Solar Panel Payback UK 2026: How Long to Break Even?
The short answer
- 10.8 to 12.6 years for a typical 4 kW system without a battery, depending on where you live
- About 21 years with a 5 kWh battery, because the battery has to be replaced before the system pays back
- About £7,100 net profit over 25 years for a 4 kW south facing system in southern England
A typical 4 kW solar panel system pays for itself in 10.8 to 12.6 years without a battery, depending on where you live, or about 21 years with a 5 kWh battery in southern England, because the battery has to be replaced along the way. After payback, the panels keep earning for the rest of a life of 25 years or more. The 0% VAT rate, which runs until 31 March 2027, takes about half a year off. Here is the full breakdown by scenario.
Get your exact payback period
Our solar panel calculator estimates your generation, savings, export income, and 25-year returns based on your roof direction, location, and electricity usage.
Payback summary
About 10.8 years for 4 kW in southern England. A £6,000 south facing system earns £556 a year; east or west roofs take 13.2 years and a battery stretches it to 20.7 years.
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| Scenario | Cost | Annual benefit | Payback |
|---|---|---|---|
| 4 kW, south, no battery, south England | £6,000 | £556 | 10.8 years |
| 4 kW, south, with battery, south England | £10,600, then £4,600 for a new battery | £735 | 20.7 years |
| 4 kW, south-east, no battery, south England | £6,000 | £534 | 11.2 years |
| 4 kW, south, no battery, north England | £6,000 | £505 | 11.9 years |
| 4 kW, south, no battery, Scotland | £6,000 | £477 | 12.6 years |
| 4 kW, east or west, no battery, south England | £6,000 | £454 | 13.2 years |
| 3 kW, south, no battery, south England | £4,750 | £434 | 10.9 years |
| 6 kW, south, no battery, south England | £9,250 | £794 | 11.6 years |
The data behind this table
Every row is what our solar calculator gives. Costs are the midpoints of our installed cost bands, at 0% VAT, checked against the government's solar PV cost data for April 2025 to March 2026. Payback is cost divided by the first year's benefit. Annual benefit includes bill savings at 26.32p per kWh and SEG export income (12p/kWh, the Outgoing Octopus rate). Self-use comes from the MCS MGD 003 look-up tables for a household that is out for about half the day and uses 2,500 kWh a year, so it falls as the array gets larger relative to the home. Battery cost is the Energy Saving Trust's £4,600 for 5 kWh; because a battery lasts about 10 to 12 years, the battery row counts a replacement, which falls due before the system has paid back. Generation from PVGIS. Get your personalised estimate.
Payback by region
From 10.8 years in southern England to 12.6 years in Scotland, for 4 kW south facing. Generation varies by roughly 15%, a gap of about 1.6 years, so solar works across Great Britain.
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Solar generation varies by roughly 16% across Great Britain. With a postcode, our calculator uses the PVGIS figure for your postcode district, less 7% for shading and dirt on real roofs. Without one it uses regional averages worked out the same way: about 945 kWh per kW a year for southern England, 885 kWh for the Midlands and Wales, 850 kWh for northern England and 795 kWh for Scotland. Northern Ireland is not covered, because the Smart Export Guarantee applies in Great Britain only and Northern Ireland has its own electricity prices.
For a 4 kW south facing system without a battery, this translates to payback periods of about 10.8 years in southern England, 11.4 years in the Midlands, 11.4 years in Wales, 11.9 years in northern England and 12.6 years in Scotland. The difference is about 1.8 years, not a dealbreaker. Solar panels are worth considering right across Great Britain. Each region has its own page, with a map, in solar payback by region.
Payback by roof direction
South is best, and east or west adds about 2.5 years. South-east and south-west add under a year (11.3 and 11.4 years), while north facing roofs push payback to about 17 to 18 years.
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Roof orientation matters more than most people expect. A south facing roof generates the maximum amount. PVGIS modelling for a 35 degree roof in London, Manchester and Edinburgh puts south-east at about 95% of a south facing roof and south-west at about 93%, adding under a year to payback (11.3 and 11.4 years). East or west facing roofs produce about 80%, adding about 2.5 years (13.2 years). A flat roof with panels tilted up at about 10 degrees produces about 90%, for a payback of 11.8 years.
North facing roofs are generally not recommended. At a 35 degree pitch they produce only about 53% to 57% of a south facing roof, which on our figures pushes payback for a 4 kW system in southern England to about 17 to 18 years. If your only available roof space faces north, the financial case is weak.
With and without a battery
A battery makes payback longer, not shorter. A £4,600 battery adds about £180 a year, so a 4 kW system goes from 10.8 years to 20.7 years once the replacement battery is counted.
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This is the most common question, and the answer is counterintuitive. A battery makes your payback period longer, not shorter. The Energy Saving Trust prices a 5 kWh battery at around £4,600. It increases your annual savings because you use more of your own solar electricity instead of exporting it cheaply, but not by enough to cover its cost.
Without a battery, a 4 kW array on an average home self-uses about 19% of generation (valued at 26.32p/kWh) and exports the rest (valued at 12p/kWh). A 5 kWh battery lifts self-use to about 52%. Bill savings rise by about £330 a year, but export income falls by about £150, so the total annual benefit gains about £180.
At £180 a year, the battery on its own takes about 26 years to repay its £4,600, and the Energy Saving Trust expects it to last about 10 to 12 years. It has to be replaced before the combined system has paid back, so payback for a 4 kW system in southern England goes from 10.8 years to 20.7 years once the second battery is counted. Over 25 years the net return is about £2,100 with a battery against about £7,100 without. A battery can still make sense for other reasons, and it pairs well with time of use tariffs; our solar battery guide covers when it does.
Payback by system size
For a medium user, 4 kW pays back fastest, at 10.8 years. Payback stays close to 11 years from 3 kW to 5 kW and is 11.6 years at 6 kW; heat pump or EV homes can justify more.
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Cost per kW falls only slightly with size. The government's solar PV cost data for April 2025 to March 2026 puts the median at £1,595 per kW for systems up to 4 kW and £1,546 per kW for 4 to 10 kW. Meanwhile a larger system exports a bigger share of its output at the lower export rate, so for a medium user the payback stays close to 11 years from 3 kW (10.9 years) to 5 kW (11.1 years) and is a little longer at 6 kW (11.6 years).
For a medium user, 4 kW has the shortest payback in our figures, at 10.8 years. It generates about 3,780 kWh a year in southern England, around 1.5 times Ofgem's typical medium use of 2,500 kWh. If you have a heat pump or electric vehicle, a larger 5 to 6 kW system can make sense because your electricity use is higher and you use a greater share of the generation yourself.
25-year profit projection
About £7,200 net profit over 25 years without a battery, or about £2,200 with one. That is for 4 kW south facing in southern England, before replacing the inverter after around 12 years.
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Solar panels should last 25 years or more, according to the Energy Saving Trust, and our calculator assumes their output falls by 0.5% a year. Over 25 years at today's prices, a 4 kW south facing system in southern England without a battery returns about £7,200 net profit: total benefits of £13,200 minus the £6,000 cost. With a battery, net profit is about £2,200: total benefits of £17,400 minus £15,200 for the panels, the battery and one replacement battery. Neither figure includes replacing the inverter, which the Energy Saving Trust expects after around 12 years.
What speeds up payback
A better export tariff, more daytime use, a south roof and 0% VAT. On a 17.5p export rate a 4 kW system pays back in 8.3 years, against 10.8 years at 12p.
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Higher electricity consumption. If you use more electricity during daylight hours (home workers, heat pump owners, EV chargers), you self-use a larger proportion at the full 26.32p rate. This increases annual savings and shortens payback.
South-facing roof in southern England. Maximum generation, shortest payback.
A better export tariff. The same 4 kW system in southern England pays back in 8.3 years on a 17.5p export rate and 19 years on a 4.1p one, against 10.8 years at 12p. The 17.5p rate we found on 25 September 2026 is only for systems E.ON installed, so compare what is open to you before you sign.
Higher electricity prices. If electricity prices rise, your savings rise with them. Every 1p increase in the electricity rate adds roughly £7 a year to the savings from a 4 kW system without a battery, or £20 with one.
0% VAT. Installing before 31 March 2027, while the 0% rate applies, avoids the 5% rate that returns on 1 April 2027. That is about £300 on a £6,000 system, which shortens payback by about half a year.
What slows down payback
Low self-use, a north facing or shaded roof and lower electricity prices. Exported power earns 12p instead of saving 26.32p, and each 1p fall in the unit rate takes about £7 a year off.
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Low self-use. If you are out all day and use most electricity in the evening, you export most of your generation at 12p instead of using it at 26.32p. A battery or smart scheduling fixes this.
North-facing or heavily shaded roof. Reduces generation and extends payback beyond the point of good financial return.
Lower electricity prices. Savings move with the unit rate: every 1p fall takes about £7 a year off a 4 kW system without a battery. Our figures use the Ofgem price cap for October to December 2026 throughout and do not forecast future prices.
Frequently asked questions
How long do solar panels take to pay for themselves in the UK?
About 10.8 to 12.6 years for a 4 kW system with no battery and a south facing roof, depending on where you live, and about 21 years with a 5 kWh battery once its replacement is counted. South facing roofs in southern England pay back fastest.
What is the payback on a 4 kW solar system in the UK?
A 4 kW system costs £5,000 to £7,000, midpoint £6,000, and brings in £477 to £556 a year in bill savings plus Smart Export Guarantee income, depending on region. Payback is 10.8 to 12.6 years without a battery. Over 25 years, net profit in southern England is about £7,100 before an inverter replacement.
Do solar panels pay for themselves faster with a battery?
No. A 5 kWh battery costs about £4,600 and adds about £180 a year, as bill savings rise by about £330 while export income falls by about £150. It lasts 10 to 12 years, so it is replaced before the system pays back, and payback for a 4 kW system in southern England goes from 10.8 years to 20.7 years.
Are solar panels worth it in northern England or Scotland?
Yes, but payback is about 1 to 2 years longer than in southern England: 11.9 years in northern England and 12.6 years in Scotland for 4 kW. A 4 kW system in Scotland generates about 16% less than in the south (3,180 kWh against 3,780 kWh a year).
Does roof direction affect solar panel payback?
Yes. South facing roofs generate the most and pay back fastest. East or west facing roofs generate about 20% less, adding about 2.5 years to payback. South-east and south-west are nearly as good as due south. North facing roofs are generally not recommended.
Data sources
PVGIS, MCS, Ofgem and the Energy Saving Trust. Export rates come from Octopus Energy and E.ON Next, checked 25 September 2026, and installed costs from DESNZ solar PV cost data.
Show every source
Generation data from PVGIS (EU JRC). Self-use from MCS MGD 003. Electricity rates from Ofgem, October to December 2026. Export rates from Octopus Energy and E.ON Next, checked 25 September 2026; scheme rules from Ofgem SEG. Installed costs checked against the DESNZ solar PV cost data, May 2026. Battery cost and lifespan, panel and inverter life from the Energy Saving Trust. See our full methodology.