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

Solar Panels in SA5 (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
12.3 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£827
What you save every year
Profit Over 25 Years
£10,504
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

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 989 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)
989 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: £827, Upfront: £10,173, 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 1977 kWh 791 kWh 1186 kWh £212 £119 £331 £4,069 12.3 yrs £2,548
3 kW 2966 kWh 1186 kWh 1780 kWh £318 £178 £496 £6,104 12.3 yrs £3,821
4 kW 3954 kWh 1582 kWh 2373 kWh £424 £237 £662 £8,138 12.3 yrs £5,095
5 kW 4943 kWh 1977 kWh 2966 kWh £530 £297 £827 £10,173 12.3 yrs £6,369
6 kW 5932 kWh 2373 kWh 3559 kWh £637 £356 £992 £12,207 12.3 yrs £7,643
7 kW 6920 kWh 2768 kWh 4152 kWh £743 £415 £1,158 £14,242 12.3 yrs £8,917
8 kW 7909 kWh 3164 kWh 4745 kWh £849 £475 £1,323 £16,276 12.3 yrs £10,190

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: £993, Upfront: £12,273, Break-even: 12.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1977 kWh 1186 kWh 791 kWh £318 £79 £397 £6,169 15.5 yrs £1,779
3 kW 2966 kWh 1780 kWh 1186 kWh £477 £119 £596 £8,204 13.8 yrs £3,718
4 kW 3954 kWh 2373 kWh 1582 kWh £637 £158 £795 £10,238 12.9 yrs £5,657
5 kW 4943 kWh 2966 kWh 1977 kWh £796 £198 £993 £12,273 12.4 yrs £7,597
6 kW 5932 kWh 3559 kWh 2373 kWh £955 £237 £1,192 £14,307 12.0 yrs £9,536
7 kW 6920 kWh 4152 kWh 2768 kWh £1,114 £277 £1,391 £16,342 11.7 yrs £11,475
8 kW 7909 kWh 4745 kWh 3164 kWh £1,273 £316 £1,590 £18,376 11.6 yrs £13,415

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: £1,077, Upfront: £13,673, Break-even: 12.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1977 kWh 1384 kWh 593 kWh £371 £59 £431 £7,569 17.6 yrs £1,044
3 kW 2966 kWh 2076 kWh 890 kWh £557 £89 £646 £9,604 14.9 yrs £3,316
4 kW 3954 kWh 2768 kWh 1186 kWh £743 £119 £861 £11,638 13.5 yrs £5,588
5 kW 4943 kWh 3460 kWh 1483 kWh £928 £148 £1,077 £13,673 12.7 yrs £7,861
6 kW 5932 kWh 4152 kWh 1780 kWh £1,114 £178 £1,292 £15,707 12.2 yrs £10,133
7 kW 6920 kWh 4844 kWh 2076 kWh £1,300 £208 £1,507 £17,742 11.8 yrs £12,405
8 kW 7909 kWh 5536 kWh 2373 kWh £1,485 £237 £1,723 £19,776 11.5 yrs £14,677

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: £1,102, Upfront: £15,423, 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 1977 kWh 1443 kWh 534 kWh £387 £53 £441 £9,319 21.1 yrs £-506
3 kW 2966 kWh 2165 kWh 801 kWh £581 £80 £661 £11,354 17.2 yrs £1,866
4 kW 3954 kWh 2887 kWh 1068 kWh £775 £107 £881 £13,388 15.2 yrs £4,238
5 kW 4943 kWh 3608 kWh 1335 kWh £968 £133 £1,102 £15,423 14.0 yrs £6,610
6 kW 5932 kWh 4330 kWh 1602 kWh £1,162 £160 £1,322 £17,457 13.2 yrs £8,982
7 kW 6920 kWh 5052 kWh 1868 kWh £1,355 £187 £1,542 £19,492 12.6 yrs £11,354
8 kW 7909 kWh 5774 kWh 2135 kWh £1,549 £214 £1,763 £21,526 12.2 yrs £13,726

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: £1,118, Upfront: £17,173, 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 1977 kWh 1483 kWh 494 kWh £398 £49 £447 £11,069 24.7 yrs £-2,123
3 kW 2966 kWh 2224 kWh 741 kWh £597 £74 £671 £13,104 19.5 yrs £316
4 kW 3954 kWh 2966 kWh 989 kWh £796 £99 £895 £15,138 16.9 yrs £2,754
5 kW 4943 kWh 3707 kWh 1236 kWh £995 £124 £1,118 £17,173 15.4 yrs £5,193
6 kW 5932 kWh 4449 kWh 1483 kWh £1,194 £148 £1,342 £19,207 14.3 yrs £7,631
7 kW 6920 kWh 5190 kWh 1730 kWh £1,393 £173 £1,566 £21,242 13.6 yrs £10,070
8 kW 7909 kWh 5932 kWh 1977 kWh £1,591 £198 £1,789 £23,276 13.0 yrs £12,508

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: £1,135, Upfront: £19,623, Break-even: 17.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1977 kWh 1522 kWh 455 kWh £408 £45 £454 £13,519 29.8 yrs £-4,440
3 kW 2966 kWh 2284 kWh 682 kWh £613 £68 £681 £15,554 22.8 yrs £-1,935
4 kW 3954 kWh 3045 kWh 910 kWh £817 £91 £908 £17,588 19.4 yrs £570
5 kW 4943 kWh 3806 kWh 1137 kWh £1,021 £114 £1,135 £19,623 17.3 yrs £3,075
6 kW 5932 kWh 4567 kWh 1364 kWh £1,225 £136 £1,362 £21,657 15.9 yrs £5,580
7 kW 6920 kWh 5329 kWh 1592 kWh £1,430 £159 £1,589 £23,692 14.9 yrs £8,085
8 kW 7909 kWh 6090 kWh 1819 kWh £1,634 £182 £1,816 £25,726 14.2 yrs £10,590

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
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
989kWh/kW
A 1 kW system generates ~989 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: 77% • Flats: 15% • Bungalows: 5% Based on 7,348 properties

Coverage

Swansea (100%)

Areas Covered

Cockett, Penderry, Cwmbwrla, Mynydd-bach, Waunarlwydd, Llangyfelach, Llansamlet, Landore + 4 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.