Estimates only. In the UK, use an MCS certified installer, and have the electrical work done by a qualified electrician to BS 7671. The installer notifies the network operator under G98 or G99.
Formula and breakdown
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This solar panel cost calculator estimates what a home solar system will cost to install in the UK, line by line: the panels, inverter and fitting priced per kWp, scaffolding and extras, an optional battery, and VAT at the correct rate for the date you buy. Readers in Ireland and the rest of Europe can switch to euros and enter local prices.
Quick answer: The Energy Saving Trust puts an average UK home solar panel system at around £7,600 for about 4.5 kWp, roughly £1,690 per kWp. A solar panel cost calculator adds scaffolding, extras and an optional battery, which EST prices at £5,000 to £8,000, then applies VAT, which is 0% for UK homes until 31 March 2027.
What Is a Solar Panel Cost Calculator?
A solar panel cost calculator is a tool that builds an installed price for a solar PV system from its size and the separate items an installer charges for. The formula in plain words: system size in kWp times the price per kWp, plus fixed items such as scaffolding and extras, plus any battery, gives the price before VAT; add VAT at the rate that applies to you to get the total.
The solar panel cost calculator also divides the solar part of the bill by the system size to give an all-in cost per kWp, which is the fairest way to compare quotes for systems of different sizes. Finally, it spreads that cost over the energy the panels should produce in their life to show a simple cost per kWh.
How Do You Use the Solar Panel Cost Calculator?
- Enter the system size in kWp. If you do not know it yet, our solar panel sizing calculator works it out from your yearly electricity use.
- Enter the price per kWp for panels, inverter and fitting before VAT. The default is an example based on the Energy Saving Trust average; replace it with the figure from a quote.
- Add scaffolding and any extras, such as bird mesh, optimisers or a monitoring upgrade. Enter 0 for anything already in the main price.
- Choose whether to add a battery and enter its installed price.
- Set the VAT rate, or tap a shortcut: 0% for UK homes until 31 March 2027, 5% from April 2027, or 20% standard.
- Enter the panel wattage, an expected yearly output per kWp and the years you expect to use the system.
- If you have a quote, enter its total to see how it compares with the estimate. Open the breakdown to check each step.
How Much Do Solar Panels Cost in the UK in 2026?
An average home solar panel system costs around £7,600 to install, according to the Energy Saving Trust advice on solar panels, last updated on 1 October 2026. The same page says a typical domestic system is around 4.5 kWp, covers 20 to 30 square metres of roof and uses about 12 panels. Dividing the cost by the size gives roughly £1,690 per kWp, which is the example default in the solar panel cost calculator.
Treat that figure as a starting point rather than a price list. Roof height, access, the panel and inverter brand, distance to the consumer unit and local labour costs all move the price. The government also publishes yearly solar PV cost data from certified installations if you want to check how prices have moved over time.
Why Does a Small Solar System Cost More per kWp?
A small system costs more per kWp because fixed costs such as scaffolding, design and connection stay about the same while the number of kilowatts falls. The table uses the example defaults of £1,690 per kWp and an £800 scaffold at 0% VAT, with 900 kWh per kWp a year over 25 years.
| System size | Total cost | All-in cost per kWp | Lifetime cost per kWh |
|---|---|---|---|
| 2 kWp | £4,180 | £2,090 | 9.3p |
| 3 kWp | £5,870 | £1,957 | 8.7p |
| 4 kWp | £7,560 | £1,890 | 8.4p |
| 4.5 kWp | £8,405 | £1,868 | 8.3p |
| 6 kWp | £10,940 | £1,823 | 8.1p |
| 8 kWp | £14,320 | £1,790 | 8.0p |
The pattern matters when your roof could take more panels: filling it often lowers the cost of each kWh, even though the total bill is higher. Whether the extra output pays back depends on how much you use and export, which our solar payback calculator works out year by year.
Do You Pay VAT on Solar Panels and Batteries?
No VAT is charged on solar panels installed in UK homes between 1 May 2023 and 31 March 2027, because HMRC VAT Notice 708/6 zero rates them as energy-saving materials. After that date the relief is due to revert to the reduced rate of 5%. Since 1 February 2024 the zero rate has also covered batteries installed in homes, including a battery added to existing panels and a standalone battery charged from the grid.
The zero rate applies to the installation in residential accommodation, so a business roof or a kit you buy and fit yourself may be charged at 20%. In Ireland and the rest of Europe, enter your own national rate in the VAT field.
How Much Does a Battery Add to the Cost of Solar Panels?
A home battery adds around £5,000 to £8,000, according to the Energy Saving Trust. The solar panel cost calculator keeps the battery as a separate line and leaves it out of the cost per kWp and cost per kWh, so you can see what the panels cost on their own. To decide what capacity you need before asking for prices, use the solar battery size calculator.
How Do You Check a Solar Panel Quote?
Divide the quote total by the system size and compare the result with about £1,870 per kWp for a 4.5 kWp system using the example defaults; a quote well above or below deserves a closer look. Enter the total in the quote field and the solar panel cost calculator shows the gap as a percentage. Then check the details that change the value of a quote:
- Panel and inverter models, with datasheets and warranty terms.
- Whether scaffolding, bird mesh, an isolator and monitoring are included.
- That the installer is MCS certified, which is required for most export tariffs.
- That the installer will notify the network operator under G98, or apply under G99 for larger systems.
- The expected yearly generation and how it was worked out.
Solar installation includes roof work and mains electrics. The wiring must be done or checked by a qualified electrician and, in the UK, meet BS 7671. If your roof is old or you are adding a heavy battery, ask whether a structural check is needed.
Worked Example: A 4.5 kWp System With a Battery
Example: a semi-detached house in Leeds is quoted for a 4.5 kWp system with a battery, totalling £15,000 including VAT, to be fitted in November 2026.
- Solar: 4.5 kWp x £1,690 = £7,605.
- Scaffolding at an example £800 and no extras gives £800 of fixed items.
- Battery at the lower end of the EST range: £5,000.
- Before VAT: £7,605 + £800 + £5,000 = £13,405. VAT at 0% = £0. Estimate: £13,405.
- The quote of £15,000 is about 12% above the estimate, so it is worth asking what is included and whether the battery is a larger model.
- Solar cost per kWp: £8,405 / 4.5 = £1,868. Over 25 years at 900 kWh per kWp, the panels produce 101,250 kWh, so they cost about 8.3p per kWh.
If the same job slipped to April 2027 and the 5% rate applied, the estimate would rise by £670 to £14,075. For the yield, the free PVGIS tool from the EU Joint Research Centre gives a figure for your own roof.
Frequently Asked Questions
How much does a 4 kWp solar system cost in the UK?
Using the Energy Saving Trust average of about £7,600 for 4.5 kWp, a 4 kWp system works out at roughly £6,760 for the panels and fitting, plus scaffolding. With an example £800 scaffold the total is about £7,560 at the current 0% VAT rate.
Do solar panels have VAT in the UK?
Installing solar panels in a home is zero rated for VAT from 1 May 2023 to 31 March 2027 under HMRC Notice 708/6. After that date the relief is due to return to the reduced rate of 5%. Batteries fitted in homes have been included since 1 February 2024.
Why do small solar systems cost more per kWp?
Scaffolding, design, electrical connection and paperwork cost much the same whether you fit 5 panels or 15. Those fixed costs are spread over fewer kilowatts on a small system, so the price per kWp rises. The calculator shows this as the all-in cost per kWp.
How much does a solar battery add to the cost?
The Energy Saving Trust says battery storage tends to cost around £5,000 to £8,000. Fitting it at the same time as the panels can save a second visit and some electrical work. Enter the battery price from your quote to see the combined total.
Is scaffolding included in a solar panel quote?
Many quotes include scaffolding, but some list it separately or exclude it for awkward roofs. Check the quote wording. If it is already in your per kWp price, set the scaffolding field to 0 so the calculator does not count it twice.
How can I tell if a solar quote is fair?
Divide the quote total by the system size in kWp and compare it with the benchmark. Enter the quote in the calculator to see the percentage gap. Then check what is included, such as panel and inverter models, warranties, scaffolding, MCS certification and any battery.
Checked October 2026 by the Solaxyra Editorial Team. Sources: Energy Saving Trust, solar panels, HMRC VAT Notice 708/6, DESNZ solar PV cost data, PVGIS, EU JRC.