How much electricity does a 3 kW solar system generate in the UK?
3,277 kWh a year in London from a 3 kWp system, 9 kWh a day on average: 3 × 3.48 PVGIS sun hours × 0.86 after 14% losses. The year is lopsided: 406 kWh in July, 118 kWh in December. Across the UK cities in the table it runs from 2,712 kWh in Glasgow to 3,673 kWh in Brighton. Over a year that is 131% of what an Ofgem medium household uses (2,500 kWh).
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How much does a 3 kW system generate in each UK city?
Per day = 3 kWp × the city’s PVGIS sun hours × 0.86; per year = per day × 365; per month = per year / 12; the June and December columns use the PVGIS figure for that month times its days. The output calculator shows all twelve months for any of these cities and any size.
| City | Sun hours | kWh a day | kWh a month | kWh a year | June | December |
|---|---|---|---|---|---|---|
| London | 3.48 | 9 kWh | 273 kWh | 3,277 kWh | 393 kWh | 118 kWh |
| Brighton (South East) | 3.9 | 10.1 kWh | 306 kWh | 3,673 kWh | 459 kWh | 125 kWh |
| Plymouth (South West) | 3.7 | 9.5 kWh | 290 kWh | 3,484 kWh | 426 kWh | 114 kWh |
| Cardiff (Wales) | 3.47 | 9 kWh | 272 kWh | 3,268 kWh | 412 kWh | 105 kWh |
| Birmingham (West Midlands) | 3.27 | 8.4 kWh | 257 kWh | 3,079 kWh | 371 kWh | 109 kWh |
| Nottingham (East Midlands) | 3.3 | 8.5 kWh | 259 kWh | 3,108 kWh | 363 kWh | 110 kWh |
| Norwich (East of England) | 3.49 | 9 kWh | 274 kWh | 3,287 kWh | 391 kWh | 114 kWh |
| Manchester (North West) | 3 | 7.7 kWh | 235 kWh | 2,825 kWh | 350 kWh | 91 kWh |
| Leeds (Yorkshire) | 3.2 | 8.3 kWh | 251 kWh | 3,013 kWh | 351 kWh | 106 kWh |
| Newcastle (North East) | 3.18 | 8.2 kWh | 250 kWh | 2,995 kWh | 347 kWh | 98 kWh |
| Edinburgh (Scotland) | 3.07 | 7.9 kWh | 241 kWh | 2,891 kWh | 344 kWh | 78 kWh |
| Glasgow (Scotland) | 2.88 | 7.4 kWh | 226 kWh | 2,712 kWh | 348 kWh | 66 kWh |
| Aberdeen (Scotland) | 2.98 | 7.7 kWh | 234 kWh | 2,806 kWh | 354 kWh | 75 kWh |
| Belfast (Northern Ireland) | 3.09 | 8 kWh | 242 kWh | 2,910 kWh | 365 kWh | 88 kWh |
What does a 3 kW system make month by month?
Each month = 3 kWp × that month’s PVGIS sun hours × 0.86 × days in the month. London’s best month is July at 406 kWh and its worst December at 118 kWh.
| Month | London | Manchester | Edinburgh |
|---|---|---|---|
| January | 127 kWh | 85 kWh | 91 kWh |
| February | 165 kWh | 144 kWh | 155 kWh |
| March | 274 kWh | 247 kWh | 245 kWh |
| April | 365 kWh | 327 kWh | 332 kWh |
| May | 387 kWh | 362 kWh | 383 kWh |
| June | 393 kWh | 350 kWh | 344 kWh |
| July | 406 kWh | 352 kWh | 358 kWh |
| August | 359 kWh | 309 kWh | 323 kWh |
| September | 312 kWh | 261 kWh | 270 kWh |
| October | 217 kWh | 179 kWh | 184 kWh |
| November | 152 kWh | 122 kWh | 126 kWh |
| December | 118 kWh | 91 kWh | 78 kWh |
Is 3 kW enough for a UK home?
The London output against the three Ofgem household sizes: the share of the year’s use it equals, and the share of a December (the year’s use / 12) it covers. Above 100% the system makes more than the home uses over that period, which is exported unless a battery stores it.
| Household | kWh a year | Share of the year | Share of December |
|---|---|---|---|
| Low | 1,600 | 205% | 89% |
| Medium | 2,500 | 131% | 57% |
| High | 3,800 | 86% | 37% |
What the tables leave out
- Orientation and tilt: PVGIS figures are for the optimal slope facing south. An east or west roof gives less and shade from trees or chimneys less again; raise the losses in the calculator to see it.
- The kWh you keep: the yearly total is what the array makes, not what you use. The UK cost guide runs the cost, savings and payback.
- Other sizes: 4 kW in the UK and 5 kW in the UK.
- The other direction, from the kWh you use to the size you need: the power-a-house guide, the panel calculator and the pages for 1,000 kWh a month, 1,500 kWh a month, 2,000 kWh a month and 2,500 kWh a month.
Sources
UK sun hours, yearly and by month: European Commission Joint Research Centre, PVGIS 5.2, PVcalc for the city's coordinates at the optimal slope and azimuth. Panel: A 400 W panel is the middle of the Trina Vertex TSM-DE09 range and the common residential class in 2026; Trina Solar, Vertex TSM-DE09 data sheet, product range 390-405 W. Losses: NREL, PVWatts Version 5 Manual, section 11 System Losses, Table 6. Household use: Ofgem, "Review of typical domestic consumption values: decision", Table 1, electricity Profile Class 1, 2026 TDCV. Cost: Energy Saving Trust, "Solar panels". All read 2026-09-20; the full text of each source, with links, is under the calculator when you switch it to UK.
Frequently asked questions
- How many kWh does a 3 kW solar system produce per day in the UK?
- 9 kWh a day averaged over the year in London (3 kW × 3.48 × 0.86), 7.4 kWh in Glasgow, 10.1 kWh in Brighton. A June day in London gives about 13.1 kWh and a December day about 3.8 kWh.
- How much does a 3 kW solar system generate per year in the UK?
- 3,277 kWh in London, from the PVGIS 2005-2020 irradiation at the optimal tilt with 14% losses: per day × 365. The city table below gives the figure for 14 UK cities, from 2,712 kWh to 3,673 kWh.
- Is 3 kW of solar enough to power a house in the UK?
- Over the year the London output equals 205% of an Ofgem low household (1,600 kWh), 131% of a medium one (2,500 kWh) and 86% of a high one (3,800 kWh). In December it covers 57% of the medium household's month, and at night nothing, so a grid-tied home still buys electricity in winter and exports in summer.
- How many panels is a 3 kW system?
- 3 kWp is 7.5 panels' worth of 400 W; rounded up, 8 panels make 3.2 kWp, on about 15.4 m² of panel area (1.922 m² each). The 3.2 kWp array makes 3,496 kWh a year in London. The Energy Saving Trust's typical system is 4.5 kWp.
- How much does a 3 kW solar system cost in the UK?
- About £5,070 at £1,690 per kWp, the Energy Saving Trust price for a typical 4.5 kWp system scaled to 3 kWp. A quote for a different size, roof or brand will differ; the UK cost guide and the payback calculator add the savings and the payback time.
More guides
- How many kWh does a solar panel produce per day?
One 400 W panel per day, month and year at 3 to 6 sun hours, 1 to 12 kW systems, a panel and a 10 kW system in every US state, UK cities by month.
- How much electricity does a 4 kW solar system generate in the UK?
A 4 kW solar system produces about 4,369 kWh of electricity a year in London (12 kWh a day): 3,616 in Glasgow to 4,897 in Brighton. Month by month.
- How much electricity does a 5 kW solar system generate in the UK?
kWh a day, month and year from a 5 kWp system in every UK city, month by month in three cities (PVGIS), and against Ofgem household use.
- How many solar panels for 2,000 kWh a month?
2,000 kWh a month is 65.8 kWh a day: 43 panels of 400 W (17.2 kW) at 4.5 sun hours, about $44,720 installed. Every US state and UK city.
Last updated 2026-10-03. Estimates from published averages (NREL, EIA, Ofgem, industry cost surveys), each with its source and date: an installer's site survey and shading analysis replace them. Not financial advice.