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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in CF37 (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
12.9 years
After this, it's pure profit
Upfront Cost
£8,138
What you pay to get started
Annual Benefit
£629
What you save every year
Profit Over 25 Years
£7,588
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 940 kWh/kW — 29 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 940 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)
940 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: £786, Upfront: £10,173, Break-even: 12.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1880 kWh 752 kWh 1128 kWh £202 £113 £315 £4,069 12.9 yrs £2,221
3 kW 2820 kWh 1128 kWh 1692 kWh £303 £169 £472 £6,104 12.9 yrs £3,332
4 kW 3759 kWh 1504 kWh 2256 kWh £403 £226 £629 £8,138 12.9 yrs £4,443
5 kW 4699 kWh 1880 kWh 2820 kWh £504 £282 £786 £10,173 12.9 yrs £5,553
6 kW 5639 kWh 2256 kWh 3384 kWh £605 £338 £944 £12,207 12.9 yrs £6,664
7 kW 6579 kWh 2632 kWh 3947 kWh £706 £395 £1,101 £14,242 12.9 yrs £7,775
8 kW 7519 kWh 3008 kWh 4511 kWh £807 £451 £1,258 £16,276 12.9 yrs £8,885

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: £944, Upfront: £12,273, 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 1880 kWh 1128 kWh 752 kWh £303 £75 £378 £6,169 16.3 yrs £1,387
3 kW 2820 kWh 1692 kWh 1128 kWh £454 £113 £567 £8,204 14.5 yrs £3,130
4 kW 3759 kWh 2256 kWh 1504 kWh £605 £150 £756 £10,238 13.5 yrs £4,874
5 kW 4699 kWh 2820 kWh 1880 kWh £757 £188 £944 £12,273 13.0 yrs £6,617
6 kW 5639 kWh 3384 kWh 2256 kWh £908 £226 £1,133 £14,307 12.6 yrs £8,360
7 kW 6579 kWh 3947 kWh 2632 kWh £1,059 £263 £1,322 £16,342 12.4 yrs £10,104
8 kW 7519 kWh 4511 kWh 3008 kWh £1,210 £301 £1,511 £18,376 12.2 yrs £11,847

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: £1,024, Upfront: £13,673, Break-even: 13.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1880 kWh 1316 kWh 564 kWh £353 £56 £409 £7,569 18.5 yrs £620
3 kW 2820 kWh 1974 kWh 846 kWh £530 £85 £614 £9,604 15.6 yrs £2,679
4 kW 3759 kWh 2632 kWh 1128 kWh £706 £113 £819 £11,638 14.2 yrs £4,739
5 kW 4699 kWh 3290 kWh 1410 kWh £883 £141 £1,024 £13,673 13.4 yrs £6,799
6 kW 5639 kWh 3947 kWh 1692 kWh £1,059 £169 £1,228 £15,707 12.8 yrs £8,859
7 kW 6579 kWh 4605 kWh 1974 kWh £1,236 £197 £1,433 £17,742 12.4 yrs £10,918
8 kW 7519 kWh 5263 kWh 2256 kWh £1,412 £226 £1,638 £19,776 12.1 yrs £12,978

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: £1,047, Upfront: £15,423, Break-even: 14.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1880 kWh 1372 kWh 508 kWh £368 £51 £419 £9,319 22.2 yrs £-941
3 kW 2820 kWh 2058 kWh 761 kWh £552 £76 £628 £11,354 18.1 yrs £1,214
4 kW 3759 kWh 2744 kWh 1015 kWh £736 £102 £838 £13,388 16.0 yrs £3,369
5 kW 4699 kWh 3431 kWh 1269 kWh £920 £127 £1,047 £15,423 14.7 yrs £5,523
6 kW 5639 kWh 4117 kWh 1523 kWh £1,104 £152 £1,257 £17,457 13.9 yrs £7,678
7 kW 6579 kWh 4803 kWh 1776 kWh £1,289 £178 £1,466 £19,492 13.3 yrs £9,833
8 kW 7519 kWh 5489 kWh 2030 kWh £1,473 £203 £1,676 £21,526 12.8 yrs £11,987

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: £1,063, Upfront: £17,173, Break-even: 16.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1880 kWh 1410 kWh 470 kWh £378 £47 £425 £11,069 26.0 yrs £-2,564
3 kW 2820 kWh 2115 kWh 705 kWh £567 £70 £638 £13,104 20.5 yrs £-346
4 kW 3759 kWh 2820 kWh 940 kWh £757 £94 £850 £15,138 17.8 yrs £1,872
5 kW 4699 kWh 3525 kWh 1175 kWh £946 £117 £1,063 £17,173 16.2 yrs £4,090
6 kW 5639 kWh 4229 kWh 1410 kWh £1,135 £141 £1,276 £19,207 15.1 yrs £6,308
7 kW 6579 kWh 4934 kWh 1645 kWh £1,324 £164 £1,488 £21,242 14.3 yrs £8,526
8 kW 7519 kWh 5639 kWh 1880 kWh £1,513 £188 £1,701 £23,276 13.7 yrs £10,743

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: £1,079, Upfront: £19,623, Break-even: 18.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1880 kWh 1447 kWh 432 kWh £388 £43 £432 £13,519 31.3 yrs £-4,888
3 kW 2820 kWh 2171 kWh 649 kWh £583 £65 £647 £15,554 24.0 yrs £-2,606
4 kW 3759 kWh 2895 kWh 865 kWh £777 £86 £863 £17,588 20.4 yrs £-325
5 kW 4699 kWh 3618 kWh 1081 kWh £971 £108 £1,079 £19,623 18.2 yrs £1,956
6 kW 5639 kWh 4342 kWh 1297 kWh £1,165 £130 £1,295 £21,657 16.7 yrs £4,237
7 kW 6579 kWh 5066 kWh 1513 kWh £1,359 £151 £1,510 £23,692 15.7 yrs £6,518
8 kW 7519 kWh 5790 kWh 1729 kWh £1,553 £173 £1,726 £25,726 14.9 yrs £8,800

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 CF37

Figures below are tailored to CF37 — click through for full league tables.

Big-Roof Britain Rank #1650 of 2182
4.6 kWp (UK avg 5.1 kWp)
~10 panels (≈430 W)
Solar Payback Index Rank #1509 of 2997
11.2 years (UK avg 11.3 years)
~£724 /yr • £8,138 upfront
Standing-Charge Drag Rank #2387 of 2997
26.1% (UK avg 21.7%) drag on savings
£189 fixed • ~£724 /yr value

Your Area at a Glance

Your Electricity Rate
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
940kWh/kW
A 1 kW system generates ~940 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: 78% • Flats: 18% • Bungalows: 3% Based on 10,557 properties

Coverage

Rhondda Cynon Taf (100%)

Areas Covered

Graig and Pontypridd West, Pontypridd Town, Treforest, Trallwng, Ynysybwl, Hawthorn and Lower Rhydfelen, Rhydfelen Central, Cilfynydd + 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

CF38 (Rhondda Cynon Taf)
≈4.5 km away
Local sunshine: ~969 kWh/kWp · +3% vs CF37
CF39 (Rhondda Cynon Taf)
≈5.5 km away
Local sunshine: ~929 kWh/kWp · -1% vs CF37
CF46 (Merthyr Tydfil)
≈7.3 km away
Local sunshine: ~939 kWh/kWp · -0% vs CF37
CF8 (Caerphilly)
≈7.5 km away
Local sunshine: ~988 kWh/kWp · +5% vs CF37
CF83 (Caerphilly)
≈7.9 km away
Local sunshine: ~988 kWh/kWp · +5% vs CF37
CF40 (Rhondda Cynon Taf)
≈8.1 km away
Local sunshine: ~933 kWh/kWp · -1% vs CF37

Similar sunshine across the UK

B31 (Birmingham)
~940 kWh/kWp · +0% vs CF37
YO62 (North Yorkshire)
~940 kWh/kWp · +0% vs CF37
B29 (Birmingham)
~940 kWh/kWp · +0% vs CF37