The Short Answer
If you have a decent south, east or west-facing roof and you're staying put, we think it's worth doing, and worth doing before VAT goes to 5% on 1 April 2027. Get at least two quotes, sign up for an export tariff, and leave the battery unless you're on (or moving to) a time-of-use tariff.
A 4kW system costs about £6,200 to £6,600 fitted, and there's no VAT on solar panels fitted to homes anywhere in the UK until 31 March 2027. On our estimate for a south-facing roof in central England, it's worth about £599 a year, so it pays back in about 10 to 11 years (the Energy Saving Trust says 9 to 12 years, depending on where you live). A battery adds £5,000 to £8,000 and, on our figures, doesn't pay for itself on a standard tariff.
How Much Do Solar Panels Cost?
Here's what installs cost in 2025/26, from DESNZ's figures for Great Britain:
| System | Fitted cost | Generation a year (our estimate) |
|---|---|---|
| 3kW | £4,800 to £5,900 | 2,850 kWh |
| 4kW | £6,200 to £6,600 | 3,800 kWh |
| 5kW | £7,700 to £8,200 | 4,750 kWh |
| 6kW | £9,300 to £9,900 | 5,700 kWh |
How we got these: DESNZ publishes what MCS-certified installs actually cost, from the MCS database. Homes paid a mean of £1,955 per kW for systems under 4kW and £1,645 per kW from 4 to 10kW (a 4kW system counts in the 4 to 10kW band). The medians across all installs, homes and other buildings, were £1,595 and £1,546. We take the median as the low end and the home mean as the high end.
Bigger systems cost less per kW. The Energy Saving Trust's £7,600 for 4.5kWp agrees with DESNZ's home mean, which gives about £7,400. It says a 4.5kWp system typically takes 20 to 30 square metres of roof and around 12 panels.
Estimate Your System
Pick a size and whether you want a battery:
1. What size system?
The Energy Saving Trust says the average home system is around 4.5 kWp, on 20 to 30 square metres of roof. Bigger systems need more roof area.
2. Panel type
Solar tiles look tidier but cost more: the Energy Saving Trust says they normally cost about 1.5 times as much as panels, which is what we use.
3. Battery storage
A battery stores spare daytime solar to use later, lifting the share you use at home from 26% to 42% with 5 kWh or 56% with 10 kWh, for this size in a home using Ofgem's typical 2,500 kWh a year.
Estimated installed cost
£6,200 to £6,600
Panels from DESNZ's figures for 2025/26 MCS installs: the median of all installs to the mean for homes, covering the equipment, fitting, connection and VAT (0% on solar until 31 March 2027).
Cost breakdown
- Solar panels + installation
- £6,200 to £6,600
- Battery storage
- None
- Total (0% VAT)
- £6,200 to £6,600
Bill savings
£263 / year
999 kWh self-used at 26.32p
SEG export income
£336 / year
2,801 kWh exported at 12p
Total annual benefit
£599 / year
Payback period
10.4-11.0 years
25-year net profit
+£7,776
Want a real quote for your home?
These are estimates. Get free quotes from MCS-certified installers to see exact costs for your roof. Takes about 60 seconds, no obligation.
Based on the Ofgem price cap for 1 October to 31 December 2026 (26.32p/kWh) and Octopus Outgoing SEG rate (12p/kWh), on our estimate of 950 kWh a year per kW for a south-facing roof in central England, with the share used at home from BRE's SAP 10.2 self-use formula for this size in a home using Ofgem's typical 2,500 kWh a year (26% without a battery, 56% with 10 kWh, taking 80% of a battery as usable, our assumption). For the 10 kWh battery we use the Energy Saving Trust's £5,000 to £8,000 for battery storage, which gives no size; solar tiles at about 1.5 times the panel price are its ratio too, and the 5 kWh battery's price is our estimate. The 25-year figure holds prices flat, uses the middle of the cost range and deducts one replacement inverter at £800, the Energy Saving Trust's figure (it says inverters typically need replacing every 10 to 15 years, so you may need two). For a region- and orientation-aware estimate, use our full solar ROI calculator.
What the Price Covers
DESNZ's figures cover the panels and other generating equipment, installing them, connecting them to the electricity supply, and VAT where it applies. They don't include a battery, extended warranties or other work done at the same time. According to the Energy Saving Trust, what makes one quote dearer than another is the size of the system, how hard your roof is to reach, panels against solar tiles, building them into the roof, and whether the roof needs re-covering. It says you can save on installation if scaffolding is already up for roof work.
Prices Fell Last Year
DESNZ says that after adjusting for inflation, the median cost per kW fell by 7% for installs under 4kW and 9% for 4 to 10kW between 2024/25 and 2025/26, a year with the highest number of installations on record. Its figures are for Great Britain; MCS installs in Northern Ireland aren't included.
0% VAT Until March 2027
If you're going ahead anyway, we'd get it fitted before April, not just ordered. Installing solar panels in a home is zero-rated for VAT until 31 March 2027, and so is a battery, whether it's fitted with the panels or added later. From 1 April 2027 the rate goes to 5%, which would add about £310 to £330 to a 4kW system at today's prices.
What You Get Back
Solar pays you two ways: the electricity you use yourself instead of buying it at 26.32p a kWh, and the electricity you export, at 12p on Octopus's Outgoing tariff. That's a variable rate, and only for Octopus supply customers on certain import tariffs; other suppliers pay their own rates. So each kWh you use at home is worth 14.32p more than one you export.
Our estimate assumes 950 kWh a year per kW, at Ofgem's 1 October to 31 December 2026 cap rate for England, Scotland and Wales, with prices held flat. Ofgem says that rate carries no VAT from 1 October 2026 to 31 March 2027. The share you use at home comes from the government's SAP 10.2 self-use formula for each size, in a home using Ofgem's typical 2,500 kWh a year: 26% at 4kW, and a smaller share for bigger systems. Here's what that gives:
| System | Saving on bills | Export income | Total a year | Payback |
|---|---|---|---|---|
| 3kW | £236 | £235 | £471 | 10 to 13 years |
| 4kW | £263 | £336 | £599 | 10 to 11 years |
| 5kW | £281 | £442 | £723 | 11 years |
| 6kW | £293 | £550 | £843 | 11 to 12 years |
The Energy Saving Trust's own figures, for a four-bedroom detached house at July 2026 prices, with export payments:
| Where | Saving a year (home all day to out all day) | Payback |
|---|---|---|
| London | £900 to £930 | 9 years |
| Manchester | £740 to £810 | 10 to 11 years |
| Aberystwyth | £840 to £870 | 9 to 10 years |
| Stirling | £680 to £740 | 11 to 12 years |
Without export payments its savings fall to about £200 to £330 in London, which is why we'd always sign up for an export tariff. In Belfast it puts the saving at £370 to £570 a year (an oil-heated home, November 2025 prices).
How Much a Year Can Vary
Our 950 kWh per kW is our estimate for a south-facing roof in central England; further north, or facing east or west, expect less. Across all UK solar, DESNZ's figures work out at an average of about 927 kWh per kW a year from 2016 to 2025, from about 808 in 2024 to 981 in 2018. The worst of those years made about 18% less than the best. Our solar ROI calculator takes your region and roof direction.
Adding a Battery
The case for a battery rests on a time-of-use tariff, where it can charge cheaply overnight. The Energy Saving Trust says battery storage tends to cost around £5,000 to £8,000. On the government's SAP 10.2 self-use formula, a 10 kWh battery (8 kWh usable, our assumption) on a 4kW system lifts the share you use at home from 26% to 56%, in a home using Ofgem's typical 2,500 kWh a year. On a standard tariff that's worth only about £163 a year, because each kWh it keeps is worth just 14.32p more than exporting it, so it would take 31 to 49 years to repay the battery. Our battery storage guide runs the time-of-use numbers.
Getting Paid for What You Export
Under the Smart Export Guarantee, suppliers pay you for electricity you send to the grid. Ofgem says suppliers set their own rates, which must always be above zero, and installations must be in Great Britain. Octopus pays 12p a kWh on Outgoing Octopus, and on Prime Outgoing 16p from 4pm to 7pm and 9p the rest of the day. The Energy Saving Trust says that in Northern Ireland you should ask your supplier whether it offers an export tariff.
What to Ask an Installer
Quotes are only comparable if they say the same things. We'd ask every installer:
- What size system, in kW, and which panels and inverter? Price per kW is the fairest comparison, and bigger systems should cost less per kW.
- How much will it generate a year? Compare their estimate with ours (950 kWh per kW on a south-facing roof in central England) and ask why if it's much higher.
- Is scaffolding included? Roof access is one of the things the Energy Saving Trust says makes a quote dearer. If you're having roof work done, ask whether they can use the same scaffolding.
- What's included beyond the panels: the connection to your electricity supply, a battery or not, any extended warranty.
- Who to sign up with for export payments, and what you'll need from them to do it.
The Mistakes to Avoid
- Buying a battery on a standard tariff. On our figures it takes 31 to 49 years to repay itself; the case for one rests on cheap overnight charging.
- Not signing up for an export tariff. It's the difference between the Energy Saving Trust's with- and without-export savings above, every year.
- Leaving it until after 31 March 2027. VAT goes to 5%, about £310 to £330 more on a 4kW system.
- Comparing totals, not price per kW. A cheaper quote for a smaller system isn't cheaper.
- Forgetting the inverter. Budget for at least one replacement over the panels' life (below).
Upkeep and Replacement Parts
The Energy Saving Trust says panels should last 25 years or more, but an inverter needs replacing after around 12 years; its maintenance page says every 10 to 15 years, usually costing around £800. The calculator above takes one replacement off its 25-year figure; over 25 years you may need two.
Get real solar costs for your home
Every roof is different. Get personalised quotes from MCS-certified installers to see what solar will actually cost you. Free, no obligation.
Where to Go Next
- Solar panel grants: who can get panels paid for.
- Solar battery storage: when a battery pays.
- Solar ROI calculator: your region and roof.
- Are solar panels worth it? A verdict for your roof.
- How many solar panels you need, by home and usage.
- How to pay for solar panels: cash, loans and finance.
- VAT on solar panels: what 0% covers.
- Solar with a heat pump: what they're worth together.
Frequently Asked Questions
Protect and Maintain Your Solar Investment
These accessories help you keep your panels performing at their best for decades.
Solar Panel Cleaning Kit with Extension Pole
£42.57A soft brush on a telescopic pole, for rinsing panels you can reach safely from the ground. Most rooftop panels are cleaned well enough by rain.
6m telescopic poleFind on Amazon
Solar Panel Bird Proofing Mesh Kit (30m)
Check priceMesh that clips around the edge of the panels to stop birds nesting underneath. Best fitted by an installer, since it means working at height.
30m roll + 60 clipsFind on AmazonAs an Amazon Associate we earn from qualifying purchases. Prices and stock are checked against Amazon every few hours and may have changed since.
