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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in CF5 (Cardiff)

See if solar pays off for you in Cardiff — 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
11.9 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£857
What you save every year
Profit Over 25 Years
£11,245
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 1024 kWh/kW — 56 above 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 1024 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)
1024 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: £857, Upfront: £10,173, Break-even: 11.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2048 kWh 819 kWh 1229 kWh £220 £123 £343 £4,069 11.9 yrs £2,785
3 kW 3072 kWh 1229 kWh 1843 kWh £330 £184 £514 £6,104 11.9 yrs £4,177
4 kW 4096 kWh 1638 kWh 2458 kWh £440 £246 £685 £8,138 11.9 yrs £5,569
5 kW 5120 kWh 2048 kWh 3072 kWh £549 £307 £857 £10,173 11.9 yrs £6,961
6 kW 6144 kWh 2458 kWh 3686 kWh £659 £369 £1,028 £12,207 11.9 yrs £8,354
7 kW 7168 kWh 2867 kWh 4301 kWh £769 £430 £1,199 £14,242 11.9 yrs £9,746
8 kW 8192 kWh 3277 kWh 4915 kWh £879 £492 £1,371 £16,276 11.9 yrs £11,138

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: £1,029, Upfront: £12,273, Break-even: 11.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2048 kWh 1229 kWh 819 kWh £330 £82 £412 £6,169 15.0 yrs £2,063
3 kW 3072 kWh 1843 kWh 1229 kWh £495 £123 £617 £8,204 13.3 yrs £4,145
4 kW 4096 kWh 2458 kWh 1638 kWh £659 £164 £823 £10,238 12.4 yrs £6,227
5 kW 5120 kWh 3072 kWh 2048 kWh £824 £205 £1,029 £12,273 11.9 yrs £8,308
6 kW 6144 kWh 3686 kWh 2458 kWh £989 £246 £1,235 £14,307 11.6 yrs £10,390
7 kW 7168 kWh 4301 kWh 2867 kWh £1,154 £287 £1,441 £16,342 11.3 yrs £12,471
8 kW 8192 kWh 4915 kWh 3277 kWh £1,319 £328 £1,646 £18,376 11.2 yrs £14,553

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: £1,115, Upfront: £13,673, Break-even: 12.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2048 kWh 1434 kWh 614 kWh £385 £61 £446 £7,569 17.0 yrs £1,353
3 kW 3072 kWh 2150 kWh 922 kWh £577 £92 £669 £9,604 14.4 yrs £3,779
4 kW 4096 kWh 2867 kWh 1229 kWh £769 £123 £892 £11,638 13.0 yrs £6,205
5 kW 5120 kWh 3584 kWh 1536 kWh £962 £154 £1,115 £13,673 12.3 yrs £8,632
6 kW 6144 kWh 4301 kWh 1843 kWh £1,154 £184 £1,338 £15,707 11.7 yrs £11,058
7 kW 7168 kWh 5018 kWh 2150 kWh £1,346 £215 £1,561 £17,742 11.4 yrs £13,484
8 kW 8192 kWh 5735 kWh 2458 kWh £1,539 £246 £1,784 £19,776 11.1 yrs £15,911

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: £1,141, Upfront: £15,423, 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 2048 kWh 1495 kWh 553 kWh £401 £55 £456 £9,319 20.4 yrs £-191
3 kW 3072 kWh 2243 kWh 829 kWh £602 £83 £685 £11,354 16.6 yrs £2,339
4 kW 4096 kWh 2990 kWh 1106 kWh £802 £111 £913 £13,388 14.7 yrs £4,869
5 kW 5120 kWh 3738 kWh 1382 kWh £1,003 £138 £1,141 £15,423 13.5 yrs £7,399
6 kW 6144 kWh 4485 kWh 1659 kWh £1,203 £166 £1,369 £17,457 12.7 yrs £9,928
7 kW 7168 kWh 5233 kWh 1935 kWh £1,404 £194 £1,597 £19,492 12.2 yrs £12,458
8 kW 8192 kWh 5980 kWh 2212 kWh £1,605 £221 £1,826 £21,526 11.8 yrs £14,988

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: £1,158, Upfront: £17,173, 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 2048 kWh 1536 kWh 512 kWh £412 £51 £463 £11,069 23.9 yrs £-1,803
3 kW 3072 kWh 2304 kWh 768 kWh £618 £77 £695 £13,104 18.9 yrs £796
4 kW 4096 kWh 3072 kWh 1024 kWh £824 £102 £927 £15,138 16.3 yrs £3,395
5 kW 5120 kWh 3840 kWh 1280 kWh £1,030 £128 £1,158 £17,173 14.8 yrs £5,993
6 kW 6144 kWh 4608 kWh 1536 kWh £1,236 £154 £1,390 £19,207 13.8 yrs £8,592
7 kW 7168 kWh 5376 kWh 1792 kWh £1,442 £179 £1,622 £21,242 13.1 yrs £11,191
8 kW 8192 kWh 6144 kWh 2048 kWh £1,648 £205 £1,853 £23,276 12.6 yrs £13,789

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: £1,176, Upfront: £19,623, Break-even: 16.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2048 kWh 1577 kWh 471 kWh £423 £47 £470 £13,519 28.8 yrs £-4,115
3 kW 3072 kWh 2365 kWh 707 kWh £635 £71 £705 £15,554 22.1 yrs £-1,447
4 kW 4096 kWh 3154 kWh 942 kWh £846 £94 £940 £17,588 18.7 yrs £1,220
5 kW 5120 kWh 3942 kWh 1178 kWh £1,058 £118 £1,176 £19,623 16.7 yrs £3,888
6 kW 6144 kWh 4731 kWh 1413 kWh £1,269 £141 £1,411 £21,657 15.4 yrs £6,556
7 kW 7168 kWh 5519 kWh 1649 kWh £1,481 £165 £1,646 £23,692 14.4 yrs £9,223
8 kW 8192 kWh 6308 kWh 1884 kWh £1,692 £188 £1,881 £25,726 13.7 yrs £11,891

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 CF5

Figures below are tailored to CF5 — click through for full league tables.

Big-Roof Britain Rank #1368 of 2182
4.8 kWp (UK avg 5.1 kWp)
~10 panels (≈430 W)
Solar Payback Index Rank #305 of 2997
10.3 years (UK avg 11.3 years)
~£986 /yr • £10,173 upfront
Standing-Charge Drag Rank #1241 of 2997
19.1% (UK avg 21.7%) drag on savings
£189 fixed • ~£986 /yr value

Your Area at a Glance

Your Electricity Rate
26.83p/kWh
Daily Fixed Charge
51.69p/day
Local Sunshine
1024kWh/kW
A 1 kW system generates ~1024 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: 71% • Flats: 25% • Bungalows: 3% Based on 19,249 properties

Coverage

Cardiff (90%)|Vale of Glamorgan (10%)

Areas Covered

Canton, Fairwater, Ely, Llandaff, Caerau, Pentyrch and St Fagans, Wenvoe, St Nicholas and Llancarfan + 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

CF11 (Cardiff)
≈3.7 km away
Local sunshine: ~1,006 kWh/kWp · -2% vs CF5
CF91 (Cardiff)
≈3.7 km away
Local sunshine: ~1,009 kWh/kWp · -1% vs CF5
CF1 (Cardiff)
≈4.1 km away
Local sunshine: ~1,009 kWh/kWp · -1% vs CF5
CF10 (Cardiff)
≈4.5 km away
Local sunshine: ~1,009 kWh/kWp · -1% vs CF5
CF4 (Cardiff)
≈4.6 km away
Local sunshine: ~1,013 kWh/kWp · -1% vs CF5
CF95 (Cardiff)
≈4.7 km away
Local sunshine: ~1,009 kWh/kWp · -1% vs CF5

Similar sunshine across the UK

RM15 (Thurrock)
~1,024 kWh/kWp · -0% vs CF5
RH13 (Horsham)
~1,024 kWh/kWp · +0% vs CF5
SO53 (Eastleigh)
~1,024 kWh/kWp · -0% vs CF5