Solar explained to clever people by people who are not trying to be clever
Home Regions
Insights
Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in SA18 (Carmarthenshire)

See if solar pays off for you in Carmarthenshire — 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
13.6 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£749
What you save every year
Profit Over 25 Years
£8,556
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 26.83p/kWh with a 51.69p/day standing charge. Your postcode’s south-facing sunshine yield is 895 kWh/kW — 73 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 895 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)
895 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: £749, Upfront: £10,173, Break-even: 13.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1791 kWh 716 kWh 1075 kWh £192 £107 £300 £4,069 13.6 yrs £1,924
3 kW 2686 kWh 1075 kWh 1612 kWh £288 £161 £449 £6,104 13.6 yrs £2,886
4 kW 3582 kWh 1433 kWh 2149 kWh £384 £215 £599 £8,138 13.6 yrs £3,848
5 kW 4477 kWh 1791 kWh 2686 kWh £480 £269 £749 £10,173 13.6 yrs £4,810
6 kW 5373 kWh 2149 kWh 3224 kWh £577 £322 £899 £12,207 13.6 yrs £5,772
7 kW 6268 kWh 2507 kWh 3761 kWh £673 £376 £1,049 £14,242 13.6 yrs £6,734
8 kW 7164 kWh 2865 kWh 4298 kWh £769 £430 £1,199 £16,276 13.6 yrs £7,696

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: £900, Upfront: £12,273, Break-even: 13.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1791 kWh 1075 kWh 716 kWh £288 £72 £360 £6,169 17.1 yrs £1,030
3 kW 2686 kWh 1612 kWh 1075 kWh £432 £107 £540 £8,204 15.2 yrs £2,594
4 kW 3582 kWh 2149 kWh 1433 kWh £577 £143 £720 £10,238 14.2 yrs £4,159
5 kW 4477 kWh 2686 kWh 1791 kWh £721 £179 £900 £12,273 13.6 yrs £5,724
6 kW 5373 kWh 3224 kWh 2149 kWh £865 £215 £1,080 £14,307 13.2 yrs £7,289
7 kW 6268 kWh 3761 kWh 2507 kWh £1,009 £251 £1,260 £16,342 13.0 yrs £8,854
8 kW 7164 kWh 4298 kWh 2865 kWh £1,153 £287 £1,440 £18,376 12.8 yrs £10,418

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: £975, Upfront: £13,673, 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 1791 kWh 1254 kWh 537 kWh £336 £54 £390 £7,569 19.4 yrs £232
3 kW 2686 kWh 1880 kWh 806 kWh £505 £81 £585 £9,604 16.4 yrs £2,099
4 kW 3582 kWh 2507 kWh 1075 kWh £673 £107 £780 £11,638 14.9 yrs £3,965
5 kW 4477 kWh 3134 kWh 1343 kWh £841 £134 £975 £13,673 14.0 yrs £5,831
6 kW 5373 kWh 3761 kWh 1612 kWh £1,009 £161 £1,170 £15,707 13.4 yrs £7,697
7 kW 6268 kWh 4388 kWh 1880 kWh £1,177 £188 £1,365 £17,742 13.0 yrs £9,563
8 kW 7164 kWh 5014 kWh 2149 kWh £1,345 £215 £1,560 £19,776 12.7 yrs £11,430

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: £998, Upfront: £15,423, Break-even: 15.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1791 kWh 1307 kWh 484 kWh £351 £48 £399 £9,319 23.3 yrs £-1,337
3 kW 2686 kWh 1961 kWh 725 kWh £526 £73 £599 £11,354 19.0 yrs £620
4 kW 3582 kWh 2615 kWh 967 kWh £702 £97 £798 £13,388 16.8 yrs £2,577
5 kW 4477 kWh 3268 kWh 1209 kWh £877 £121 £998 £15,423 15.5 yrs £4,533
6 kW 5373 kWh 3922 kWh 1451 kWh £1,052 £145 £1,197 £17,457 14.6 yrs £6,490
7 kW 6268 kWh 4576 kWh 1692 kWh £1,228 £169 £1,397 £19,492 14.0 yrs £8,446
8 kW 7164 kWh 5229 kWh 1934 kWh £1,403 £193 £1,596 £21,526 13.5 yrs £10,403

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: £1,013, Upfront: £17,173, Break-even: 17.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1791 kWh 1343 kWh 448 kWh £360 £45 £405 £11,069 27.3 yrs £-2,966
3 kW 2686 kWh 2015 kWh 672 kWh £541 £67 £608 £13,104 21.6 yrs £-949
4 kW 3582 kWh 2686 kWh 895 kWh £721 £90 £810 £15,138 18.7 yrs £1,068
5 kW 4477 kWh 3358 kWh 1119 kWh £901 £112 £1,013 £17,173 17.0 yrs £3,085
6 kW 5373 kWh 4029 kWh 1343 kWh £1,081 £134 £1,215 £19,207 15.8 yrs £5,101
7 kW 6268 kWh 4701 kWh 1567 kWh £1,261 £157 £1,418 £21,242 15.0 yrs £7,118
8 kW 7164 kWh 5373 kWh 1791 kWh £1,441 £179 £1,621 £23,276 14.4 yrs £9,135

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: £1,028, Upfront: £19,623, Break-even: 19.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1791 kWh 1379 kWh 412 kWh £370 £41 £411 £13,519 32.9 yrs £-5,296
3 kW 2686 kWh 2068 kWh 618 kWh £555 £62 £617 £15,554 25.2 yrs £-3,218
4 kW 3582 kWh 2758 kWh 824 kWh £740 £82 £822 £17,588 21.4 yrs £-1,141
5 kW 4477 kWh 3447 kWh 1030 kWh £925 £103 £1,028 £19,623 19.1 yrs £936
6 kW 5373 kWh 4137 kWh 1236 kWh £1,110 £124 £1,234 £21,657 17.6 yrs £3,013
7 kW 6268 kWh 4826 kWh 1442 kWh £1,295 £144 £1,439 £23,692 16.5 yrs £5,090
8 kW 7164 kWh 5516 kWh 1648 kWh £1,480 £165 £1,645 £25,726 15.6 yrs £7,168

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 SA18

Figures below are tailored to SA18 — click through for full league tables.

Big-Roof Britain Rank #605 of 2182
5.5 kWp (UK avg 5.1 kWp)
~12 panels (≈430 W)
Solar Payback Index Rank #2152 of 2997
11.8 years (UK avg 11.3 years)
~£862 /yr • £10,173 upfront
Standing-Charge Drag Rank #1815 of 2997
21.9% (UK avg 21.7%) drag on savings
£189 fixed • ~£862 /yr value

Your Area at a Glance

Your Electricity Rate
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
895kWh/kW
A 1 kW system generates ~895 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: 73% • Flats: 11% • Bungalows: 16% Based on 8,275 properties

Coverage

Carmarthenshire (86%)|Neath Port Talbot (12%)|Swansea (2%)

Areas Covered

Ammanford, Llandybie, Gwaun-Cae-Gurwen and Lower Brynamman, Saron, Garnant, Betws, Glanamman, Tycroes + 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.

Compare nearby areas

Nearby in South Wales

SA8 (Neath Port Talbot)
≈12.5 km away
Local sunshine: ~888 kWh/kWp · -1% vs SA18
SA14 (Carmarthenshire)
≈13.6 km away
Local sunshine: ~948 kWh/kWp · +6% vs SA18
SA99 (Swansea)
≈14.1 km away
Local sunshine: ~968 kWh/kWp · +8% vs SA18
SA9 (Powys)
≈14.4 km away
Local sunshine: ~873 kWh/kWp · -2% vs SA18
SA4 (Swansea)
≈14.5 km away
Local sunshine: ~961 kWh/kWp · +7% vs SA18
SA6 (Swansea)
≈14.5 km away
Local sunshine: ~968 kWh/kWp · +8% vs SA18

Similar sunshine across the UK

S33 (High Peak)
~896 kWh/kWp · +0% vs SA18
KY4 (Fife)
~896 kWh/kWp · +0% vs SA18
AB31 (Aberdeenshire)
~896 kWh/kWp · +0% vs SA18