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Solar panel cost in Carmarthenshire (SA20)

See realistic solar installation costs, savings and payback for SA20 (Carmarthenshire) 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
15.4 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£794
What you save every year
Profit Over 25 Years
£7,639
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 23.31p/kWh with a 56.85p/day standing charge. Your postcode’s south-facing sunshine yield is 863 kWh/kW — 105 below 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 863 kWh per year on a south-facing roof. We value self-used electricity at 23.3p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
23.3p/kWh
Standing charge
56.9p/day
Sunshine yield (south)
863 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: £662, Upfront: £10,173, 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 1727 kWh 691 kWh 1036 kWh £161 £104 £265 £4,069 15.4 yrs £1,223
3 kW 2590 kWh 1036 kWh 1554 kWh £242 £155 £397 £6,104 15.4 yrs £1,835
4 kW 3454 kWh 1381 kWh 2072 kWh £322 £207 £529 £8,138 15.4 yrs £2,446
5 kW 4317 kWh 1727 kWh 2590 kWh £403 £259 £662 £10,173 15.4 yrs £3,058
6 kW 5180 kWh 2072 kWh 3108 kWh £483 £311 £794 £12,207 15.4 yrs £3,669
7 kW 6044 kWh 2417 kWh 3626 kWh £564 £363 £926 £14,242 15.4 yrs £4,281
8 kW 6907 kWh 2763 kWh 4144 kWh £644 £414 £1,058 £16,276 15.4 yrs £4,893

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: £776, Upfront: £12,273, 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 1727 kWh 1036 kWh 691 kWh £242 £69 £311 £6,169 19.9 yrs £42
3 kW 2590 kWh 1554 kWh 1036 kWh £362 £104 £466 £8,204 17.6 yrs £1,114
4 kW 3454 kWh 2072 kWh 1381 kWh £483 £138 £621 £10,238 16.5 yrs £2,185
5 kW 4317 kWh 2590 kWh 1727 kWh £604 £173 £776 £12,273 15.8 yrs £3,256
6 kW 5180 kWh 3108 kWh 2072 kWh £725 £207 £932 £14,307 15.4 yrs £4,327
7 kW 6044 kWh 3626 kWh 2417 kWh £845 £242 £1,087 £16,342 15.0 yrs £5,399
8 kW 6907 kWh 4144 kWh 2763 kWh £966 £276 £1,242 £18,376 14.8 yrs £6,470

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: £834, Upfront: £13,673, 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 1727 kWh 1209 kWh 518 kWh £282 £52 £334 £7,569 22.7 yrs £-898
3 kW 2590 kWh 1813 kWh 777 kWh £423 £78 £500 £9,604 19.2 yrs £403
4 kW 3454 kWh 2417 kWh 1036 kWh £564 £104 £667 £11,638 17.4 yrs £1,704
5 kW 4317 kWh 3022 kWh 1295 kWh £704 £130 £834 £13,673 16.4 yrs £3,005
6 kW 5180 kWh 3626 kWh 1554 kWh £845 £155 £1,001 £15,707 15.7 yrs £4,306
7 kW 6044 kWh 4231 kWh 1813 kWh £986 £181 £1,167 £17,742 15.2 yrs £5,608
8 kW 6907 kWh 4835 kWh 2072 kWh £1,127 £207 £1,334 £19,776 14.8 yrs £6,909

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: £851, Upfront: £15,423, Break-even: 18.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1727 kWh 1261 kWh 466 kWh £294 £47 £340 £9,319 27.4 yrs £-2,510
3 kW 2590 kWh 1891 kWh 699 kWh £441 £70 £511 £11,354 22.2 yrs £-1,140
4 kW 3454 kWh 2521 kWh 932 kWh £588 £93 £681 £13,388 19.7 yrs £230
5 kW 4317 kWh 3151 kWh 1166 kWh £735 £117 £851 £15,423 18.1 yrs £1,600
6 kW 5180 kWh 3782 kWh 1399 kWh £881 £140 £1,021 £17,457 17.1 yrs £2,970
7 kW 6044 kWh 4412 kWh 1632 kWh £1,028 £163 £1,192 £19,492 16.4 yrs £4,340
8 kW 6907 kWh 5042 kWh 1865 kWh £1,175 £186 £1,362 £21,526 15.8 yrs £5,710

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: £863, Upfront: £17,173, Break-even: 19.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1727 kWh 1295 kWh 432 kWh £302 £43 £345 £11,069 32.1 yrs £-4,168
3 kW 2590 kWh 1943 kWh 648 kWh £453 £65 £518 £13,104 25.3 yrs £-2,752
4 kW 3454 kWh 2590 kWh 863 kWh £604 £86 £690 £15,138 21.9 yrs £-1,336
5 kW 4317 kWh 3238 kWh 1079 kWh £755 £108 £863 £17,173 19.9 yrs £80
6 kW 5180 kWh 3885 kWh 1295 kWh £906 £130 £1,035 £19,207 18.6 yrs £1,496
7 kW 6044 kWh 4533 kWh 1511 kWh £1,057 £151 £1,208 £21,242 17.6 yrs £2,912
8 kW 6907 kWh 5180 kWh 1727 kWh £1,208 £173 £1,380 £23,276 16.9 yrs £4,328

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: £874, Upfront: £19,623, Break-even: 22.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1727 kWh 1330 kWh 397 kWh £310 £40 £350 £13,519 38.7 yrs £-6,526
3 kW 2590 kWh 1994 kWh 596 kWh £465 £60 £524 £15,554 29.7 yrs £-5,064
4 kW 3454 kWh 2659 kWh 794 kWh £620 £79 £699 £17,588 25.2 yrs £-3,602
5 kW 4317 kWh 3324 kWh 993 kWh £775 £99 £874 £19,623 22.4 yrs £-2,140
6 kW 5180 kWh 3989 kWh 1191 kWh £930 £119 £1,049 £21,657 20.6 yrs £-678
7 kW 6044 kWh 4654 kWh 1390 kWh £1,085 £139 £1,224 £23,692 19.4 yrs £784
8 kW 6907 kWh 5318 kWh 1589 kWh £1,240 £159 £1,399 £25,726 18.4 yrs £2,246

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 SA20

Figures below are tailored to SA20 — click through for full league tables.

Big-Roof Britain Rank #69 of 2182
6.8 kWp (UK avg 5.1 kWp)
~14 panels (≈430 W)
Solar Payback Index Rank #2538 of 2997
13.6 years (UK avg 12.6 years)
~£895 /yr • £12,207 upfront
Standing-Charge Drag Rank #1225 of 2997
21.5% (UK avg 24.6%) drag on savings
£193 fixed • ~£895 /yr value
Aspect Penalty View ranking →
East −17.5% West −18.0%
Typical output loss versus a south-facing roof (lower is better)

Seasonal solar output in SA20

Monthly generation per kilowatt of solar panels

kWh 27 Jan 44 Feb 76 Mar 105 Apr 112 May 108 Jun 105 Jul 93 Aug 80 Sep 54 Oct 35 Nov 24 Dec
Best month Worst month Winter (Dec–Feb) Other months

Winter output: 43.9% 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 32 kWh per month; the average month produces around 72 kWh. So a typical 4 kW home system would generate roughly 126 kWh in winter, or 288 kWh in an average month.

Your Area at a Glance

Your Electricity Rate
23.31p/kWh
Daily Fixed Charge
56.85p/day
Local Sunshine
863kWh/kW
A 1 kW system generates ~863 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: 72% • Flats: 6% • Bungalows: 21% Based on 869 properties

Coverage

Carmarthenshire (100%)

Areas Covered

Llandovery, Cilycwm, Llangadog, Manordeilo and Salem

Data Sources & Assumptions

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

Electricity rates: Ofgem price cap, Q1 2026

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

SA19 (Carmarthenshire)
≈14.1 km away
Local sunshine: ~894 kWh/kWp · +4% vs SA20
LD5 (Powys)
≈17.3 km away
Local sunshine: ~878 kWh/kWp · +2% vs SA20
LD4 (Powys)
≈21.1 km away
Local sunshine: ~903 kWh/kWp · +5% vs SA20
SA48 (Ceredigion)
≈24.1 km away
Local sunshine: ~888 kWh/kWp · +3% vs SA20
SA9 (Powys)
≈24.3 km away
Local sunshine: ~873 kWh/kWp · +1% vs SA20
SA18 (Carmarthenshire)
≈25.9 km away
Local sunshine: ~895 kWh/kWp · +4% vs SA20

Similar sunshine across the UK

BT69 (Mid Ulster)
~863 kWh/kWp · +0% vs SA20
DG14 (Dumfries and Galloway)
~863 kWh/kWp · -0% vs SA20
LL42 (Gwynedd)
~864 kWh/kWp · +0% vs SA20