Independent solar numbers for your postcode using official UK data
Home Regions Guides Get quote
Insights
Big Roof Britain Solar Payback Index Standing Charge Drag Roof Direction Penalty Winter Solar Reality Seasonal Solar Output

Solar panel cost in Carmarthenshire (SA40)

See realistic solar installation costs, savings and payback for SA40 (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
15.0 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£815
What you save every year
Profit Over 25 Years
£8,160
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

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 886 kWh/kW — 82 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 886 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)
886 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: £679, Upfront: £10,173, Break-even: 15.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1772 kWh 709 kWh 1063 kWh £165 £106 £272 £4,069 15.0 yrs £1,362
3 kW 2658 kWh 1063 kWh 1595 kWh £248 £159 £407 £6,104 15.0 yrs £2,043
4 kW 3544 kWh 1418 kWh 2127 kWh £330 £213 £543 £8,138 15.0 yrs £2,724
5 kW 4430 kWh 1772 kWh 2658 kWh £413 £266 £679 £10,173 15.0 yrs £3,406
6 kW 5316 kWh 2127 kWh 3190 kWh £496 £319 £815 £12,207 15.0 yrs £4,087
7 kW 6202 kWh 2481 kWh 3721 kWh £578 £372 £950 £14,242 15.0 yrs £4,768
8 kW 7089 kWh 2835 kWh 4253 kWh £661 £425 £1,086 £16,276 15.0 yrs £5,449

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: £797, Upfront: £12,273, 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 1772 kWh 1063 kWh 709 kWh £248 £71 £319 £6,169 19.4 yrs £206
3 kW 2658 kWh 1595 kWh 1063 kWh £372 £106 £478 £8,204 17.2 yrs £1,359
4 kW 3544 kWh 2127 kWh 1418 kWh £496 £142 £637 £10,238 16.1 yrs £2,511
5 kW 4430 kWh 2658 kWh 1772 kWh £620 £177 £797 £12,273 15.4 yrs £3,664
6 kW 5316 kWh 3190 kWh 2127 kWh £744 £213 £956 £14,307 15.0 yrs £4,817
7 kW 6202 kWh 3721 kWh 2481 kWh £867 £248 £1,116 £16,342 14.6 yrs £5,970
8 kW 7089 kWh 4253 kWh 2835 kWh £991 £284 £1,275 £18,376 14.4 yrs £7,123

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: £856, Upfront: £13,673, Break-even: 16.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1772 kWh 1240 kWh 532 kWh £289 £53 £342 £7,569 22.1 yrs £-723
3 kW 2658 kWh 1861 kWh 797 kWh £434 £80 £513 £9,604 18.7 yrs £666
4 kW 3544 kWh 2481 kWh 1063 kWh £578 £106 £685 £11,638 17.0 yrs £2,055
5 kW 4430 kWh 3101 kWh 1329 kWh £723 £133 £856 £13,673 16.0 yrs £3,444
6 kW 5316 kWh 3721 kWh 1595 kWh £867 £159 £1,027 £15,707 15.3 yrs £4,832
7 kW 6202 kWh 4342 kWh 1861 kWh £1,012 £186 £1,198 £17,742 14.8 yrs £6,221
8 kW 7089 kWh 4962 kWh 2127 kWh £1,157 £213 £1,369 £19,776 14.4 yrs £7,610

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: £874, Upfront: £15,423, Break-even: 17.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1772 kWh 1294 kWh 478 kWh £302 £48 £349 £9,319 26.7 yrs £-2,331
3 kW 2658 kWh 1940 kWh 718 kWh £452 £72 £524 £11,354 21.7 yrs £-872
4 kW 3544 kWh 2587 kWh 957 kWh £603 £96 £699 £13,388 19.2 yrs £588
5 kW 4430 kWh 3234 kWh 1196 kWh £754 £120 £874 £15,423 17.7 yrs £2,047
6 kW 5316 kWh 3881 kWh 1435 kWh £905 £144 £1,048 £17,457 16.7 yrs £3,507
7 kW 6202 kWh 4528 kWh 1675 kWh £1,055 £167 £1,223 £19,492 15.9 yrs £4,966
8 kW 7089 kWh 5175 kWh 1914 kWh £1,206 £191 £1,398 £21,526 15.4 yrs £6,426

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: £885, Upfront: £17,173, Break-even: 19.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1772 kWh 1329 kWh 443 kWh £310 £44 £354 £11,069 31.3 yrs £-3,987
3 kW 2658 kWh 1994 kWh 665 kWh £465 £66 £531 £13,104 24.7 yrs £-2,480
4 kW 3544 kWh 2658 kWh 886 kWh £620 £89 £708 £15,138 21.4 yrs £-973
5 kW 4430 kWh 3323 kWh 1108 kWh £775 £111 £885 £17,173 19.4 yrs £533
6 kW 5316 kWh 3987 kWh 1329 kWh £929 £133 £1,062 £19,207 18.1 yrs £2,040
7 kW 6202 kWh 4652 kWh 1551 kWh £1,084 £155 £1,239 £21,242 17.1 yrs £3,547
8 kW 7089 kWh 5316 kWh 1772 kWh £1,239 £177 £1,416 £23,276 16.4 yrs £5,053

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: £897, Upfront: £19,623, Break-even: 21.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1772 kWh 1365 kWh 408 kWh £318 £41 £359 £13,519 37.7 yrs £-6,342
3 kW 2658 kWh 2047 kWh 611 kWh £477 £61 £538 £15,554 28.9 yrs £-4,788
4 kW 3544 kWh 2729 kWh 815 kWh £636 £82 £718 £17,588 24.5 yrs £-3,235
5 kW 4430 kWh 3411 kWh 1019 kWh £795 £102 £897 £19,623 21.9 yrs £-1,681
6 kW 5316 kWh 4094 kWh 1223 kWh £954 £122 £1,077 £21,657 20.1 yrs £-127
7 kW 6202 kWh 4776 kWh 1427 kWh £1,113 £143 £1,256 £23,692 18.9 yrs £1,427
8 kW 7089 kWh 5458 kWh 1630 kWh £1,272 £163 £1,435 £25,726 17.9 yrs £2,981

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 SA40

Figures below are tailored to SA40 — click through for full league tables.

Big-Roof Britain Rank #90 of 2182
6.7 kWp (UK avg 5.1 kWp)
~14 panels (≈430 W)
Solar Payback Index Rank #2338 of 2997
13.3 years (UK avg 12.6 years)
~£918 /yr • £12,207 upfront
Standing-Charge Drag Rank #1138 of 2997
21.0% (UK avg 24.6%) drag on savings
£193 fixed • ~£918 /yr value
Aspect Penalty View ranking →
East −18.2% West −18.9%
Typical output loss versus a south-facing roof (lower is better)

Seasonal solar output in SA40

Monthly generation per kilowatt of solar panels

kWh 29 Jan 46 Feb 78 Mar 107 Apr 114 May 111 Jun 106 Jul 97 Aug 81 Sep 55 Oct 37 Nov 25 Dec
Best month Worst month Winter (Dec–Feb) Other months

Winter output: 45.0% 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 33 kWh per month; the average month produces around 74 kWh. So a typical 4 kW home system would generate roughly 133 kWh in winter, or 295 kWh in an average month.

Your Area at a Glance

Your Electricity Rate
23.31p/kWh
Daily Fixed Charge
56.85p/day
Local Sunshine
886kWh/kW
A 1 kW system generates ~886 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: 68% • Flats: 5% • Bungalows: 27% Based on 944 properties

Coverage

Carmarthenshire (52%)|Ceredigion (48%)

Areas Covered

Llanybydder, Llanwenog, Lampeter, Llanfihangel-ar-Arth, Llannarth, Llandysilio and Llangrannog

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

SA48 (Ceredigion)
≈7.4 km away
Local sunshine: ~888 kWh/kWp · +0% vs SA40
SA39 (Carmarthenshire)
≈8.8 km away
Local sunshine: ~888 kWh/kWp · +0% vs SA40
SA44 (Ceredigion)
≈13.8 km away
Local sunshine: ~893 kWh/kWp · +1% vs SA40
SA47 (Ceredigion)
≈16.3 km away
Local sunshine: ~921 kWh/kWp · +4% vs SA40
SA46 (Ceredigion)
≈19.5 km away
Local sunshine: ~927 kWh/kWp · +5% vs SA40
SA45 (Ceredigion)
≈20.2 km away
Local sunshine: ~909 kWh/kWp · +3% vs SA40

Similar sunshine across the UK

KA8 (South Ayrshire)
~886 kWh/kWp · +0% vs SA40
PH13 (Perth and Kinross)
~886 kWh/kWp · -0% vs SA40
LL33 (Conwy)
~886 kWh/kWp · +0% vs SA40