Solar explained to clever people by people who are not trying to be clever

Solar Panels in TR2 (Cornwall)

See if solar pays off for you in Cornwall — price, savings and payback in under a minute (official UK data).

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
11.7 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£1,044
What you save every year
Profit Over 25 Years
£13,902
After paying itself off, you're this much ahead

Ready to Get Started?

Get your free quote from Blue Ape Renewables. They'll connect you with MCS-certified installers in your area and handle all the paperwork.

Get Solar Quote →
4.8★ Trustpilot • Octopus Energy trusted partner • MCS certified • No obligation
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: Bigger systems don’t shorten payback—cost and savings rise together per kW.
  • 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

Costs: Battery prices are typically £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

Read the full story

A typical roof here lands around 6.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1041 kWh per year on a south-facing roof. We value self-used electricity at 26.8p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
26.8p/kWh
Standing charge
54.0p/day
Sunshine yield (south)
1041 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: £870, Upfront: £10,173, Break-even: 11.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2081 kWh 832 kWh 1249 kWh £223 £125 £348 £4,069 11.7 yrs £2,893
3 kW 3122 kWh 1249 kWh 1873 kWh £335 £187 £522 £6,104 11.7 yrs £4,340
4 kW 4162 kWh 1665 kWh 2497 kWh £447 £250 £696 £8,138 11.7 yrs £5,787
5 kW 5203 kWh 2081 kWh 3122 kWh £558 £312 £870 £10,173 11.7 yrs £7,233
6 kW 6243 kWh 2497 kWh 3746 kWh £670 £375 £1,044 £12,207 11.7 yrs £8,680
7 kW 7284 kWh 2913 kWh 4370 kWh £781 £437 £1,218 £14,242 11.7 yrs £10,127
8 kW 8324 kWh 3330 kWh 4994 kWh £893 £499 £1,392 £16,276 11.7 yrs £11,573

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

3 kWh battery 5 kW example → Annual benefit: £1,045, Upfront: £12,273, Break-even: 11.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2081 kWh 1249 kWh 832 kWh £335 £83 £418 £6,169 14.8 yrs £2,193
3 kW 3122 kWh 1873 kWh 1249 kWh £502 £125 £627 £8,204 13.1 yrs £4,340
4 kW 4162 kWh 2497 kWh 1665 kWh £670 £166 £836 £10,238 12.2 yrs £6,487
5 kW 5203 kWh 3122 kWh 2081 kWh £837 £208 £1,045 £12,273 11.7 yrs £8,634
6 kW 6243 kWh 3746 kWh 2497 kWh £1,005 £250 £1,254 £14,307 11.4 yrs £10,780
7 kW 7284 kWh 4370 kWh 2913 kWh £1,172 £291 £1,463 £16,342 11.2 yrs £12,927
8 kW 8324 kWh 4994 kWh 3330 kWh £1,340 £333 £1,672 £18,376 11.0 yrs £15,074

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

5 kWh battery 5 kW example → Annual benefit: £1,133, Upfront: £13,673, Break-even: 12.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2081 kWh 1457 kWh 624 kWh £391 £62 £453 £7,569 16.7 yrs £1,493
3 kW 3122 kWh 2185 kWh 936 kWh £586 £94 £680 £9,604 14.1 yrs £3,990
4 kW 4162 kWh 2913 kWh 1249 kWh £781 £125 £906 £11,638 12.8 yrs £6,487
5 kW 5203 kWh 3642 kWh 1561 kWh £977 £156 £1,133 £13,673 12.1 yrs £8,984
6 kW 6243 kWh 4370 kWh 1873 kWh £1,172 £187 £1,359 £15,707 11.6 yrs £11,480
7 kW 7284 kWh 5099 kWh 2185 kWh £1,367 £219 £1,586 £17,742 11.2 yrs £13,977
8 kW 8324 kWh 5827 kWh 2497 kWh £1,563 £250 £1,813 £19,776 10.9 yrs £16,474

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

7.5 kWh battery 5 kW example → Annual benefit: £1,159, Upfront: £15,423, Break-even: 13.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2081 kWh 1519 kWh 562 kWh £407 £56 £464 £9,319 20.1 yrs £-46
3 kW 3122 kWh 2279 kWh 843 kWh £611 £84 £695 £11,354 16.3 yrs £2,555
4 kW 4162 kWh 3038 kWh 1124 kWh £815 £112 £927 £13,388 14.4 yrs £5,157
5 kW 5203 kWh 3798 kWh 1405 kWh £1,019 £140 £1,159 £15,423 13.3 yrs £7,759
6 kW 6243 kWh 4557 kWh 1686 kWh £1,222 £169 £1,391 £17,457 12.6 yrs £10,361
7 kW 7284 kWh 5317 kWh 1967 kWh £1,426 £197 £1,623 £19,492 12.0 yrs £12,962
8 kW 8324 kWh 6077 kWh 2248 kWh £1,630 £225 £1,855 £21,526 11.6 yrs £15,564

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

10 kWh battery 5 kW example → Annual benefit: £1,177, Upfront: £17,173, Break-even: 14.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2081 kWh 1561 kWh 520 kWh £419 £52 £471 £11,069 23.5 yrs £-1,656
3 kW 3122 kWh 2341 kWh 780 kWh £628 £78 £706 £13,104 18.6 yrs £1,015
4 kW 4162 kWh 3122 kWh 1041 kWh £837 £104 £941 £15,138 16.1 yrs £3,687
5 kW 5203 kWh 3902 kWh 1301 kWh £1,047 £130 £1,177 £17,173 14.6 yrs £6,359
6 kW 6243 kWh 4682 kWh 1561 kWh £1,256 £156 £1,412 £19,207 13.6 yrs £9,031
7 kW 7284 kWh 5463 kWh 1821 kWh £1,465 £182 £1,647 £21,242 12.9 yrs £11,702
8 kW 8324 kWh 6243 kWh 2081 kWh £1,674 £208 £1,883 £23,276 12.4 yrs £14,374

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

13.5 kWh battery 5 kW example → Annual benefit: £1,194, Upfront: £19,623, Break-even: 16.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2081 kWh 1602 kWh 479 kWh £430 £48 £478 £13,519 28.3 yrs £-3,966
3 kW 3122 kWh 2404 kWh 718 kWh £645 £72 £716 £15,554 21.7 yrs £-1,225
4 kW 4162 kWh 3205 kWh 957 kWh £860 £96 £955 £17,588 18.4 yrs £1,517
5 kW 5203 kWh 4006 kWh 1197 kWh £1,074 £120 £1,194 £19,623 16.4 yrs £4,259
6 kW 6243 kWh 4807 kWh 1436 kWh £1,289 £144 £1,433 £21,657 15.1 yrs £7,001
7 kW 7284 kWh 5608 kWh 1675 kWh £1,504 £168 £1,672 £23,692 14.2 yrs £9,742
8 kW 8324 kWh 6410 kWh 1915 kWh £1,719 £191 £1,911 £25,726 13.5 yrs £12,484

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, 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.

Your Area at a Glance

Your Electricity Rate
26.82p/kWh
Daily Fixed Charge
54.03p/day
Local Sunshine
1041kWh/kW
A 1 kW system generates ~1041 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
6.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 75% • Flats: 7% • Bungalows: 17% Based on 3,473 properties

Coverage

Cornwall (100%)

Areas Covered

St Goran, Tregony & the Roseland, Probus & St Erme, St Mewan & Grampound, Truro Boscawen & Redannick, St Stephen-in-Brannel, St Dennis & St Enoder

Data Sources & Assumptions

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

Electricity rates: Ofgem price cap, Q4 2025

Installation costs: MCS certified installer data, March 2025

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.