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Solar panel cost in Carmarthenshire (SA31)

See realistic solar installation costs, savings and payback for SA31 (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
10.3 years
After this, it's pure profit
Upfront Cost
£8,139
What you pay to get started
Annual Benefit
£791
What you save every year
Profit Over 25 Years
£11,644
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: The official cost per kW is lower above 4 kW, so a 5–6 kW system can pay back a little faster than a 3–4 kW system on otherwise identical assumptions.
  • 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

Panel costs: Uses March 2026 TIC mean installation costs: £1,827/kW up to 4 kW and £1,628/kW above 4 kW.

Other costs: Battery prices are modelled at £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 26.33p/kWh with a 57.84p/day standing charge. Your postcode’s south-facing sunshine yield is 957 kWh/kW — 11 below the regional median (968).

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 957 kWh per year on a south-facing roof. We value self-used electricity at 26.3p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
26.3p/kWh
Standing charge
57.8p/day
Sunshine yield (south)
957 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: £791, Upfront: £8,139, Break-even: 10.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1915 kWh 766 kWh 1149 kWh £202 £115 £317 £3,256 10.3 yrs £3,075
3 kW 2872 kWh 1149 kWh 1723 kWh £302 £172 £475 £4,883 10.3 yrs £4,612
4 kW 3829 kWh 1532 kWh 2298 kWh £403 £230 £633 £6,511 10.3 yrs £6,150
5 kW 4787 kWh 1915 kWh 2872 kWh £504 £287 £791 £8,139 10.3 yrs £7,687
6 kW 5744 kWh 2298 kWh 3446 kWh £605 £345 £950 £9,767 10.3 yrs £9,225
7 kW 6701 kWh 2680 kWh 4021 kWh £706 £402 £1,108 £11,394 10.3 yrs £10,762
8 kW 7658 kWh 3063 kWh 4595 kWh £807 £460 £1,266 £13,022 10.3 yrs £12,300

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

3 kWh battery 5 kW example → Annual benefit: £948, Upfront: £10,239, Break-even: 10.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1915 kWh 1149 kWh 766 kWh £302 £77 £379 £5,356 14.1 yrs £2,226
3 kW 2872 kWh 1723 kWh 1149 kWh £454 £115 £569 £6,983 12.3 yrs £4,388
4 kW 3829 kWh 2298 kWh 1532 kWh £605 £153 £758 £8,611 11.4 yrs £6,551
5 kW 4787 kWh 2872 kWh 1915 kWh £756 £191 £948 £10,239 10.8 yrs £8,714
6 kW 5744 kWh 3446 kWh 2298 kWh £907 £230 £1,137 £11,867 10.4 yrs £10,877
7 kW 6701 kWh 4021 kWh 2680 kWh £1,059 £268 £1,327 £13,494 10.2 yrs £13,040
8 kW 7658 kWh 4595 kWh 3063 kWh £1,210 £306 £1,516 £15,122 10.0 yrs £15,202

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

5 kWh battery 5 kW example → Annual benefit: £1,026, Upfront: £11,639, 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 1915 kWh 1340 kWh 574 kWh £353 £57 £410 £6,756 16.5 yrs £1,451
3 kW 2872 kWh 2010 kWh 862 kWh £529 £86 £615 £8,383 13.6 yrs £3,926
4 kW 3829 kWh 2680 kWh 1149 kWh £706 £115 £821 £10,011 12.2 yrs £6,402
5 kW 4787 kWh 3351 kWh 1436 kWh £882 £144 £1,026 £11,639 11.3 yrs £8,877
6 kW 5744 kWh 4021 kWh 1723 kWh £1,059 £172 £1,231 £13,267 10.8 yrs £11,353
7 kW 6701 kWh 4691 kWh 2010 kWh £1,235 £201 £1,436 £14,894 10.4 yrs £13,828
8 kW 7658 kWh 5361 kWh 2298 kWh £1,412 £230 £1,641 £16,522 10.1 yrs £16,304

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

7.5 kWh battery 5 kW example → Annual benefit: £1,049, Upfront: £13,389, 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 1915 kWh 1398 kWh 517 kWh £368 £52 £420 £8,506 20.3 yrs £-111
3 kW 2872 kWh 2097 kWh 775 kWh £552 £78 £630 £10,133 16.1 yrs £2,458
4 kW 3829 kWh 2795 kWh 1034 kWh £736 £103 £839 £11,761 14.0 yrs £5,027
5 kW 4787 kWh 3494 kWh 1292 kWh £920 £129 £1,049 £13,389 12.8 yrs £7,596
6 kW 5744 kWh 4193 kWh 1551 kWh £1,104 £155 £1,259 £15,017 11.9 yrs £10,166
7 kW 6701 kWh 4892 kWh 1809 kWh £1,288 £181 £1,469 £16,644 11.3 yrs £12,735
8 kW 7658 kWh 5591 kWh 2068 kWh £1,472 £207 £1,679 £18,272 10.9 yrs £15,304

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

10 kWh battery 5 kW example → Annual benefit: £1,065, Upfront: £15,139, Break-even: 14.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1915 kWh 1436 kWh 479 kWh £378 £48 £426 £10,256 24.1 yrs £-1,736
3 kW 2872 kWh 2154 kWh 718 kWh £567 £72 £639 £11,883 18.6 yrs £895
4 kW 3829 kWh 2872 kWh 957 kWh £756 £96 £852 £13,511 15.9 yrs £3,527
5 kW 4787 kWh 3590 kWh 1197 kWh £945 £120 £1,065 £15,139 14.2 yrs £6,159
6 kW 5744 kWh 4308 kWh 1436 kWh £1,134 £144 £1,278 £16,767 13.1 yrs £8,791
7 kW 6701 kWh 5026 kWh 1675 kWh £1,323 £168 £1,491 £18,394 12.3 yrs £11,423
8 kW 7658 kWh 5744 kWh 1915 kWh £1,512 £191 £1,704 £20,022 11.8 yrs £14,054

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

13.5 kWh battery 5 kW example → Annual benefit: £1,081, Upfront: £17,589, Break-even: 16.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1915 kWh 1474 kWh 440 kWh £388 £44 £432 £12,706 29.4 yrs £-4,061
3 kW 2872 kWh 2211 kWh 661 kWh £582 £66 £648 £14,333 22.1 yrs £-1,367
4 kW 3829 kWh 2949 kWh 881 kWh £776 £88 £864 £15,961 18.5 yrs £1,327
5 kW 4787 kWh 3686 kWh 1101 kWh £970 £110 £1,081 £17,589 16.3 yrs £4,022
6 kW 5744 kWh 4423 kWh 1321 kWh £1,165 £132 £1,297 £19,217 14.8 yrs £6,716
7 kW 6701 kWh 5160 kWh 1541 kWh £1,359 £154 £1,513 £20,844 13.8 yrs £9,410
8 kW 7658 kWh 5897 kWh 1761 kWh £1,553 £176 £1,729 £22,472 13.0 yrs £12,105

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, 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.

Before you request quotes in Carmarthenshire

Use the numbers above to sanity-check installer quotes. The main things to compare are system size, battery assumptions, payback claims, MCS certification, DNO paperwork and export assumptions.

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Understand DNO, G98 and G99 export limits

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This is a practical sanity-check request, not an instant quote promise. The Blue Ape quote route above remains available if you already want installer introductions.

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Insights for SA31

Figures below are tailored to SA31 — click through for full league tables.

Big-Roof Britain Rank #1254 of 2182
4.9 kWp (UK avg 5.1 kWp)
~10 panels (≈430 W)
Solar Payback Index Rank #1421 of 2996
10.3 years (UK avg 10.8 years)
~£791 /yr • £8,139 upfront
Standing-Charge Drag Rank #1699 of 2996
26.7% (UK avg 26.6%) drag on savings
£211 fixed • ~£791 /yr value
Aspect Penalty View ranking →
East −19.1% West −20.2%
Typical output loss versus a south-facing roof (lower is better)

Seasonal solar output in SA31

Monthly generation per kilowatt of solar panels

kWh 35 Jan 51 Feb 84 Mar 113 Apr 121 May 119 Jun 114 Jul 104 Aug 86 Sep 60 Oct 41 Nov 30 Dec
Best month Worst month Winter (Dec–Feb) Other months

Winter output: 48.4% 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 39 kWh per month; the average month produces around 80 kWh. So a typical 4 kW home system would generate roughly 154 kWh in winter, or 319 kWh in an average month.

Your Area at a Glance

Your Electricity Rate
26.33p/kWh
Daily Fixed Charge
57.84p/day
Local Sunshine
957kWh/kW
A 1 kW system generates ~957 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: 64% • Flats: 22% • Bungalows: 12% Based on 5,408 properties

Coverage

Carmarthenshire (100%)

Areas Covered

Carmarthen Town North and South, Llangunnor, Carmarthen Town West, Abergwili, Llangyndeyrn, Trelech, St Clears and Llansteffan, Whitland

Data Sources & Assumptions

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

Electricity rates: Ofgem price cap, Q3 2026

Installation costs: DESNZ/MCS data, March 2026 (TIC)

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

SA32 (Carmarthenshire)
≈9.9 km away
Local sunshine: ~950 kWh/kWp · -1% vs SA31
SA33 (Carmarthenshire)
≈10.3 km away
Local sunshine: ~992 kWh/kWp · +4% vs SA31
SA17 (Carmarthenshire)
≈11.9 km away
Local sunshine: ~985 kWh/kWp · +3% vs SA31
SA39 (Carmarthenshire)
≈18.6 km away
Local sunshine: ~888 kWh/kWp · -7% vs SA31
SA16 (Carmarthenshire)
≈19.0 km away
Local sunshine: ~1,012 kWh/kWp · +6% vs SA31
SA34 (Carmarthenshire)
≈21.3 km away
Local sunshine: ~995 kWh/kWp · +4% vs SA31

Similar sunshine across the UK

LE7 (Charnwood)
~957 kWh/kWp · -0% vs SA31
B61 (Bromsgrove)
~957 kWh/kWp · +0% vs SA31
DE73 (Derby)
~957 kWh/kWp · -0% vs SA31