A typical 4 kW solar system on a London home costs £5,000 to £8,000 installed, at 0% VAT until 31 March 2027. A small 2 to 3 kW system is around £4,000 to £5,500 and a 6 kW system £7,500 to £11,000. Those are indicative 2026 market ranges. Scaffold, the roof type, bird mesh, the inverter and whether you add a battery are what move an individual quote inside or outside them.
Key takeaways
- Typical installed price for a 4 kW system (10 to 12 panels) in London: £5,000 to £8,000.
- Solar panels are an energy-saving material, so installation is 0% VAT until 31 March 2027, then 5%.
- A south facing 4 kW system in London generates around 3,400 to 3,800 kWh a year.
- Export payments under the Smart Export Guarantee are 5p to 15p per kWh; a typical 4 kW system earns £150 to £400 a year.
- Payback is typically 7 to 12 years, shorter with high daytime use or a battery.
- Solar at Stay Warm is arranged and project-managed by us and installed by accredited, MCS certified installers.
How much do solar panels cost in London?
Prices below are indicative 2026 ranges for a standard pitched roof in London and the South-East. They include panels, inverter, mounting, electrical work, scaffold, MCS certification and DNO notification. They exclude a battery unless stated. A modern panel produces around 400 to 450 W, so system size is mainly a count of panels.
| System size | Panels | Typical installed price | Suits |
|---|---|---|---|
| 2 to 3 kW | 6 to 8 | £4,000 to £5,500 | Small roofs, flats, terraces with one usable pitch |
| 4 kW | 10 to 12 | £5,000 to £8,000 | Most 3 bed semis and terraces |
| 6 kW | 14 to 16 | £7,500 to £11,000 | Larger roofs, EV or heat pump households |
| Add a 5 to 10 kWh battery | n/a | £3,000 to £7,000 | Fitted at the same time, also 0% VAT |
The price per kW falls as the system gets bigger, because the scaffold, the inverter, the electrician and the paperwork cost about the same whether you fit 8 panels or 14. That is why a 6 kW system is nowhere near 50% more than a 4 kW one.
What pushes a solar quote up or down
- Scaffold. A two storey semi needs one lift of scaffold. A terrace with no side access, a three storey house or a rear roof over a conservatory needs more, which can add several hundred pounds. If we are already insulating the walls or the loft, the same scaffold serves both jobs.
- Roof type. Plain clay tiles and slates take longer to hook and flash than interlocking concrete tiles. A flat roof needs tilted frames and ballast, which costs more per panel.
- Bird mesh. Pigeons nest under panels on London roofs. Mesh clipped around the array is a modest extra and far cheaper than removing a nest later.
- Inverter. A string inverter is the standard. A hybrid inverter that can also run a battery costs more up front but avoids a second unit if you add storage later. Optimisers on each panel help a shaded roof and add to the price.
- Battery. A 5 kWh battery adds about £3,000 to £4,500, a 10 kWh battery £4,500 to £7,000. It is the biggest optional item; see is a home battery worth it.
- Electrical work. An old consumer unit or a long cable run from the roof to the fuse board adds labour.
What a London roof actually generates
A south facing 4 kW system in London generates around 3,400 to 3,800 kWh a year. An east or west facing roof gives roughly 15 to 20% less. A north facing roof is usually not worth panelling. Shading from a chimney, a neighbour's roof or a tree cuts output more than most people expect.
What you save depends on how much of that power you use in the house instead of exporting it. A household out all day might use only a third of what the panels make; one working from home, running a heat pump or charging a car uses far more. The rest is exported and paid under the Smart Export Guarantee at 5p to 15p per kWh, depending on the supplier.
| 4 kW system, 3,600 kWh a year | Used in the home | Exported | Indicative annual value |
|---|---|---|---|
| Low daytime use, no battery | about 1,100 kWh | about 2,500 kWh | £400 to £550 |
| High daytime use, no battery | about 1,800 kWh | about 1,800 kWh | £550 to £700 |
| Any household with a battery | about 2,500 kWh | about 1,100 kWh | £700 to £850 |
The table assumes an import price of around 25p per kWh and an export price of around 10p per kWh, used for illustration only. Your own tariff, and whether you move washing, dishwashing and charging into daylight hours, decide which row you sit in.
How long until solar panels pay for themselves?
Divide the installed price by the annual value. A £6,500 system worth £550 a year pays back in about 12 years. The same system in a house that uses most of its own power, worth £750 a year, pays back in under 9 years. That is where the typical 7 to 12 year range comes from. Panels are usually warranted for 25 years of output, so the years after payback are the return.
A battery lengthens the simple payback because it adds cost, but it raises the share of solar power you use and lets you buy cheap off-peak electricity on a time of use tariff. Whether that is worth it for you is a separate calculation, covered in are solar panels worth it.
Is there any help with the cost?
Three things, none of them a cash grant for most homeowners. First, the installation is 0% VAT until 31 March 2027 as an energy-saving material, then 5%. Second, the Smart Export Guarantee pays you for what you export, and an MCS certificate is what qualifies you for it. Third, the Warm Homes: Local Grant funds solar and batteries for owner occupiers on a low income in an EPC D to G home until March 2028, but the council appoints the installer, so that is a route through your council rather than through us.
Anything advertised as "free solar panels" in 2026 is either a lease on your roof or a mis-sold loan. The solar panel grants guide explains what exists and what to avoid.
How Stay Warm quotes solar
We are an insulation company first, with 500+ installations and a 9.87/10 Checkatrade rating from 122 reviews. Solar is arranged and project-managed by Stay Warm and installed by accredited, MCS certified installers. You deal with one surveyor, one written quote and one point of contact.
- Free survey: roof orientation, pitch, shading, tile type and the fuse board.
- A fixed written quote with the system size, scaffold, bird mesh and any battery as separate lines.
- Installation by the MCS certified installer, usually one to two days on site.
- MCS certificate and DNO notification, which is what you need to sign up for an export tariff.
Check the fabric before any solar quote. A well insulated home needs less energy and a smaller system. If the loft is thin or the walls are solid and bare, book a free heat loss survey and we will price the insulation and the solar together. Full details are on the solar panels service page.
Frequently asked questions
How much does a 4 kW solar system cost in London?
Typically £5,000 to £8,000 installed in 2026, including scaffold, inverter, electrical work and MCS certification, at 0% VAT. Bird mesh, a hybrid inverter or a battery are added on top and should appear as separate lines on the quote.
Do solar panels cost more in London than elsewhere?
Labour and scaffold cost more in London, and terraced streets often need more scaffold because there is no side access. The panels and inverter cost the same. The difference is usually a few hundred pounds, not thousands.
Is VAT charged on solar panels?
No. Solar panels and batteries fitted in a home are energy-saving materials under HMRC VAT Notice 708/6, so the installation is 0% VAT until 31 March 2027. After that date the rate is due to become 5%.
How much do solar panels save per year?
For a 4 kW system in London, an indicative £400 to £850 a year in avoided electricity and export payments, depending on how much of the power you use at home. The Smart Export Guarantee alone is typically £150 to £400 a year.
Who installs the panels if I book through Stay Warm?
An accredited, MCS certified installer. Stay Warm surveys, quotes, arranges and project-manages the work, and the MCS certificate is what allows you to claim an export tariff. Where we are also insulating the walls, one scaffold serves both jobs.