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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in TR13 (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
11.2 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£905
What you save every year
Profit Over 25 Years
£12,455
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: 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

In Southern Western, the current unit rate is 26.82p/kWh with a 54.03p/day standing charge. Your postcode’s south-facing sunshine yield is 1082 kWh/kW — 69 above the regional median (1013).

Read the full story

A typical roof here lands around 5.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1082 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)
1082 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: £905, Upfront: £10,173, Break-even: 11.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2164 kWh 866 kWh 1299 kWh £232 £130 £362 £4,069 11.2 yrs £3,172
3 kW 3246 kWh 1299 kWh 1948 kWh £348 £195 £543 £6,104 11.2 yrs £4,758
4 kW 4329 kWh 1731 kWh 2597 kWh £464 £260 £724 £8,138 11.2 yrs £6,343
5 kW 5411 kWh 2164 kWh 3246 kWh £580 £325 £905 £10,173 11.2 yrs £7,929
6 kW 6493 kWh 2597 kWh 3896 kWh £697 £390 £1,086 £12,207 11.2 yrs £9,515
7 kW 7575 kWh 3030 kWh 4545 kWh £813 £454 £1,267 £14,242 11.2 yrs £11,101
8 kW 8657 kWh 3463 kWh 5194 kWh £929 £519 £1,448 £16,276 11.2 yrs £12,687

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: £1,087, Upfront: £12,273, Break-even: 11.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2164 kWh 1299 kWh 866 kWh £348 £87 £435 £6,169 14.2 yrs £2,528
3 kW 3246 kWh 1948 kWh 1299 kWh £522 £130 £652 £8,204 12.6 yrs £4,842
4 kW 4329 kWh 2597 kWh 1731 kWh £697 £173 £870 £10,238 11.8 yrs £7,156
5 kW 5411 kWh 3246 kWh 2164 kWh £871 £216 £1,087 £12,273 11.3 yrs £9,470
6 kW 6493 kWh 3896 kWh 2597 kWh £1,045 £260 £1,305 £14,307 11.0 yrs £11,784
7 kW 7575 kWh 4545 kWh 3030 kWh £1,219 £303 £1,522 £16,342 10.7 yrs £14,097
8 kW 8657 kWh 5194 kWh 3463 kWh £1,393 £346 £1,739 £18,376 10.6 yrs £16,411

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: £1,178, Upfront: £13,673, Break-even: 11.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2164 kWh 1515 kWh 649 kWh £406 £65 £471 £7,569 16.1 yrs £1,856
3 kW 3246 kWh 2272 kWh 974 kWh £609 £97 £707 £9,604 13.6 yrs £4,534
4 kW 4329 kWh 3030 kWh 1299 kWh £813 £130 £942 £11,638 12.3 yrs £7,212
5 kW 5411 kWh 3787 kWh 1623 kWh £1,016 £162 £1,178 £13,673 11.6 yrs £9,890
6 kW 6493 kWh 4545 kWh 1948 kWh £1,219 £195 £1,414 £15,707 11.1 yrs £12,568
7 kW 7575 kWh 5302 kWh 2272 kWh £1,422 £227 £1,649 £17,742 10.8 yrs £15,246
8 kW 8657 kWh 6060 kWh 2597 kWh £1,625 £260 £1,885 £19,776 10.5 yrs £17,924

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: £1,205, Upfront: £15,423, Break-even: 12.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2164 kWh 1580 kWh 584 kWh £424 £58 £482 £9,319 19.3 yrs £324
3 kW 3246 kWh 2370 kWh 877 kWh £636 £88 £723 £11,354 15.7 yrs £3,111
4 kW 4329 kWh 3160 kWh 1169 kWh £847 £117 £964 £13,388 13.9 yrs £5,899
5 kW 5411 kWh 3950 kWh 1461 kWh £1,059 £146 £1,205 £15,423 12.8 yrs £8,686
6 kW 6493 kWh 4740 kWh 1753 kWh £1,271 £175 £1,447 £17,457 12.1 yrs £11,473
7 kW 7575 kWh 5530 kWh 2045 kWh £1,483 £205 £1,688 £19,492 11.5 yrs £14,260
8 kW 8657 kWh 6320 kWh 2337 kWh £1,695 £234 £1,929 £21,526 11.2 yrs £17,047

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: £1,224, Upfront: £17,173, Break-even: 14.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2164 kWh 1623 kWh 541 kWh £435 £54 £489 £11,069 22.6 yrs £-1,280
3 kW 3246 kWh 2435 kWh 812 kWh £653 £81 £734 £13,104 17.8 yrs £1,580
4 kW 4329 kWh 3246 kWh 1082 kWh £871 £108 £979 £15,138 15.5 yrs £4,440
5 kW 5411 kWh 4058 kWh 1353 kWh £1,088 £135 £1,224 £17,173 14.0 yrs £7,300
6 kW 6493 kWh 4870 kWh 1623 kWh £1,306 £162 £1,468 £19,207 13.1 yrs £10,160
7 kW 7575 kWh 5681 kWh 1894 kWh £1,524 £189 £1,713 £21,242 12.4 yrs £13,020
8 kW 8657 kWh 6493 kWh 2164 kWh £1,741 £216 £1,958 £23,276 11.9 yrs £15,880

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: £1,242, Upfront: £19,623, Break-even: 15.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2164 kWh 1666 kWh 498 kWh £447 £50 £497 £13,519 27.2 yrs £-3,584
3 kW 3246 kWh 2500 kWh 747 kWh £670 £75 £745 £15,554 20.9 yrs £-652
4 kW 4329 kWh 3333 kWh 996 kWh £894 £100 £993 £17,588 17.7 yrs £2,281
5 kW 5411 kWh 4166 kWh 1244 kWh £1,117 £124 £1,242 £19,623 15.8 yrs £5,214
6 kW 6493 kWh 4999 kWh 1493 kWh £1,341 £149 £1,490 £21,657 14.5 yrs £8,147
7 kW 7575 kWh 5833 kWh 1742 kWh £1,564 £174 £1,739 £23,692 13.6 yrs £11,079
8 kW 8657 kWh 6666 kWh 1991 kWh £1,788 £199 £1,987 £25,726 12.9 yrs £14,012

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.

Insights for TR13

Figures below are tailored to TR13 — click through for full league tables.

Big-Roof Britain Rank #833 of 2182
5.2 kWp (UK avg 5.1 kWp)
~11 panels (≈430 W)
Solar Payback Index Rank #142 of 2997
9.8 years (UK avg 11.3 years)
~£1,042 /yr • £10,173 upfront
Standing-Charge Drag Rank #1222 of 2997
18.9% (UK avg 21.7%) drag on savings
£197 fixed • ~£1,042 /yr value

Your Area at a Glance

Your Electricity Rate
26.82p/kWh
Daily Fixed Charge
54.03p/day
Local Sunshine
1082kWh/kW
A 1 kW system generates ~1082 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
5.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 66% • Flats: 14% • Bungalows: 19% Based on 6,407 properties

Coverage

Cornwall (100%)

Areas Covered

Porthleven, Breage & Germoe, Helston South & Meneage, Helston North, Crowan, Sithney & Wendron, Mullion & St Keverne

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.

Compare nearby areas

Nearby in Southern Western

TR12 (Cornwall)
≈8.0 km away
Local sunshine: ~1,097 kWh/kWp · +1% vs TR13
TR14 (Cornwall)
≈12.4 km away
Local sunshine: ~1,008 kWh/kWp · -7% vs TR13
TR27 (Cornwall)
≈13.3 km away
Local sunshine: ~1,067 kWh/kWp · -1% vs TR13
TR10 (Cornwall)
≈13.8 km away
Local sunshine: ~1,027 kWh/kWp · -5% vs TR13
TR17 (Cornwall)
≈14.0 km away
Local sunshine: ~1,067 kWh/kWp · -1% vs TR13
TR11 (Cornwall)
≈14.8 km away
Local sunshine: ~1,021 kWh/kWp · -6% vs TR13

Similar sunshine across the UK

BN5 (Horsham)
~1,083 kWh/kWp · +0% vs TR13
SS5 (Rochford)
~1,083 kWh/kWp · +0% vs TR13
BH11 (Bournemouth, Christchurch and Poole)
~1,081 kWh/kWp · -0% vs TR13