Solar explained to clever people by people who are not trying to be clever

Solar Panels in SE22 (Southwark)

See if solar pays off for you in Southwark — 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
12.6 years
After this, it's pure profit
Upfront Cost
£6,104
What you pay to get started
Annual Benefit
£486
What you save every year
Profit Over 25 Years
£6,047
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

Read the full story

A typical roof here lands around 3.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 997 kWh per year on a south-facing roof. We value self-used electricity at 25.6p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
25.6p/kWh
Standing charge
46.1p/day
Sunshine yield (south)
997 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: £810, Upfront: £10,173, Break-even: 12.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1994 kWh 797 kWh 1196 kWh £204 £120 £324 £4,069 12.6 yrs £2,411
3 kW 2991 kWh 1196 kWh 1794 kWh £307 £179 £486 £6,104 12.6 yrs £3,617
4 kW 3987 kWh 1595 kWh 2392 kWh £409 £239 £648 £8,138 12.6 yrs £4,823
5 kW 4984 kWh 1994 kWh 2991 kWh £511 £299 £810 £10,173 12.6 yrs £6,028
6 kW 5981 kWh 2392 kWh 3589 kWh £613 £359 £972 £12,207 12.6 yrs £7,234
7 kW 6978 kWh 2791 kWh 4187 kWh £715 £419 £1,134 £14,242 12.6 yrs £8,440
8 kW 7975 kWh 3190 kWh 4785 kWh £818 £478 £1,296 £16,276 12.6 yrs £9,645

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: £966, Upfront: £12,273, Break-even: 12.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1994 kWh 1196 kWh 797 kWh £307 £80 £386 £6,169 16.0 yrs £1,558
3 kW 2991 kWh 1794 kWh 1196 kWh £460 £120 £580 £8,204 14.2 yrs £3,387
4 kW 3987 kWh 2392 kWh 1595 kWh £613 £159 £773 £10,238 13.3 yrs £5,216
5 kW 4984 kWh 2991 kWh 1994 kWh £766 £199 £966 £12,273 12.7 yrs £7,044
6 kW 5981 kWh 3589 kWh 2392 kWh £920 £239 £1,159 £14,307 12.3 yrs £8,873
7 kW 6978 kWh 4187 kWh 2791 kWh £1,073 £279 £1,352 £16,342 12.1 yrs £10,702
8 kW 7975 kWh 4785 kWh 3190 kWh £1,226 £319 £1,545 £18,376 11.9 yrs £12,531

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: £1,044, Upfront: £13,673, 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 1994 kWh 1396 kWh 598 kWh £358 £60 £418 £7,569 18.1 yrs £781
3 kW 2991 kWh 2093 kWh 897 kWh £537 £90 £626 £9,604 15.3 yrs £2,921
4 kW 3987 kWh 2791 kWh 1196 kWh £715 £120 £835 £11,638 13.9 yrs £5,062
5 kW 4984 kWh 3489 kWh 1495 kWh £894 £150 £1,044 £13,673 13.1 yrs £7,202
6 kW 5981 kWh 4187 kWh 1794 kWh £1,073 £179 £1,253 £15,707 12.5 yrs £9,343
7 kW 6978 kWh 4885 kWh 2093 kWh £1,252 £209 £1,461 £17,742 12.1 yrs £11,483
8 kW 7975 kWh 5582 kWh 2392 kWh £1,431 £239 £1,670 £19,776 11.8 yrs £13,624

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: £1,067, Upfront: £15,423, Break-even: 14.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1994 kWh 1455 kWh 538 kWh £373 £54 £427 £9,319 21.8 yrs £-782
3 kW 2991 kWh 2183 kWh 807 kWh £560 £81 £640 £11,354 17.7 yrs £1,452
4 kW 3987 kWh 2911 kWh 1077 kWh £746 £108 £854 £13,388 15.7 yrs £3,686
5 kW 4984 kWh 3639 kWh 1346 kWh £933 £135 £1,067 £15,423 14.5 yrs £5,920
6 kW 5981 kWh 4366 kWh 1615 kWh £1,119 £161 £1,281 £17,457 13.6 yrs £8,154
7 kW 6978 kWh 5094 kWh 1884 kWh £1,306 £188 £1,494 £19,492 13.0 yrs £10,388
8 kW 7975 kWh 5822 kWh 2153 kWh £1,492 £215 £1,707 £21,526 12.6 yrs £12,622

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: £1,083, Upfront: £17,173, Break-even: 15.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1994 kWh 1495 kWh 498 kWh £383 £50 £433 £11,069 25.6 yrs £-2,407
3 kW 2991 kWh 2243 kWh 748 kWh £575 £75 £650 £13,104 20.2 yrs £-111
4 kW 3987 kWh 2991 kWh 997 kWh £766 £100 £866 £15,138 17.5 yrs £2,185
5 kW 4984 kWh 3738 kWh 1246 kWh £958 £125 £1,083 £17,173 15.9 yrs £4,482
6 kW 5981 kWh 4486 kWh 1495 kWh £1,150 £150 £1,299 £19,207 14.8 yrs £6,778
7 kW 6978 kWh 5233 kWh 1744 kWh £1,341 £174 £1,516 £21,242 14.0 yrs £9,074
8 kW 7975 kWh 5981 kWh 1994 kWh £1,533 £199 £1,732 £23,276 13.4 yrs £11,370

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: £1,098, Upfront: £19,623, Break-even: 17.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1994 kWh 1535 kWh 459 kWh £393 £46 £439 £13,519 30.8 yrs £-4,733
3 kW 2991 kWh 2303 kWh 688 kWh £590 £69 £659 £15,554 23.6 yrs £-2,374
4 kW 3987 kWh 3070 kWh 917 kWh £787 £92 £879 £17,588 20.0 yrs £-15
5 kW 4984 kWh 3838 kWh 1146 kWh £984 £115 £1,098 £19,623 17.9 yrs £2,343
6 kW 5981 kWh 4605 kWh 1376 kWh £1,180 £138 £1,318 £21,657 16.4 yrs £4,702
7 kW 6978 kWh 5373 kWh 1605 kWh £1,377 £160 £1,538 £23,692 15.4 yrs £7,060
8 kW 7975 kWh 6141 kWh 1834 kWh £1,574 £183 £1,757 £25,726 14.6 yrs £9,419

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.

Your Area at a Glance

Your Electricity Rate
25.63p/kWh
Daily Fixed Charge
46.06p/day
Local Sunshine
997kWh/kW
A 1 kW system generates ~997 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
3.0kW
For houses & bungalows in this area

⚠️ This area is predominantly flats. Many residents require freeholder approval for solar installations. System size shown reflects houses and bungalows only.

Local Property Data

Property Types

Houses: 30% • Flats: 61% • Bungalows: 1% Based on 8,401 properties

Coverage

Southwark (100%)

Areas Covered

Goose Green, Dulwich Hill, Champion Hill, Dulwich Wood, Dulwich Village, Peckham Rye, Rye Lane

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.