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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in CF42 (Rhondda Cynon Taf)

See if solar pays off for you in Rhondda Cynon Taf — 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
13.8 years
After this, it's pure profit
Upfront Cost
£8,138
What you pay to get started
Annual Benefit
£591
What you save every year
Profit Over 25 Years
£6,649
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 26.83p/kWh with a 51.69p/day standing charge. Your postcode’s south-facing sunshine yield is 884 kWh/kW — 85 below the regional median (968).

Read the full story

A typical roof here lands around 4.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 884 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)
884 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: £739, Upfront: £10,173, Break-even: 13.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1767 kWh 707 kWh 1060 kWh £190 £106 £296 £4,069 13.8 yrs £1,846
3 kW 2651 kWh 1060 kWh 1591 kWh £285 £159 £444 £6,104 13.8 yrs £2,768
4 kW 3535 kWh 1414 kWh 2121 kWh £379 £212 £591 £8,138 13.8 yrs £3,691
5 kW 4419 kWh 1767 kWh 2651 kWh £474 £265 £739 £10,173 13.8 yrs £4,614
6 kW 5302 kWh 2121 kWh 3181 kWh £569 £318 £887 £12,207 13.8 yrs £5,537
7 kW 6186 kWh 2474 kWh 3712 kWh £664 £371 £1,035 £14,242 13.8 yrs £6,460
8 kW 7070 kWh 2828 kWh 4242 kWh £759 £424 £1,183 £16,276 13.8 yrs £7,382

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: £888, Upfront: £12,273, Break-even: 13.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1767 kWh 1060 kWh 707 kWh £285 £71 £355 £6,169 17.4 yrs £935
3 kW 2651 kWh 1591 kWh 1060 kWh £427 £106 £533 £8,204 15.4 yrs £2,453
4 kW 3535 kWh 2121 kWh 1414 kWh £569 £141 £710 £10,238 14.4 yrs £3,971
5 kW 4419 kWh 2651 kWh 1767 kWh £711 £177 £888 £12,273 13.8 yrs £5,489
6 kW 5302 kWh 3181 kWh 2121 kWh £854 £212 £1,066 £14,307 13.4 yrs £7,006
7 kW 6186 kWh 3712 kWh 2474 kWh £996 £247 £1,243 £16,342 13.1 yrs £8,524
8 kW 7070 kWh 4242 kWh 2828 kWh £1,138 £283 £1,421 £18,376 12.9 yrs £10,042

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: £962, Upfront: £13,673, 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 1767 kWh 1237 kWh 530 kWh £332 £53 £385 £7,569 19.7 yrs £130
3 kW 2651 kWh 1856 kWh 795 kWh £498 £80 £577 £9,604 16.6 yrs £1,946
4 kW 3535 kWh 2474 kWh 1060 kWh £664 £106 £770 £11,638 15.1 yrs £3,761
5 kW 4419 kWh 3093 kWh 1326 kWh £830 £133 £962 £13,673 14.2 yrs £5,576
6 kW 5302 kWh 3712 kWh 1591 kWh £996 £159 £1,155 £15,707 13.6 yrs £7,391
7 kW 6186 kWh 4330 kWh 1856 kWh £1,162 £186 £1,347 £17,742 13.2 yrs £9,206
8 kW 7070 kWh 4949 kWh 2121 kWh £1,328 £212 £1,540 £19,776 12.8 yrs £11,022

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: £985, Upfront: £15,423, Break-even: 15.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1767 kWh 1290 kWh 477 kWh £346 £48 £394 £9,319 23.7 yrs £-1,441
3 kW 2651 kWh 1935 kWh 716 kWh £519 £72 £591 £11,354 19.2 yrs £463
4 kW 3535 kWh 2580 kWh 954 kWh £692 £95 £788 £13,388 17.0 yrs £2,368
5 kW 4419 kWh 3226 kWh 1193 kWh £865 £119 £985 £15,423 15.7 yrs £4,272
6 kW 5302 kWh 3871 kWh 1432 kWh £1,039 £143 £1,182 £17,457 14.8 yrs £6,177
7 kW 6186 kWh 4516 kWh 1670 kWh £1,212 £167 £1,379 £19,492 14.1 yrs £8,081
8 kW 7070 kWh 5161 kWh 1909 kWh £1,385 £191 £1,576 £21,526 13.7 yrs £9,985

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: £1,000, Upfront: £17,173, Break-even: 17.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1767 kWh 1326 kWh 442 kWh £356 £44 £400 £11,069 27.7 yrs £-3,072
3 kW 2651 kWh 1988 kWh 663 kWh £533 £66 £600 £13,104 21.8 yrs £-1,108
4 kW 3535 kWh 2651 kWh 884 kWh £711 £88 £800 £15,138 18.9 yrs £856
5 kW 4419 kWh 3314 kWh 1105 kWh £889 £110 £1,000 £17,173 17.2 yrs £2,820
6 kW 5302 kWh 3977 kWh 1326 kWh £1,067 £133 £1,200 £19,207 16.0 yrs £4,784
7 kW 6186 kWh 4640 kWh 1547 kWh £1,245 £155 £1,399 £21,242 15.2 yrs £6,747
8 kW 7070 kWh 5302 kWh 1767 kWh £1,423 £177 £1,599 £23,276 14.6 yrs £8,711

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: £1,014, Upfront: £19,623, Break-even: 19.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1767 kWh 1361 kWh 407 kWh £365 £41 £406 £13,519 33.3 yrs £-5,403
3 kW 2651 kWh 2041 kWh 610 kWh £548 £61 £609 £15,554 25.6 yrs £-3,380
4 kW 3535 kWh 2722 kWh 813 kWh £730 £81 £812 £17,588 21.7 yrs £-1,356
5 kW 4419 kWh 3402 kWh 1016 kWh £913 £102 £1,014 £19,623 19.3 yrs £667
6 kW 5302 kWh 4083 kWh 1220 kWh £1,095 £122 £1,217 £21,657 17.8 yrs £2,691
7 kW 6186 kWh 4763 kWh 1423 kWh £1,278 £142 £1,420 £23,692 16.7 yrs £4,714
8 kW 7070 kWh 5444 kWh 1626 kWh £1,461 £163 £1,623 £25,726 15.8 yrs £6,737

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 CF42

Figures below are tailored to CF42 — click through for full league tables.

Big-Roof Britain Rank #1463 of 2182
4.7 kWp (UK avg 5.1 kWp)
~10 panels (≈430 W)
Solar Payback Index Rank #2297 of 2997
12.0 years (UK avg 11.3 years)
~£681 /yr • £8,138 upfront
Standing-Charge Drag Rank #2486 of 2997
27.7% (UK avg 21.7%) drag on savings
£189 fixed • ~£681 /yr value

Your Area at a Glance

Your Electricity Rate
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
884kWh/kW
A 1 kW system generates ~884 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
4.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 92% • Flats: 6% • Bungalows: 2% Based on 4,936 properties

Coverage

Rhondda Cynon Taf (100%)

Areas Covered

Treorchy, Treherbert, Porth

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

CF41 (Rhondda Cynon Taf)
≈2.9 km away
Local sunshine: ~927 kWh/kWp · +5% vs CF42
CF43 (Rhondda Cynon Taf)
≈5.0 km away
Local sunshine: ~921 kWh/kWp · +4% vs CF42
CF40 (Rhondda Cynon Taf)
≈6.6 km away
Local sunshine: ~933 kWh/kWp · +6% vs CF42
CF44 (Rhondda Cynon Taf)
≈7.5 km away
Local sunshine: ~903 kWh/kWp · +2% vs CF42
CF39 (Rhondda Cynon Taf)
≈9.5 km away
Local sunshine: ~929 kWh/kWp · +5% vs CF42
CF45 (Rhondda Cynon Taf)
≈10.2 km away
Local sunshine: ~898 kWh/kWp · +2% vs CF42

Similar sunshine across the UK

M33 (Trafford)
~884 kWh/kWp · -0% vs CF42
BT11 (Belfast)
~884 kWh/kWp · +0% vs CF42
CA3 (Cumberland)
~884 kWh/kWp · +0% vs CF42