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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in CF40 (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
13.0 years
After this, it's pure profit
Upfront Cost
£8,138
What you pay to get started
Annual Benefit
£624
What you save every year
Profit Over 25 Years
£7,465
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 933 kWh/kW — 36 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 933 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)
933 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: £780, Upfront: £10,173, Break-even: 13.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1865 kWh 746 kWh 1119 kWh £200 £112 £312 £4,069 13.0 yrs £2,172
3 kW 2798 kWh 1119 kWh 1679 kWh £300 £168 £468 £6,104 13.0 yrs £3,258
4 kW 3730 kWh 1492 kWh 2238 kWh £400 £224 £624 £8,138 13.0 yrs £4,344
5 kW 4663 kWh 1865 kWh 2798 kWh £500 £280 £780 £10,173 13.0 yrs £5,430
6 kW 5595 kWh 2238 kWh 3357 kWh £600 £336 £936 £12,207 13.0 yrs £6,516
7 kW 6528 kWh 2611 kWh 3917 kWh £701 £392 £1,092 £14,242 13.0 yrs £7,602
8 kW 7460 kWh 2984 kWh 4476 kWh £801 £448 £1,248 £16,276 13.0 yrs £8,688

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: £937, Upfront: £12,273, Break-even: 13.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1865 kWh 1119 kWh 746 kWh £300 £75 £375 £6,169 16.5 yrs £1,328
3 kW 2798 kWh 1679 kWh 1119 kWh £450 £112 £562 £8,204 14.6 yrs £3,041
4 kW 3730 kWh 2238 kWh 1492 kWh £600 £149 £750 £10,238 13.7 yrs £4,755
5 kW 4663 kWh 2798 kWh 1865 kWh £751 £187 £937 £12,273 13.1 yrs £6,469
6 kW 5595 kWh 3357 kWh 2238 kWh £901 £224 £1,124 £14,307 12.7 yrs £8,183
7 kW 6528 kWh 3917 kWh 2611 kWh £1,051 £261 £1,312 £16,342 12.5 yrs £9,897
8 kW 7460 kWh 4476 kWh 2984 kWh £1,201 £298 £1,499 £18,376 12.3 yrs £11,610

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: £1,016, Upfront: £13,673, Break-even: 13.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1865 kWh 1306 kWh 560 kWh £350 £56 £406 £7,569 18.6 yrs £555
3 kW 2798 kWh 1958 kWh 839 kWh £525 £84 £609 £9,604 15.8 yrs £2,583
4 kW 3730 kWh 2611 kWh 1119 kWh £701 £112 £812 £11,638 14.3 yrs £4,611
5 kW 4663 kWh 3264 kWh 1399 kWh £876 £140 £1,016 £13,673 13.5 yrs £6,638
6 kW 5595 kWh 3917 kWh 1679 kWh £1,051 £168 £1,219 £15,707 12.9 yrs £8,666
7 kW 6528 kWh 4569 kWh 1958 kWh £1,226 £196 £1,422 £17,742 12.5 yrs £10,694
8 kW 7460 kWh 5222 kWh 2238 kWh £1,401 £224 £1,625 £19,776 12.2 yrs £12,722

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: £1,039, Upfront: £15,423, Break-even: 14.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1865 kWh 1361 kWh 504 kWh £365 £50 £416 £9,319 22.4 yrs £-1,006
3 kW 2798 kWh 2042 kWh 755 kWh £548 £76 £623 £11,354 18.2 yrs £1,116
4 kW 3730 kWh 2723 kWh 1007 kWh £731 £101 £831 £13,388 16.1 yrs £3,237
5 kW 4663 kWh 3404 kWh 1259 kWh £913 £126 £1,039 £15,423 14.8 yrs £5,359
6 kW 5595 kWh 4084 kWh 1511 kWh £1,096 £151 £1,247 £17,457 14.0 yrs £7,481
7 kW 6528 kWh 4765 kWh 1762 kWh £1,278 £176 £1,455 £19,492 13.4 yrs £9,603
8 kW 7460 kWh 5446 kWh 2014 kWh £1,461 £201 £1,663 £21,526 12.9 yrs £11,725

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: £1,055, Upfront: £17,173, 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 1865 kWh 1399 kWh 466 kWh £375 £47 £422 £11,069 26.2 yrs £-2,631
3 kW 2798 kWh 2098 kWh 699 kWh £563 £70 £633 £13,104 20.7 yrs £-446
4 kW 3730 kWh 2798 kWh 933 kWh £751 £93 £844 £15,138 17.9 yrs £1,739
5 kW 4663 kWh 3497 kWh 1166 kWh £938 £117 £1,055 £17,173 16.3 yrs £3,923
6 kW 5595 kWh 4196 kWh 1399 kWh £1,126 £140 £1,266 £19,207 15.2 yrs £6,108
7 kW 6528 kWh 4896 kWh 1632 kWh £1,314 £163 £1,477 £21,242 14.4 yrs £8,292
8 kW 7460 kWh 5595 kWh 1865 kWh £1,501 £187 £1,688 £23,276 13.8 yrs £10,477

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: £1,070, Upfront: £19,623, Break-even: 18.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1865 kWh 1436 kWh 429 kWh £385 £43 £428 £13,519 31.6 yrs £-4,955
3 kW 2798 kWh 2154 kWh 643 kWh £578 £64 £642 £15,554 24.2 yrs £-2,708
4 kW 3730 kWh 2872 kWh 858 kWh £771 £86 £856 £17,588 20.5 yrs £-460
5 kW 4663 kWh 3590 kWh 1072 kWh £963 £107 £1,070 £19,623 18.3 yrs £1,787
6 kW 5595 kWh 4308 kWh 1287 kWh £1,156 £129 £1,285 £21,657 16.9 yrs £4,034
7 kW 6528 kWh 5026 kWh 1501 kWh £1,349 £150 £1,499 £23,692 15.8 yrs £6,282
8 kW 7460 kWh 5744 kWh 1716 kWh £1,541 £172 £1,713 £25,726 15.0 yrs £8,529

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 CF40

Figures below are tailored to CF40 — click through for full league tables.

Big-Roof Britain Rank #1671 of 2182
4.5 kWp (UK avg 5.1 kWp)
~9 panels (≈430 W)
Solar Payback Index Rank #1565 of 2997
11.3 years (UK avg 11.3 years)
~£718 /yr • £8,138 upfront
Standing-Charge Drag Rank #2394 of 2997
26.3% (UK avg 21.7%) drag on savings
£189 fixed • ~£718 /yr value

Your Area at a Glance

Your Electricity Rate
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
933kWh/kW
A 1 kW system generates ~933 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: 85% • Flats: 12% • Bungalows: 1% Based on 5,283 properties

Coverage

Rhondda Cynon Taf (100%)

Areas Covered

Pen-y-graig, Tonypandy, Cwm Clydach, Llwyn-y-pia, Trealaw, Tonyrefail West, 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

CF39 (Rhondda Cynon Taf)
≈2.9 km away
Local sunshine: ~929 kWh/kWp · -0% vs CF40
CF41 (Rhondda Cynon Taf)
≈3.7 km away
Local sunshine: ~927 kWh/kWp · -1% vs CF40
CF43 (Rhondda Cynon Taf)
≈4.2 km away
Local sunshine: ~921 kWh/kWp · -1% vs CF40
CF42 (Rhondda Cynon Taf)
≈6.6 km away
Local sunshine: ~884 kWh/kWp · -5% vs CF40
CF45 (Rhondda Cynon Taf)
≈8.1 km away
Local sunshine: ~898 kWh/kWp · -4% vs CF40
CF37 (Rhondda Cynon Taf)
≈8.1 km away
Local sunshine: ~940 kWh/kWp · +1% vs CF40

Similar sunshine across the UK

TD11 (Scottish Borders)
~933 kWh/kWp · +0% vs CF40
EH40 (East Lothian)
~932 kWh/kWp · -0% vs CF40
B17 (Birmingham)
~933 kWh/kWp · +0% vs CF40