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Solar panel cost in Cornwall (TR18)

See realistic solar installation costs, savings and payback for TR18 (Cornwall) in under a minute using official UK data. Start with the calculator, then get a no-obligation quote from an MCS-certified installer. You can also ask the SolarByPostcode assistant to sanity-check your roof, bills and plans.

Solar Calculator

Change the settings below to see how costs and savings work for your situation.

System Size

Roof Direction

Battery Storage

Export Value

Your Numbers

Break-even
10.4 years
After this, it's pure profit
Upfront Cost
£7,307
What you pay to get started
Annual Benefit
£706
What you save every year
Profit Over 25 Years
£10,340
After paying itself off, you're this much ahead

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How we calculate this

Solar generation: Based on typical south-facing roof at 35° angle. We account for weather, dirt, and system losses (14%).

How much you'll use directly:

  • Without battery: You'll use about 40% of what you generate. The rest gets sold back to the grid.
  • With 5 kWh battery: You'll use about 70% (battery stores extra for evening use).
  • With 10 kWh battery: You'll use about 75% (more storage means less exported).
  • Panel-only payback: The official cost per kW is lower above 4 kW, so a 5–6 kW system can pay back a little faster than a 3–4 kW system on otherwise identical assumptions.
  • Battery & payback: Batteries raise self-use and cut bills, but added hardware cost often lengthens break-even at typical UK rates.
  • When a battery can still make sense:
    • Evening-heavy usage patterns
    • Time-of-use tariffs / cheap night rates
    • Low export rate vs. high unit rate
    • Heat pump or EV charging synergy
    • Optional backup/resilience (system-dependent)
    • Lower evening-hour CO₂ vs. grid

Panel costs: Uses March 2026 TIC mean installation costs: £1,827/kW up to 4 kW and £1,628/kW above 4 kW.

Other costs: Battery prices are modelled at £700 per kWh. Export tariffs vary by supplier (usually 5–15p per kWh).

Grid connection: Systems up to about 3.7 kW typically need just a notification (G98). Larger systems may need permission (G99).

These are typical values based on average usage patterns. Your actual results will vary based on your roof, shading, and how you use electricity.

Your area in context

In Southern Western, the current unit rate is 26.39p/kWh with a 57.89p/day standing charge. Your postcode’s south-facing sunshine yield is 1066 kWh/kW — 53 above the regional median (1013).

Read the full story

A typical roof here lands around 4.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1066 kWh per year on a south-facing roof. We value self-used electricity at 26.4p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
26.4p/kWh
Standing charge
57.9p/day
Sunshine yield (south)
1066 kWh/kW
Export price (baseline)
10p/kWh

Browse the scenarios below. Each battery size has its own expand — open the one that matches your plan (or just explore). For each system size (2–8 kW) we show annual output, how much you use directly, what gets exported, annual benefit, upfront cost, break-even, and a 20-year net. Negative numbers are possible — that’s the honest trade-off when adding more battery than your usage profile justifies.

No battery 5 kW example → Annual benefit: £882, Upfront: £9,134, Break-even: 10.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2132 kWh 853 kWh 1279 kWh £225 £128 £353 £3,654 10.4 yrs £3,405
3 kW 3198 kWh 1279 kWh 1919 kWh £338 £192 £529 £5,481 10.4 yrs £5,108
4 kW 4264 kWh 1705 kWh 2558 kWh £450 £256 £706 £7,307 10.4 yrs £6,811
5 kW 5330 kWh 2132 kWh 3198 kWh £563 £320 £882 £9,134 10.4 yrs £8,513
6 kW 6396 kWh 2558 kWh 3837 kWh £675 £384 £1,059 £10,961 10.4 yrs £10,216
7 kW 7462 kWh 2985 kWh 4477 kWh £788 £448 £1,235 £12,788 10.4 yrs £11,919
8 kW 8527 kWh 3411 kWh 5116 kWh £900 £512 £1,412 £14,615 10.4 yrs £13,621

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

3 kWh battery 5 kW example → Annual benefit: £1,057, Upfront: £11,234, Break-even: 10.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2132 kWh 1279 kWh 853 kWh £338 £85 £423 £5,754 13.6 yrs £2,703
3 kW 3198 kWh 1919 kWh 1279 kWh £506 £128 £634 £7,581 12.0 yrs £5,104
4 kW 4264 kWh 2558 kWh 1705 kWh £675 £171 £846 £9,407 11.1 yrs £7,506
5 kW 5330 kWh 3198 kWh 2132 kWh £844 £213 £1,057 £11,234 10.6 yrs £9,907
6 kW 6396 kWh 3837 kWh 2558 kWh £1,013 £256 £1,268 £13,061 10.3 yrs £12,309
7 kW 7462 kWh 4477 kWh 2985 kWh £1,181 £298 £1,480 £14,888 10.1 yrs £14,710
8 kW 8527 kWh 5116 kWh 3411 kWh £1,350 £341 £1,691 £16,715 9.9 yrs £17,112

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

5 kWh battery 5 kW example → Annual benefit: £1,144, Upfront: £12,634, Break-even: 11.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2132 kWh 1492 kWh 640 kWh £394 £64 £458 £7,154 15.6 yrs £2,002
3 kW 3198 kWh 2238 kWh 959 kWh £591 £96 £687 £8,981 13.1 yrs £4,753
4 kW 4264 kWh 2985 kWh 1279 kWh £788 £128 £916 £10,807 11.8 yrs £7,504
5 kW 5330 kWh 3731 kWh 1599 kWh £985 £160 £1,144 £12,634 11.0 yrs £10,255
6 kW 6396 kWh 4477 kWh 1919 kWh £1,181 £192 £1,373 £14,461 10.5 yrs £13,005
7 kW 7462 kWh 5223 kWh 2238 kWh £1,378 £224 £1,602 £16,288 10.2 yrs £15,756
8 kW 8527 kWh 5969 kWh 2558 kWh £1,575 £256 £1,831 £18,115 9.9 yrs £18,507

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

7.5 kWh battery 5 kW example → Annual benefit: £1,171, Upfront: £14,384, Break-even: 12.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2132 kWh 1556 kWh 576 kWh £411 £58 £468 £8,904 19.0 yrs £461
3 kW 3198 kWh 2334 kWh 863 kWh £616 £86 £702 £10,731 15.3 yrs £3,317
4 kW 4264 kWh 3113 kWh 1151 kWh £821 £115 £937 £12,557 13.4 yrs £6,173
5 kW 5330 kWh 3891 kWh 1439 kWh £1,027 £144 £1,171 £14,384 12.3 yrs £9,029
6 kW 6396 kWh 4669 kWh 1727 kWh £1,232 £173 £1,405 £16,211 11.5 yrs £11,884
7 kW 7462 kWh 5447 kWh 2015 kWh £1,437 £201 £1,639 £18,038 11.0 yrs £14,740
8 kW 8527 kWh 6225 kWh 2302 kWh £1,643 £230 £1,873 £19,865 10.6 yrs £17,596

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

10 kWh battery 5 kW example → Annual benefit: £1,188, Upfront: £16,134, Break-even: 13.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2132 kWh 1599 kWh 533 kWh £422 £53 £475 £10,654 22.4 yrs £-1,149
3 kW 3198 kWh 2398 kWh 799 kWh £633 £80 £713 £12,481 17.5 yrs £1,777
4 kW 4264 kWh 3198 kWh 1066 kWh £844 £107 £950 £14,307 15.1 yrs £4,702
5 kW 5330 kWh 3997 kWh 1332 kWh £1,055 £133 £1,188 £16,134 13.6 yrs £7,628
6 kW 6396 kWh 4797 kWh 1599 kWh £1,266 £160 £1,426 £17,961 12.6 yrs £10,554
7 kW 7462 kWh 5596 kWh 1865 kWh £1,477 £187 £1,663 £19,788 11.9 yrs £13,479
8 kW 8527 kWh 6396 kWh 2132 kWh £1,688 £213 £1,901 £21,615 11.4 yrs £16,405

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

13.5 kWh battery 5 kW example → Annual benefit: £1,206, Upfront: £18,584, Break-even: 15.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2132 kWh 1642 kWh 490 kWh £433 £49 £482 £13,104 27.2 yrs £-3,459
3 kW 3198 kWh 2462 kWh 735 kWh £650 £74 £723 £14,931 20.6 yrs £-464
4 kW 4264 kWh 3283 kWh 981 kWh £866 £98 £964 £16,757 17.4 yrs £2,532
5 kW 5330 kWh 4104 kWh 1226 kWh £1,083 £123 £1,206 £18,584 15.4 yrs £5,527
6 kW 6396 kWh 4925 kWh 1471 kWh £1,300 £147 £1,447 £20,411 14.1 yrs £8,523
7 kW 7462 kWh 5745 kWh 1716 kWh £1,516 £172 £1,688 £22,238 13.2 yrs £11,518
8 kW 8527 kWh 6566 kWh 1961 kWh £1,733 £196 £1,929 £24,065 12.5 yrs £14,514

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

Figures are illustrative and use the same method as the calculator above. For exact results, adjust your roof direction, tariff, and usage in the calculator.

Before you request quotes in Cornwall

Use the numbers above to sanity-check installer quotes. The main things to compare are system size, battery assumptions, payback claims, MCS certification, DNO paperwork and export assumptions.

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Check what MCS certification means

Understand DNO, G98 and G99 export limits

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This is a practical sanity-check request, not an instant quote promise. The Blue Ape quote route above remains available if you already want installer introductions.

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Insights for TR18

Figures below are tailored to TR18 — click through for full league tables.

Big-Roof Britain Rank #1870 of 2182
4.3 kWp (UK avg 5.1 kWp)
~9 panels (≈430 W)
Solar Payback Index Rank #1430 of 2996
10.3 years (UK avg 10.8 years)
~£706 /yr • £7,307 upfront
Standing-Charge Drag Rank #2139 of 2996
29.9% (UK avg 26.6%) drag on savings
£211 fixed • ~£706 /yr value
Aspect Penalty View ranking →
East −18.9% West −21.3%
Typical output loss versus a south-facing roof (lower is better)

Seasonal solar output in TR18

Monthly generation per kilowatt of solar panels

kWh 39 Jan 56 Feb 89 Mar 123 Apr 132 May 131 Jun 129 Jul 121 Aug 99 Sep 69 Oct 44 Nov 33 Dec
Best month Worst month Winter (Dec–Feb) Other months

Winter output: 48.2% of an average month (Dec–Feb)

Best / worst month: May / Dec

These figures show output per kilowatt (kW) of panels installed. In winter, a 1 kW system here produces about 43 kWh per month; the average month produces around 89 kWh. So a typical 4 kW home system would generate roughly 171 kWh in winter, or 355 kWh in an average month.

Your Area at a Glance

Your Electricity Rate
26.39p/kWh
Daily Fixed Charge
57.89p/day
Local Sunshine
1066kWh/kW
A 1 kW system generates ~1066 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
4.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 55% • Flats: 34% • Bungalows: 8% Based on 7,006 properties

Coverage

Cornwall (100%)

Areas Covered

Penzance East, Penzance Promenade, Mousehole, Newlyn & St Buryan, Ludgvan, Madron, Gulval & Heamoor, Long Rock + 3 more

Data Sources & Assumptions

Solar yield: PVGIS (EU Joint Research Centre), January 2025 data

Electricity rates: Ofgem price cap, Q3 2026

Installation costs: DESNZ/MCS data, March 2026 (TIC)

Property data: EPC open data (Open Government Licence), aggregated

All estimates are typical values. Actual results vary based on your specific situation, roof characteristics, and usage patterns.

Compare nearby areas

Nearby in Southern Western

TR93 (Cornwall)
≈2.9 km away
Local sunshine: ~1,066 kWh/kWp · +0% vs TR18
TR20 (Cornwall)
≈3.4 km away
Local sunshine: ~1,067 kWh/kWp · +0% vs TR18
TR17 (Cornwall)
≈5.1 km away
Local sunshine: ~1,067 kWh/kWp · +0% vs TR18
TR19 (Cornwall)
≈8.8 km away
Local sunshine: ~1,083 kWh/kWp · +2% vs TR18
TR26 (Cornwall)
≈10.4 km away
Local sunshine: ~1,009 kWh/kWp · -5% vs TR18
TR27 (Cornwall)
≈11.6 km away
Local sunshine: ~1,067 kWh/kWp · +0% vs TR18

Similar sunshine across the UK

DT2 (Dorset)
~1,066 kWh/kWp · +0% vs TR18
SS3 (Southend-on-Sea)
~1,066 kWh/kWp · +0% vs TR18
BN8 (Lewes)
~1,067 kWh/kWp · +0% vs TR18