about 4.5 kWp, which is around 10 of today's panels. How many solar panels you need comes down to three things: how much electricity you use, how much roof space you have, and which way it faces.
In this guide
How many solar panels do I need in the UK? Quick guide by house type
| House | Panels (about) | System size with 450 W panels |
|---|---|---|
| Mid-terrace | 4 | about 1.8 kWp |
| End-terrace or semi-detached | 8 | about 3.6 kWp |
| Small detached | 12 | about 5.4 kWp |
| Large detached | 16 | about 7.2 kWp |
Panel counts are the Energy Saving Trust's rough guide. System sizes assume 450 W panels, typical in 2026. Roof shape matters more than house type, so treat this as a starting point.
For a better idea of how many panels you need, work through the four steps below. You only need a recent bill and a rough idea of your roof.
Step 1: your annual electricity use
Find your annual electricity usage on a bill or in your supplier's app, in kilowatt hours (kWh). If you can't, Ofgem's typical figures, updated in July 2026, are a fair guide to annual electricity consumption:
| Household | Yearly use |
|---|---|
| Low (often a smaller home, one or two people) | 1,600 kWh |
| Medium | 2,500 kWh |
| High | 3,800 kWh |
Add more if you have, or are planning, an electric car or a heat pump. Both can add thousands of kWh a year. If one is likely in the next few years, it's usually simpler to allow for it now than to add panels later.
Step 2: how much electricity each panel makes
How much a system produces depends on its size in kilowatt peak (kWp), the roof's direction and shade, and the weather that year. Across the UK, each kWp of panels made somewhere between about 805 kWh (2024, a dull year) and 970 kWh (2025, a sunny one) a year, based on government figures. A good working figure is around 850 to 900 kWh per kWp on a decent roof.
A 450 W panel is 0.45 kWp, so it makes roughly 380 to 400 kWh a year.
Peak sunlight hours
Some solar panel calculators use peak sunlight hours instead: the number of hours a day at full strength that would give the same energy. The government figures above work out at about 2.2 to 2.7 peak sunlight hours a day, averaged across the year. Treat higher figures from overseas calculators with care.
Local sunlight conditions
Where you live matters less than you might think, because how much sunlight your roof gets depends more on its direction and shade. Which?'s modelling for a south-facing roof gives about 910 kWh per kWp in London and about 830 in Edinburgh, a gap of around 10%. A shaded or north-facing roof costs more than that.
Step 3: work out the number of solar panels you need
Divide your yearly energy usage by what each panel makes. That's the basic answer to "how many solar panels do I need?":
| Yearly use | System size | Panels (about) |
|---|---|---|
| 1,600 kWh | about 1.8 kWp | 4 |
| 2,500 kWh | about 2.8 kWp | 6 to 7 |
| 3,800 kWh | about 4.3 kWp | 9 to 10 |
| 6,000 kWh (with an electric car or heat pump) | about 6.8 kWp | 15 |
Why many people fit more than their electricity bills suggest
Panels make most in summer and around midday, so you'll export a lot of what they make and still buy power in the evenings and winter. If you have the roof, a bigger system makes more electricity all year, so more of your winter use is covered and there's more to export or store. With a battery or an electric car, filling the roof often makes sense.
A quicker way: a solar panel calculator
The Energy Saving Trust's Solar Energy Calculator asks a few questions about your home and estimates how many solar panels suit your roof space, what they might cost and what they could save. Like any calculator, it gives an estimate: a survey then confirms what actually fits.
Step 4: how many solar panels can you fit on your roof?
- A typical 2026 home panel is about 1.76 m by 1.13 m, so roughly 2 m² each.
- MCS installation rules keep panels back from the edges of domestic roofs, usually by 400 mm, unless extra measures are taken. That margin matters most on small roofs.
- Chimneys, vents, roof windows and dormers all take space.
- The Energy Saving Trust says a 4.5 kWp system typically covers 20 to 30 m² of roof.
As a rough guide, divide your available roof space in square metres by 2, then allow for the edge margins and anything in the way. Panels come in fixed sizes, so the shape of each slope affects how many panels fit as well as its area.
If you have limited roof space
Two things help. Higher efficiency panels make more electricity from each square metre, so you need fewer panels for the same output (more on this under solar panel sizes, below). And a second slope facing east or west can add panels without needing south-facing space.
Measuring from a satellite image is a start, and before anything is fitted the technical survey measures on site, because hips, valleys and edge margins make a real difference to the count.
Solar panel sizes
Common home panels are all a similar size. What varies is how much power each one makes.
| Panel type | Size | Weight | Power | Efficiency |
|---|---|---|---|---|
| Typical 2026 home panel (54 cells) | about 1.73 to 1.80 m by 1.13 to 1.21 m, 30 mm deep | about 21 to 23 kg | 450 to 485 W | about 22.6% to 24.3% |
| Older PERC panel | about 1.72 m by 1.13 m | not listed | around 415 W | about 21% |
Ranges are taken from current datasheets for common 54-cell home panels. They are examples of what's typical, not a list of the panels we fit.
Why solar panel efficiency matters
Panel efficiency is the share of the sunlight landing on a panel that it turns into electricity. Industry figures for 2026 put the older PERC type at about 21.7%, and the newer TOPCon, heterojunction and back-contact types at about 23.5% to 24%. Higher efficiency panels have a higher wattage for the same size, so you need fewer of them for the same system size. That matters most when roof space is the limit.
For example, ten 475 W panels make a 4.75 kWp system, while ten 415 W panels make 4.15 kWp: about 14% more power from the same roof. If your roof has room to spare, you can simply fit more panels instead.
Which way should solar panels face?
| Direction | Output |
|---|---|
| South | Best |
| East or west | about 15 to 20% less |
| North | about 30% less |
Sources: Energy Saving Trust (east and west), Which? (north).
East and west are better than they sound. Panels on both slopes spread generation across the morning and evening, when many households use more. North-facing roofs are usually only worth it alongside other slopes, or on a low pitch.
Direction isn't the only thing that cuts output. Shade from trees, chimneys or nearby buildings matters too: Which? says heavy shading can cost up to half. On a shaded or east-west roof you'll need more panels for the same yearly output.
Does battery storage change how many panels you need?
A solar battery doesn't change how much electricity your panels make, but it changes how much of it you use. It stores excess energy from the day for the evening, so a bigger solar array is worth more with a battery than without one, especially if your electricity usage is mostly in the evening. If you're planning a battery, size the panels with it in mind.
A battery can also be added later, including to panels another company fitted. Our guide to what size solar battery you need covers the battery side.
How many solar panels to power a house on its own?
Generating as much as you use over a year isn't the same as running the house on solar power. Solar panels generate electricity only in daylight, and very little in winter: in 2025, October to December produced only about a tenth of the UK's solar output for the year.
- What owners report. In a 2024 Which? survey, about a quarter of solar owners said their panels met half to three-quarters of their yearly electricity use, and nearly 30% said a quarter to a half.
- What a battery adds. It moves daytime surplus into the evening, so you import less. In winter there's little surplus to store, so most homes still buy some power.
- Power cuts. Without extra equipment, panels and batteries don't supply your home when the grid goes down. They switch off for safety.
So for most UK homes, the aim is to cut your energy bills, not to stop buying electricity altogether.
One more limit: your grid connection
On a normal single-phase home supply, systems with an inverter up to 3.68 kW can be fitted and then notified to the network operator. That's about 8 panels of 450 W. The limit applies to the inverter's rating, so the panels themselves can add up to a little more. Bigger systems need the network operator's approval first. That's rarely a barrier, but it can add a few weeks, and sometimes means limiting what the system exports.
Questions people ask
How many solar panels do I need to power a house?
To generate the same as a typical home uses in a year (2,500 kWh), about 6 or 7 panels of 450 W. Many people fit 8 to 12 to cover more of their winter use and export the surplus.
How many solar panels do I need for a three bedroom house?
The Energy Saving Trust's rough guide goes by house type, not bedrooms: about 8 panels for an end-terrace or semi-detached house, 12 for a small detached house and 16 for a large one. Your yearly electricity use and your roof decide the real number.
Can 4 solar panels power a house?
Four 450 W panels make roughly 1,450 to 1,750 kWh a year, about what Ofgem counts as low household use. But they make most of it on summer days, so they can't power a house through the evening or winter on their own.
Is a 10 kW solar system enough to run a house?
Over a year it would make roughly 8,000 to 9,700 kWh, more than three times typical use. It needs about 22 panels of 450 W, and on a single-phase supply the network operator must approve it first. It still won't run the house at night without a battery.
What size are solar panels?
A typical 2026 home panel is about 1.76 m by 1.13 m and weighs around 21 kg.
Can I have too many solar panels?
You can have more than you'll use, which is fine if you export the rest or have a battery. Systems over 3.68 kW on a single-phase supply need the network operator's approval first.
Is my home suitable for solar panels?
Most are. You need a roof in reasonable condition facing anywhere from east through south to west, without heavy shade. Listed buildings need consent. A free consultation gives you a clear answer.
Read next
Sources
Figures and rules on this page were checked on 11 October 2026. Schemes, tariffs and prices change, so check the latest before you decide.
- Energy Saving Trust: Rooftop solar panel installation, updated 1 October 2026
- Energy Saving Trust: Solar panels, costs, savings and benefits, updated 1 October 2026
- Energy Saving Trust: Solar Energy Calculator, checked 11 October 2026
- Ofgem: Review of typical domestic consumption values, decision, 27 May 2026
- DESNZ: Digest of UK Energy Statistics 2026, chapter 6 (renewables), 2026
- Which?: Are solar panels worth it?, 15 May 2026
- Which?: Solar panels, how much of your electricity can they produce?, 27 June 2024
- DESNZ: Energy Trends March 2026, 2 April 2026
- Energy Saving Trust: Solar power fact check, updated 13 August 2026
- Trina Solar: Vertex S+ NEG9R.28 datasheet, 2026
- AIKO: Neostar 2P54 datasheet, checked 11 October 2026
- LONGi: LR7-54HTH datasheet, May 2024
- REC: Alpha Pure-RX datasheet, August 2024
- PV Tech: ITRPV 2026 roadmap, 25 June 2026
- MCS: MIS 3002 Solar PV installation standard, issue 1.0, January 2025
- Which?: Solar panels buying advice, 12 August 2026
- Energy Networks Association: G98 single premises summary guide, checked 11 October 2026
- Electricity North West: G98 small scale connections, checked 11 October 2026
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