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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in SA3 (Swansea)

See if solar pays off for you in Swansea — 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
11.6 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£1,048
What you save every year
Profit Over 25 Years
£13,996
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 South Wales, the current unit rate is 26.83p/kWh with a 51.69p/day standing charge. Your postcode’s south-facing sunshine yield is 1044 kWh/kW — 76 above the regional median (968).

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 1044 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
51.7p/day
Sunshine yield (south)
1044 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: £873, Upfront: £10,173, 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 2088 kWh 835 kWh 1253 kWh £224 £125 £349 £4,069 11.6 yrs £2,918
3 kW 3132 kWh 1253 kWh 1879 kWh £336 £188 £524 £6,104 11.6 yrs £4,378
4 kW 4176 kWh 1670 kWh 2506 kWh £448 £251 £699 £8,138 11.6 yrs £5,837
5 kW 5220 kWh 2088 kWh 3132 kWh £560 £313 £873 £10,173 11.6 yrs £7,296
6 kW 6264 kWh 2506 kWh 3758 kWh £672 £376 £1,048 £12,207 11.6 yrs £8,755
7 kW 7308 kWh 2923 kWh 4385 kWh £784 £438 £1,223 £14,242 11.6 yrs £10,214
8 kW 8352 kWh 3341 kWh 5011 kWh £896 £501 £1,397 £16,276 11.6 yrs £11,674

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: £1,049, 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 2088 kWh 1253 kWh 835 kWh £336 £84 £420 £6,169 14.7 yrs £2,224
3 kW 3132 kWh 1879 kWh 1253 kWh £504 £125 £629 £8,204 13.0 yrs £4,386
4 kW 4176 kWh 2506 kWh 1670 kWh £672 £167 £839 £10,238 12.2 yrs £6,548
5 kW 5220 kWh 3132 kWh 2088 kWh £840 £209 £1,049 £12,273 11.7 yrs £8,710
6 kW 6264 kWh 3758 kWh 2506 kWh £1,008 £251 £1,259 £14,307 11.4 yrs £10,872
7 kW 7308 kWh 4385 kWh 2923 kWh £1,176 £292 £1,469 £16,342 11.1 yrs £13,034
8 kW 8352 kWh 5011 kWh 3341 kWh £1,345 £334 £1,679 £18,376 10.9 yrs £15,196

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: £1,137, Upfront: £13,673, Break-even: 12.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2088 kWh 1462 kWh 626 kWh £392 £63 £455 £7,569 16.6 yrs £1,527
3 kW 3132 kWh 2192 kWh 940 kWh £588 £94 £682 £9,604 14.1 yrs £4,040
4 kW 4176 kWh 2923 kWh 1253 kWh £784 £125 £910 £11,638 12.8 yrs £6,554
5 kW 5220 kWh 3654 kWh 1566 kWh £980 £157 £1,137 £13,673 12.0 yrs £9,067
6 kW 6264 kWh 4385 kWh 1879 kWh £1,176 £188 £1,364 £15,707 11.5 yrs £11,581
7 kW 7308 kWh 5116 kWh 2192 kWh £1,373 £219 £1,592 £17,742 11.1 yrs £14,094
8 kW 8352 kWh 5847 kWh 2506 kWh £1,569 £251 £1,819 £19,776 10.9 yrs £16,608

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: £1,163, 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 2088 kWh 1524 kWh 564 kWh £409 £56 £465 £9,319 20.0 yrs £-12
3 kW 3132 kWh 2286 kWh 846 kWh £613 £85 £698 £11,354 16.3 yrs £2,607
4 kW 4176 kWh 3049 kWh 1128 kWh £818 £113 £931 £13,388 14.4 yrs £5,226
5 kW 5220 kWh 3811 kWh 1409 kWh £1,022 £141 £1,163 £15,423 13.3 yrs £7,844
6 kW 6264 kWh 4573 kWh 1691 kWh £1,227 £169 £1,396 £17,457 12.5 yrs £10,463
7 kW 7308 kWh 5335 kWh 1973 kWh £1,431 £197 £1,629 £19,492 12.0 yrs £13,082
8 kW 8352 kWh 6097 kWh 2255 kWh £1,636 £226 £1,861 £21,526 11.6 yrs £15,701

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: £1,181, Upfront: £17,173, Break-even: 14.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2088 kWh 1566 kWh 522 kWh £420 £52 £472 £11,069 23.4 yrs £-1,622
3 kW 3132 kWh 2349 kWh 783 kWh £630 £78 £709 £13,104 18.5 yrs £1,067
4 kW 4176 kWh 3132 kWh 1044 kWh £840 £104 £945 £15,138 16.0 yrs £3,757
5 kW 5220 kWh 3915 kWh 1305 kWh £1,050 £131 £1,181 £17,173 14.5 yrs £6,446
6 kW 6264 kWh 4698 kWh 1566 kWh £1,260 £157 £1,417 £19,207 13.6 yrs £9,135
7 kW 7308 kWh 5481 kWh 1827 kWh £1,471 £183 £1,653 £21,242 12.8 yrs £11,824
8 kW 8352 kWh 6264 kWh 2088 kWh £1,681 £209 £1,889 £23,276 12.3 yrs £14,513

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: £1,198, 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 2088 kWh 1608 kWh 480 kWh £431 £48 £479 £13,519 28.2 yrs £-3,931
3 kW 3132 kWh 2412 kWh 720 kWh £647 £72 £719 £15,554 21.6 yrs £-1,172
4 kW 4176 kWh 3216 kWh 960 kWh £863 £96 £959 £17,588 18.3 yrs £1,588
5 kW 5220 kWh 4019 kWh 1201 kWh £1,078 £120 £1,198 £19,623 16.4 yrs £4,347
6 kW 6264 kWh 4823 kWh 1441 kWh £1,294 £144 £1,438 £21,657 15.1 yrs £7,107
7 kW 7308 kWh 5627 kWh 1681 kWh £1,510 £168 £1,678 £23,692 14.1 yrs £9,866
8 kW 8352 kWh 6431 kWh 1921 kWh £1,725 £192 £1,918 £25,726 13.4 yrs £12,626

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 SA3

Figures below are tailored to SA3 — click through for full league tables.

Big-Roof Britain Rank #156 of 2182
6.3 kWp (UK avg 5.1 kWp)
~13 panels (≈430 W)
Solar Payback Index Rank #239 of 2997
10.1 years (UK avg 11.3 years)
~£1,206 /yr • £12,207 upfront
Standing-Charge Drag Rank #501 of 2997
15.6% (UK avg 21.7%) drag on savings
£189 fixed • ~£1,206 /yr value

Your Area at a Glance

Your Electricity Rate
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
1044kWh/kW
A 1 kW system generates ~1044 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: 67% • Flats: 16% • Bungalows: 15% Based on 6,516 properties

Coverage

Swansea (100%)

Areas Covered

Mumbles, West Cross, Gower, Bishopston, Mayals, Pennard, Llansamlet, Uplands + 2 more

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 South Wales

SA2 (Swansea)
≈5.0 km away
Local sunshine: ~988 kWh/kWp · -5% vs SA3
SA1 (Swansea)
≈7.0 km away
Local sunshine: ~982 kWh/kWp · -6% vs SA3
SA5 (Swansea)
≈8.2 km away
Local sunshine: ~989 kWh/kWp · -5% vs SA3
SA80 (Swansea)
≈9.8 km away
Local sunshine: ~982 kWh/kWp · -6% vs SA3
SA4 (Swansea)
≈10.5 km away
Local sunshine: ~961 kWh/kWp · -8% vs SA3
SA99 (Swansea)
≈11.2 km away
Local sunshine: ~968 kWh/kWp · -7% vs SA3

Similar sunshine across the UK

ME13 (Swale)
~1,044 kWh/kWp · -0% vs SA3
ME15 (Maidstone)
~1,044 kWh/kWp · +0% vs SA3
TQ3 (Torbay)
~1,044 kWh/kWp · -0% vs SA3