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Cost of Solar Panels Calculator (UK)

Free UK solar panel cost calculator. Estimate installed cost from your monthly kWh, peak sun hours, £/W price, and the 0% VAT relief. 2026 MCS, Energy Saving Trust and Solar Energy UK data.

Cost of Solar Panels Calculator

System size
3.89 kW
Gross cost
£6,031
Net cost after incentive
£6,031
Typical range
£5,126 – £6,935
Near UK median (£1.55/W)
Cost per kW: £1,550/kW

How to use this calculator

The calculator turns your real electricity usage into a kWp system size, then prices it at UK market rates. Five inputs:

  1. Monthly electricity use (kWh) — pull your last 12 months from your energy supplier’s online dashboard. The 2026 Ofgem typical-domestic-consumption value (TDCV) is 2,700 kWh/year for medium users (about 225 kWh/month) and 4,100 kWh/year for high users (about 340 kWh/month). Heat pump? Add 250 to 400 kWh/month in winter. EV? Add 200 to 300 kWh/month.
  2. Target offset (%) — 100% means a system sized to match your annual consumption. Most UK homes with SEG should target 80 to 100%; oversizing past 100% rarely pays back because Octopus Outgoing Fixed (15p/kWh) is well below import rates. With a battery and time-of-use tariff (Octopus Flux, Cosy), 100 to 120% can be cost-effective.
  3. Peak sun hours/day — UK annual average ranges from 2.4 (Scotland) to 3.0 (south coast), with 2.6 being the England average. Met Office and PVGIS-SARAH3 data are the references; the Energy Saving Trust uses 2.7 as its 4 kWp benchmark for England and Wales.
  4. Installed cost per watt — the all-in MCS turnkey price including 0% VAT. The 2026 Solar Energy UK median is £1.55/W for systems 3 to 5 kWp, dropping to £1.35/W at 8 to 10 kWp. Use the actual MCS quote when you have one.
  5. Grant / 0% VAT (%) — leave at 0 since VAT relief is already baked into the MCS quote price. Use this field if you qualify for ECO4 (which can cover 100%), Home Upgrade Grant, or local authority grants.

How the math works

The calculator sizes your system from annual kWh and peak sun hours:

annual_target_kWh = monthly_kWh × 12 × (offset% / 100)
system_kWp        = annual_target_kWh / (peak_sun_hours × 365 × 0.78)
gross_cost        = system_kWp × 1000 × £/W
range_low/high    = gross_cost × 0.85 / 1.15

The 0.78 derate factor matches MCS MIS 3002 calculation methodology (4-6% inverter loss, 2-3% wiring, 5% soiling/shading, plus temperature derating). PVGIS uses 0.75 to 0.80 depending on inverter class.

Worked example for a Birmingham home using 270 kWh/month:

  • Annual target: 270 × 12 × 1.0 = 3,240 kWh
  • System size: 3,240 / (2.6 × 365 × 0.78) = 4.37 kWp
  • Gross cost at £1.55/W: 4,370 × £1.55 = £6,774
  • Typical range: £5,758 to £7,790

UK cost-per-watt by region (2026)

Solar Energy UK and MCS-aggregated quote data, median MCS-installed price, 0% VAT included:

Region£/W median4 kWp typical6 kWp typical
London£1.70£6,800£10,200
South East£1.60£6,400£9,600
South West£1.55£6,200£9,300
East of England£1.55£6,200£9,300
West Midlands£1.50£6,000£9,000
East Midlands£1.50£6,000£9,000
Yorkshire & Humber£1.50£6,000£9,000
North West£1.50£6,000£9,000
North East£1.55£6,200£9,300
Wales£1.55£6,200£9,300
Scotland£1.65£6,600£9,900
Northern Ireland£1.65£6,600£9,900

Sources: Solar Energy UK Cost of Living Crisis Report 2025, MCS quote aggregator, Energy Saving Trust quotes panel.

What is and is not included in £/W

A typical £1.55/W MCS turnkey quote includes:

  • Tier-1 panels MCS-listed (Q CELLS, REC, JA Solar, Trina, Longi, Sharp)
  • Inverter MCS-listed (SolarEdge, GivEnergy, Solis, Fox, Growatt)
  • Roof anchors and rails to BS 7671 + RS-EN 1991-1-4 wind loading
  • DC isolators, AC isolator, Type II surge protection
  • DNO G98 (under 16A) or G99 (over 16A) connection application
  • Scaffolding for two storeys (single storey may save £200 to £400)
  • MCS certification and HIES or RECC consumer protection
  • Building Control notification under Part P
  • 25-year panel warranty, 10-year inverter warranty, 2-year workmanship under MCS

What it does not include:

  • Consumer unit upgrade — £450 to £1,200 (often required in pre-2015 homes)
  • Earthing upgrade — £200 to £600 (PME or TT system fault)
  • Roof repair if tiles or felt are degraded — £500 to £3,000
  • Battery storage — £4,500 to £7,500 for 5 to 10 kWh GivEnergy or Tesla
  • EV charger if added concurrently — £800 to £1,500
  • Bird mesh for pigeon proofing — £300 to £600

Smart Export Guarantee (SEG) and how it affects payback

The SEG (Ofgem-mandated since Jan 2020) requires licensed suppliers with over 150,000 customers to pay you for excess generation exported to the grid. As of 2026:

  • Octopus Outgoing Fixed — 15p/kWh, 12-month fixed, available to Octopus import customers
  • Octopus Outgoing Lite — 8.5p/kWh, no import contract required
  • EDF Export+ — 7.5p/kWh
  • British Gas Export & Earn Plus — 6.4p/kWh
  • OVO — 4.0p/kWh
  • E.ON Next Export Exclusive — 16.5p/kWh (Next import customers only)

Choosing a high-rate SEG tariff can cut payback by 1 to 2 years on a typical 4 kWp system. Most installers pre-register you with their preferred SEG supplier; you can switch independently after MCS certification.

Pair this with the payback calculator, ROI calculator, and savings calculator

Cost gives you the up-front outlay; payback tells you when you break even (typically 8 to 12 years in the UK); ROI gives you the lifetime return; savings shows you the year-over-year cash flow with SEG export earnings.

Sources

Frequently asked questions

How much do solar panels cost in the UK in 2026?
The 2026 UK median installed cost is £1.55/W or about £6,200 for a typical 4 kWp system, per MCS-certified installer surveys aggregated by Solar Energy UK and the Energy Saving Trust. A 6 kWp system runs £8,500 to £10,500 depending on roof complexity. Prices are quoted with the 0% VAT zero-rate (HMRC Notice 708/6) baked in — there is no separate VAT line. Battery storage adds £4,500 to £7,500 for a 5 to 10 kWh GivEnergy or Tesla Powerwall.
Do I still get 0% VAT on solar panels in 2026?
Yes. HMRC Notice 708/6 zero-rates installation of energy-saving materials including solar PV, solar thermal, batteries (since February 2024), and heat pumps in residential dwellings until 31 March 2027. Your installer must apply the zero rate at point of sale — you do not claim it back. The relief covers panels, inverters, batteries, and labour, but not standalone battery purchases by DIY installers (those revert to 20% VAT).
What is a typical 4 kW solar panel system price in the UK?
A 4 kWp system in 2026 typically costs £6,000 to £7,500 fully installed via an MCS-accredited installer. That covers 10 to 12 panels (370-450 W each), a string inverter or hybrid inverter, MCS scaffolding, DNO G98/G99 application, and Building Regs compliance. Add £1,500 to £2,500 if you need a consumer unit upgrade (common in pre-2008 homes) and £4,500 to £6,000 for a 5 kWh battery.
Why are MCS installer quotes more expensive than non-MCS?
MCS certification adds about 8 to 12% to installer overhead because it requires annual audits, MCS-listed equipment, and a complaints procedure via RECC or HIES. The premium is non-negotiable if you want to claim the Smart Export Guarantee (SEG), receive ECO4 funding, or use most renewable-energy mortgages — all require MCS-certified installation. Going non-MCS forfeits export tariff revenue, which typically costs £200 to £500 per year for the system lifetime, far exceeding the up-front saving.
What is the cheapest way to buy solar panels in the UK?
Three legitimate routes to a cheaper installation: (1) bulk-buy schemes like Solar Together (Local Authority-organised group purchases via iChoosr) average 20 to 30% below market; (2) ECO4 funding for low-income households can cover the full installation if you receive certain benefits and your home is EPC E, F, or G; (3) Quote at least three MCS installers via MyBuilder, Checkatrade, or the Energy Saving Trust register — Energy Saving Trust 2024 data shows a 22% spread between top and bottom quotes for identical jobs.

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