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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in PO3 (Portsmouth)

See if solar pays off for you in Portsmouth — 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
11.2 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£909
What you save every year
Profit Over 25 Years
£12,553
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 1096 kWh/kW — 94 above the regional median (1001).

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 1096 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)
1096 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: £909, Upfront: £10,173, Break-even: 11.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2191 kWh 877 kWh 1315 kWh £232 £131 £364 £4,069 11.2 yrs £3,203
3 kW 3287 kWh 1315 kWh 1972 kWh £348 £197 £545 £6,104 11.2 yrs £4,805
4 kW 4383 kWh 1753 kWh 2630 kWh £464 £263 £727 £8,138 11.2 yrs £6,406
5 kW 5479 kWh 2191 kWh 3287 kWh £580 £329 £909 £10,173 11.2 yrs £8,008
6 kW 6574 kWh 2630 kWh 3945 kWh £696 £394 £1,091 £12,207 11.2 yrs £9,609
7 kW 7670 kWh 3068 kWh 4602 kWh £812 £460 £1,273 £14,242 11.2 yrs £11,211
8 kW 8766 kWh 3506 kWh 5259 kWh £928 £526 £1,454 £16,276 11.2 yrs £12,812

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: £1,090, Upfront: £12,273, Break-even: 11.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2191 kWh 1315 kWh 877 kWh £348 £88 £436 £6,169 14.2 yrs £2,548
3 kW 3287 kWh 1972 kWh 1315 kWh £522 £131 £654 £8,204 12.5 yrs £4,871
4 kW 4383 kWh 2630 kWh 1753 kWh £696 £175 £872 £10,238 11.7 yrs £7,195
5 kW 5479 kWh 3287 kWh 2191 kWh £870 £219 £1,090 £12,273 11.3 yrs £9,519
6 kW 6574 kWh 3945 kWh 2630 kWh £1,045 £263 £1,308 £14,307 10.9 yrs £11,843
7 kW 7670 kWh 4602 kWh 3068 kWh £1,219 £307 £1,525 £16,342 10.7 yrs £14,167
8 kW 8766 kWh 5259 kWh 3506 kWh £1,393 £351 £1,743 £18,376 10.5 yrs £16,491

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: £1,180, Upfront: £13,673, Break-even: 11.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2191 kWh 1534 kWh 657 kWh £406 £66 £472 £7,569 16.0 yrs £1,870
3 kW 3287 kWh 2301 kWh 986 kWh £609 £99 £708 £9,604 13.6 yrs £4,555
4 kW 4383 kWh 3068 kWh 1315 kWh £812 £131 £944 £11,638 12.3 yrs £7,240
5 kW 5479 kWh 3835 kWh 1644 kWh £1,016 £164 £1,180 £13,673 11.6 yrs £9,925
6 kW 6574 kWh 4602 kWh 1972 kWh £1,219 £197 £1,416 £15,707 11.1 yrs £12,610
7 kW 7670 kWh 5369 kWh 2301 kWh £1,422 £230 £1,652 £17,742 10.7 yrs £15,295
8 kW 8766 kWh 6136 kWh 2630 kWh £1,625 £263 £1,888 £19,776 10.5 yrs £17,980

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: £1,207, Upfront: £15,423, Break-even: 12.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2191 kWh 1600 kWh 592 kWh £424 £59 £483 £9,319 19.3 yrs £337
3 kW 3287 kWh 2400 kWh 888 kWh £635 £89 £724 £11,354 15.7 yrs £3,130
4 kW 4383 kWh 3200 kWh 1183 kWh £847 £118 £966 £13,388 13.9 yrs £5,923
5 kW 5479 kWh 3999 kWh 1479 kWh £1,059 £148 £1,207 £15,423 12.8 yrs £8,717
6 kW 6574 kWh 4799 kWh 1775 kWh £1,271 £178 £1,448 £17,457 12.1 yrs £11,510
7 kW 7670 kWh 5599 kWh 2071 kWh £1,483 £207 £1,690 £19,492 11.5 yrs £14,303
8 kW 8766 kWh 6399 kWh 2367 kWh £1,694 £237 £1,931 £21,526 11.1 yrs £17,097

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: £1,225, Upfront: £17,173, Break-even: 14.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2191 kWh 1644 kWh 548 kWh £435 £55 £490 £11,069 22.6 yrs £-1,269
3 kW 3287 kWh 2465 kWh 822 kWh £653 £82 £735 £13,104 17.8 yrs £1,597
4 kW 4383 kWh 3287 kWh 1096 kWh £870 £110 £980 £15,138 15.4 yrs £4,462
5 kW 5479 kWh 4109 kWh 1370 kWh £1,088 £137 £1,225 £17,173 14.0 yrs £7,328
6 kW 6574 kWh 4931 kWh 1644 kWh £1,306 £164 £1,470 £19,207 13.1 yrs £10,193
7 kW 7670 kWh 5753 kWh 1918 kWh £1,523 £192 £1,715 £21,242 12.4 yrs £13,059
8 kW 8766 kWh 6574 kWh 2191 kWh £1,741 £219 £1,960 £23,276 11.9 yrs £15,924

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: £1,243, Upfront: £19,623, Break-even: 15.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2191 kWh 1687 kWh 504 kWh £447 £50 £497 £13,519 27.2 yrs £-3,574
3 kW 3287 kWh 2531 kWh 756 kWh £670 £76 £746 £15,554 20.9 yrs £-637
4 kW 4383 kWh 3375 kWh 1008 kWh £894 £101 £994 £17,588 17.7 yrs £2,301
5 kW 5479 kWh 4219 kWh 1260 kWh £1,117 £126 £1,243 £19,623 15.8 yrs £5,239
6 kW 6574 kWh 5062 kWh 1512 kWh £1,340 £151 £1,492 £21,657 14.5 yrs £8,177
7 kW 7670 kWh 5906 kWh 1764 kWh £1,564 £176 £1,740 £23,692 13.6 yrs £11,114
8 kW 8766 kWh 6750 kWh 2016 kWh £1,787 £202 £1,989 £25,726 12.9 yrs £14,052

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 PO3

Figures below are tailored to PO3 — click through for full league tables.

Big-Roof Britain Rank #1597 of 2182
4.6 kWp (UK avg 5.1 kWp)
~10 panels (≈430 W)
Solar Payback Index Rank #102 of 2997
9.7 years (UK avg 11.3 years)
~£1,044 /yr • £10,173 upfront
Standing-Charge Drag Rank #514 of 2997
15.6% (UK avg 21.7%) drag on savings
£163 fixed • ~£1,044 /yr value

Your Area at a Glance

Your Electricity Rate
26.48p/kWh
Daily Fixed Charge
44.62p/day
Local Sunshine
1096kWh/kW
A 1 kW system generates ~1096 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: 70% • Flats: 27% • Bungalows: 0% Based on 4,917 properties

Coverage

Portsmouth (100%)

Areas Covered

Baffins, Copnor, Hilsea, Charles Dickens, Milton, Fratton

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

PO2 (Portsmouth)
≈1.3 km away
Local sunshine: ~1,096 kWh/kWp · +0% vs PO3
PO1 (Portsmouth)
≈2.6 km away
Local sunshine: ~1,084 kWh/kWp · -1% vs PO3
PO4 (Portsmouth)
≈2.6 km away
Local sunshine: ~1,084 kWh/kWp · -1% vs PO3
PO5 (Portsmouth)
≈3.3 km away
Local sunshine: ~1,084 kWh/kWp · -1% vs PO3
PO6 (Portsmouth)
≈3.5 km away
Local sunshine: ~1,090 kWh/kWp · -1% vs PO3
PO12 (Gosport)
≈6.2 km away
Local sunshine: ~1,072 kWh/kWp · -2% vs PO3

Similar sunshine across the UK

TR24 (Isles of Scilly)
~1,096 kWh/kWp · +0% vs PO3
CT12 (Thanet)
~1,094 kWh/kWp · -0% vs PO3
CO7 (Tendring)
~1,094 kWh/kWp · -0% vs PO3