How much electricity does a solar panel produce? (UK figures for 2026)

A single modern solar panel in the UK produces roughly 350–450 kWh of electricity a year. That's a 400–450W panel on a decent, unshaded, roughly south-facing roof. As a rule of thumb, every 1 kWp of panels generates around 850–1,000 kWh a year in Britain, so a typical 4 kWp system (about 10 panels) makes 3,400–4,000 kWh a year, which is broadly what an average UK home uses. Real output swings with wattage, roof direction, tilt, shading, and the seasons, so treat any single figure as a starting point, not a promise.

This page is about energy output: what one panel makes, what a whole system makes, what pushes those numbers up or down, and how many panels it takes to cover a home. If you're trying to work out how big a system to buy, the numbers here are the foundation, but the honest answer for your specific roof comes from measuring it, which we'll get to.

One thing up front: our own roof check and Solarable Report are built around solar PV (electricity), which is exactly what this guide is about. So the estimates below aren't generic averages when you run them through the tool, they're modelled on your actual roof.

How much a single solar panel produces

Panel output starts with the panel's rating in watts (its wattage or "peak power", written Wp). Most panels sold for UK homes in 2026 are in the 400–450W band, with premium panels pushing higher. That rating is the power the panel makes under standard test conditions (bright, direct sun). Over a real British year, a panel on a good roof converts that rating into roughly 0.85–0.95 kWh per watt, per year.

Put simply:

Panel rating	Rough annual output (good UK roof)
350W	300–350 kWh/year
400W	340–400 kWh/year
450W	380–440 kWh/year
500W	420–480 kWh/year

So a modern 400–450W panel lands around 350–450 kWh a year. To put that in context, 400 kWh is enough to run a typical fridge-freezer for a year with plenty to spare, or roughly one seventh of an average home's total electricity use, from one panel.

These are typical ranges for a roughly south-facing, unshaded roof. A north-facing panel, a heavily shaded one, or one lying flat can produce a good deal less. That's why "solar panel output" is never a single honest number: it depends on the roof it sits on.

What drives a panel's output

Five things move the number, in roughly this order of impact:

• Wattage. A higher-rated panel makes more from the same patch of roof. It's the headline spec, but it's not the whole story.
• Orientation (which way the roof faces). South is best. East and west perform well, commonly giving around 80–85% of a south roof's output, and spreading generation across morning and evening rather than concentrating it at noon. North-facing roofs are usually a poor bet and often not worth panelling.
• Tilt (roof pitch). A pitch of roughly 30–40 degrees is close to ideal in the UK. Flatter or steeper roofs cost you a little, but rarely enough to rule solar out.
• Shading. Trees, chimneys, dormers, and neighbouring buildings are output killers, and their effect is worse than people expect because shade on one panel can drag down a whole string (which is where different inverter types and optimisers earn their keep). Cloud and shade are covered in full in do solar panels work on cloudy days?.
• Season and weather. UK solar is heavily summer-weighted. A system generates the bulk of its year between roughly April and September, and only around 10–15% of its annual total across November–February. We cover that lopsided year in detail in solar in winter and solar in summer.

Notice that four of those five are about your specific roof, not the panel. That's the crux of this whole topic: the panel's rating is fixed on the box, but what it actually delivers is decided by where it sits.

What a whole system produces

Panels are sold and installed as a system, sized in kilowatts-peak (kWp). The rule of thumb that does most of the work: every 1 kWp generates around 850–1,000 kWh a year on a good UK roof. Multiply up for common system sizes:

System size	Rough panel count	Annual output (good UK roof)
3 kWp	7–8 panels	2,550–3,000 kWh/year
4 kWp	9–10 panels	3,400–4,000 kWh/year
5 kWp	11–13 panels	4,250–5,000 kWh/year
6 kWp	13–15 panels	5,100–6,000 kWh/year

Panel counts vary because they depend on panel wattage: ten 400W panels make a 4 kWp system, but nine 450W panels get you there too. The output range is what matters, and it moves with the same five factors above. A south-facing 4 kWp array with no shading will sit near the top of its range; the same system split east-west with a chimney in the way will sit lower.

For reference, the average domestic system installed in the UK is a bit over 4 kWp, and a 4 kWp system needs roughly 20 square metres of clear roof.

How many solar panels does it take to power a house?

This is the question hiding behind all the output numbers, so here's the plain version. Ofgem's typical medium household uses about 2,700 kWh of electricity a year. A 4 kWp system (around 10 panels) generates roughly 3,400–4,000 kWh a year, so on paper it more than covers an average home's annual use.

The honest catch is the word "annual". Solar generates in the daytime and mostly in summer, while your home draws power in the evenings, at night, and through winter. So even a system that matches your yearly total on paper won't make you self-sufficient. In practice, without a battery, a typical home directly uses somewhere around a third to a half of what its panels generate, and either exports the surplus (earning money through the Smart Export Guarantee) or stores it in a battery for later. A battery meaningfully lifts how much of your own generation you actually use.

So "enough panels to power a house" and "enough panels to cover a house's annual usage" are different questions. Around 10 panels covers the second. The first isn't really achievable with roof solar alone in the British climate, and that's fine: the goal is to cut your bill hard, not to unplug from the grid.

Why your roof beats any average

Every figure on this page is a national average dressed up as a range. Useful for planning, useless for a decision. Your roof faces a specific direction, sits at a specific pitch, and has its own chimney, trees, and neighbours casting their own shadows. Two identical houses on the same street can generate meaningfully different amounts.

This is what our roof check is built to close. It finds your home, estimates your roof's direction and usable area from Google's Solar API, and combines that with regional sunlight data from PVGIS (the EU's solar-yield database) to model an output range for your roof rather than a generic 4 kWp house. The savings calculator then turns that into an estimated annual generation and bill saving. It takes about a minute and it's a far better basis for a decision than any table, including ours.

None of it replaces a proper survey. An MCS-certified installer measuring your roof in person is the only way to a firm system size and a firm quote, and you should always get one before you commit. Our installer directory lists MCS-certified installers covering your postcode.

Frequently asked questions

How much electricity does one solar panel produce in the UK?

A modern 400–450W panel on a good, unshaded, roughly south-facing UK roof produces around 350–450 kWh of electricity a year, or roughly 0.85–0.95 kWh per watt of rating annually. A north-facing, shaded, or flat-lying panel produces less. That single-panel figure is the building block for whole-system output: every 1 kWp of panels generates around 850–1,000 kWh a year.

How much electricity does a 4kW solar system produce per year?

A 4 kWp system (about 10 panels) generates roughly 3,400–4,000 kWh a year on a good UK roof, which is broadly what an average home uses across a year. Where it lands in that range depends on roof direction, pitch, and shading. A south-facing, unshaded array sits near the top; a shaded or poorly oriented one sits lower.

How many solar panels do I need to power my house?

To cover an average UK home's annual electricity use (around 2,700 kWh), you need roughly 10 panels (a 4 kWp system). But because solar generates in the daytime and mostly in summer while you use power in the evenings and winter, matching your annual total on paper doesn't make you self-sufficient. Without a battery, homes typically use a third to a half of what they generate directly and export or store the rest. If you want a size for your specific roof and usage, that's a job for an installer survey after you've run an estimate.

Do solar panels produce electricity on cloudy days?

Yes, just less. Panels run on daylight, not direct sun, so they still generate under cloud, typically a fraction of their bright-sun output. This is why UK solar works despite the weather, and why the year is so summer-weighted: long, bright summer days produce far more than short, overcast winter ones. Across November to February, a UK system generates only around 10–15% of its annual total.

What reduces how much electricity a solar panel produces?

Shading is the biggest avoidable culprit, because shade on one panel can drag down a whole string. Beyond that: a north-facing or heavily east/west-split roof, a very flat or very steep pitch, high summer heat (panels lose a little efficiency when very hot), dirt build-up, and simply the season. Wattage sets the ceiling; the roof and the weather decide how close you get to it.

Related

• A homeowner's guide to going solar in the UK (2026)
• Solar in winter: what to expect
• Solar in summer: what to expect
• Smart Export Guarantee: how UK solar exports actually pay
• Is my roof suitable for solar?
• Estimate your savings