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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in SP5 (Wiltshire)

See if solar pays off for you in Wiltshire — 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
12.0 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£1,015
What you save every year
Profit Over 25 Years
£13,165
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 Southern, the current unit rate is 26.48p/kWh with a 44.62p/day standing charge. Your postcode’s south-facing sunshine yield is 1019 kWh/kW — 18 above the regional median (1001).

Read the full story

A typical roof here lands around 6.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1019 kWh per year on a south-facing roof. We value self-used electricity at 26.5p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
26.5p/kWh
Standing charge
44.6p/day
Sunshine yield (south)
1019 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: £846, Upfront: £10,173, Break-even: 12.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2039 kWh 816 kWh 1223 kWh £216 £122 £338 £4,069 12.0 yrs £2,697
3 kW 3058 kWh 1223 kWh 1835 kWh £324 £183 £507 £6,104 12.0 yrs £4,045
4 kW 4078 kWh 1631 kWh 2447 kWh £432 £245 £677 £8,138 12.0 yrs £5,393
5 kW 5097 kWh 2039 kWh 3058 kWh £540 £306 £846 £10,173 12.0 yrs £6,742
6 kW 6117 kWh 2447 kWh 3670 kWh £648 £367 £1,015 £12,207 12.0 yrs £8,090
7 kW 7136 kWh 2854 kWh 4282 kWh £756 £428 £1,184 £14,242 12.0 yrs £9,439
8 kW 8155 kWh 3262 kWh 4893 kWh £864 £489 £1,353 £16,276 12.0 yrs £10,787

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: £1,014, Upfront: £12,273, Break-even: 12.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2039 kWh 1223 kWh 816 kWh £324 £82 £405 £6,169 15.2 yrs £1,941
3 kW 3058 kWh 1835 kWh 1223 kWh £486 £122 £608 £8,204 13.5 yrs £3,961
4 kW 4078 kWh 2447 kWh 1631 kWh £648 £163 £811 £10,238 12.6 yrs £5,981
5 kW 5097 kWh 3058 kWh 2039 kWh £810 £204 £1,014 £12,273 12.1 yrs £8,002
6 kW 6117 kWh 3670 kWh 2447 kWh £972 £245 £1,216 £14,307 11.8 yrs £10,022
7 kW 7136 kWh 4282 kWh 2854 kWh £1,134 £285 £1,419 £16,342 11.5 yrs £12,043
8 kW 8155 kWh 4893 kWh 3262 kWh £1,296 £326 £1,622 £18,376 11.3 yrs £14,063

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: £1,098, Upfront: £13,673, Break-even: 12.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2039 kWh 1427 kWh 612 kWh £378 £61 £439 £7,569 17.2 yrs £1,213
3 kW 3058 kWh 2141 kWh 917 kWh £567 £92 £659 £9,604 14.6 yrs £3,569
4 kW 4078 kWh 2854 kWh 1223 kWh £756 £122 £878 £11,638 13.3 yrs £5,926
5 kW 5097 kWh 3568 kWh 1529 kWh £945 £153 £1,098 £13,673 12.5 yrs £8,282
6 kW 6117 kWh 4282 kWh 1835 kWh £1,134 £183 £1,317 £15,707 11.9 yrs £10,638
7 kW 7136 kWh 4995 kWh 2141 kWh £1,323 £214 £1,537 £17,742 11.5 yrs £12,995
8 kW 8155 kWh 5709 kWh 2447 kWh £1,512 £245 £1,756 £19,776 11.3 yrs £15,351

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: £1,123, Upfront: £15,423, Break-even: 13.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2039 kWh 1488 kWh 550 kWh £394 £55 £449 £9,319 20.7 yrs £-336
3 kW 3058 kWh 2233 kWh 826 kWh £591 £83 £674 £11,354 16.9 yrs £2,122
4 kW 4078 kWh 2977 kWh 1101 kWh £788 £110 £898 £13,388 14.9 yrs £4,579
5 kW 5097 kWh 3721 kWh 1376 kWh £985 £138 £1,123 £15,423 13.7 yrs £7,036
6 kW 6117 kWh 4465 kWh 1651 kWh £1,182 £165 £1,348 £17,457 13.0 yrs £9,493
7 kW 7136 kWh 5209 kWh 1927 kWh £1,379 £193 £1,572 £19,492 12.4 yrs £11,950
8 kW 8155 kWh 5953 kWh 2202 kWh £1,576 £220 £1,797 £21,526 12.0 yrs £14,407

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: £1,140, Upfront: £17,173, Break-even: 15.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2039 kWh 1529 kWh 510 kWh £405 £51 £456 £11,069 24.3 yrs £-1,951
3 kW 3058 kWh 2294 kWh 765 kWh £607 £76 £684 £13,104 19.2 yrs £573
4 kW 4078 kWh 3058 kWh 1019 kWh £810 £102 £912 £15,138 16.6 yrs £3,098
5 kW 5097 kWh 3823 kWh 1274 kWh £1,012 £127 £1,140 £17,173 15.1 yrs £5,622
6 kW 6117 kWh 4587 kWh 1529 kWh £1,215 £153 £1,368 £19,207 14.0 yrs £8,146
7 kW 7136 kWh 5352 kWh 1784 kWh £1,417 £178 £1,596 £21,242 13.3 yrs £10,671
8 kW 8155 kWh 6117 kWh 2039 kWh £1,620 £204 £1,824 £23,276 12.8 yrs £13,195

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: £1,157, Upfront: £19,623, 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 2039 kWh 1570 kWh 469 kWh £416 £47 £463 £13,519 29.2 yrs £-4,267
3 kW 3058 kWh 2355 kWh 703 kWh £624 £70 £694 £15,554 22.4 yrs £-1,675
4 kW 4078 kWh 3140 kWh 938 kWh £831 £94 £925 £17,588 19.0 yrs £916
5 kW 5097 kWh 3925 kWh 1172 kWh £1,039 £117 £1,157 £19,623 17.0 yrs £3,508
6 kW 6117 kWh 4710 kWh 1407 kWh £1,247 £141 £1,388 £21,657 15.6 yrs £6,099
7 kW 7136 kWh 5495 kWh 1641 kWh £1,455 £164 £1,619 £23,692 14.6 yrs £8,691
8 kW 8155 kWh 6280 kWh 1876 kWh £1,663 £188 £1,850 £25,726 13.9 yrs £11,283

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 SP5

Figures below are tailored to SP5 — click through for full league tables.

Big-Roof Britain Rank #91 of 2182
6.6 kWp (UK avg 5.1 kWp)
~14 panels (≈430 W)
Solar Payback Index Rank #582 of 2997
10.5 years (UK avg 11.3 years)
~£1,166 /yr • £12,207 upfront
Standing-Charge Drag Rank #95 of 2997
14.0% (UK avg 21.7%) drag on savings
£163 fixed • ~£1,166 /yr value

Your Area at a Glance

Your Electricity Rate
26.48p/kWh
Daily Fixed Charge
44.62p/day
Local Sunshine
1019kWh/kW
A 1 kW system generates ~1019 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
6.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 71% • Flats: 5% • Bungalows: 23% Based on 5,529 properties

Coverage

Wiltshire (87%)|Dorset (7%)|Test Valley (6%)

Areas Covered

Alderbury & Whiteparish, Downton & Ebble Valley, Fovant & Chalke Valley, Redlynch & Landford, Winterslow & Upper Bourne Valley, Salisbury St Edmund's, Mid Test, Cranborne Chase + 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 Southern

SP1 (Wiltshire)
≈6.2 km away
Local sunshine: ~1,019 kWh/kWp · -0% vs SP5
SP2 (Wiltshire)
≈6.9 km away
Local sunshine: ~1,028 kWh/kWp · +1% vs SP5
SP6 (New Forest)
≈11.6 km away
Local sunshine: ~1,013 kWh/kWp · -1% vs SP5
SP4 (Wiltshire)
≈16.1 km away
Local sunshine: ~1,018 kWh/kWp · -0% vs SP5
SO51 (Test Valley)
≈17.3 km away
Local sunshine: ~1,015 kWh/kWp · -0% vs SP5
SO20 (Test Valley)
≈18.7 km away
Local sunshine: ~1,019 kWh/kWp · -0% vs SP5

Similar sunshine across the UK

PL22 (Cornwall)
~1,019 kWh/kWp · -0% vs SP5
NR23 (North Norfolk)
~1,019 kWh/kWp · -0% vs SP5
PE12 (South Holland)
~1,020 kWh/kWp · +0% vs SP5