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Solar panel cost in Westminster (SW1W)

See realistic solar installation costs, savings and payback for SW1W (Westminster) in under a minute using official UK data. Start with the calculator, then get a no-obligation quote from an MCS-certified installer. You can also ask the SolarByPostcode assistant to sanity-check your roof, bills and plans.

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
11.1 years
After this, it's pure profit
Upfront Cost
£5,481
What you pay to get started
Annual Benefit
£492
What you save every year
Profit Over 25 Years
£6,811
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: The official cost per kW is lower above 4 kW, so a 5–6 kW system can pay back a little faster than a 3–4 kW system on otherwise identical assumptions.
  • 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

Panel costs: Uses March 2026 TIC mean installation costs: £1,827/kW up to 4 kW and £1,628/kW above 4 kW.

Other costs: Battery prices are modelled at £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 London, the current unit rate is 26.35p/kWh with a 44.78p/day standing charge. Your postcode’s south-facing sunshine yield is 991 kWh/kW — 0 above the regional median (991).

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 991 kWh per year on a south-facing roof. We value self-used electricity at 26.4p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
26.4p/kWh
Standing charge
44.8p/day
Sunshine yield (south)
991 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: £819, Upfront: £9,134, Break-even: 11.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1982 kWh 793 kWh 1189 kWh £209 £119 £328 £3,654 11.1 yrs £2,902
3 kW 2973 kWh 1189 kWh 1784 kWh £313 £178 £492 £5,481 11.1 yrs £4,353
4 kW 3963 kWh 1585 kWh 2378 kWh £418 £238 £656 £7,307 11.1 yrs £5,804
5 kW 4954 kWh 1982 kWh 2973 kWh £522 £297 £819 £9,134 11.1 yrs £7,254
6 kW 5945 kWh 2378 kWh 3567 kWh £627 £357 £983 £10,961 11.1 yrs £8,705
7 kW 6936 kWh 2774 kWh 4162 kWh £731 £416 £1,147 £12,788 11.1 yrs £10,156
8 kW 7927 kWh 3171 kWh 4756 kWh £835 £476 £1,311 £14,615 11.1 yrs £11,607

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

3 kWh battery 5 kW example → Annual benefit: £981, Upfront: £11,234, Break-even: 11.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1982 kWh 1189 kWh 793 kWh £313 £79 £393 £5,754 14.7 yrs £2,098
3 kW 2973 kWh 1784 kWh 1189 kWh £470 £119 £589 £7,581 12.9 yrs £4,197
4 kW 3963 kWh 2378 kWh 1585 kWh £627 £159 £785 £9,407 12.0 yrs £6,296
5 kW 4954 kWh 2973 kWh 1982 kWh £783 £198 £981 £11,234 11.4 yrs £8,395
6 kW 5945 kWh 3567 kWh 2378 kWh £940 £238 £1,178 £13,061 11.1 yrs £10,493
7 kW 6936 kWh 4162 kWh 2774 kWh £1,097 £277 £1,374 £14,888 10.8 yrs £12,592
8 kW 7927 kWh 4756 kWh 3171 kWh £1,253 £317 £1,570 £16,715 10.6 yrs £14,691

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

5 kWh battery 5 kW example → Annual benefit: £1,062, Upfront: £12,634, 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 1982 kWh 1387 kWh 595 kWh £366 £59 £425 £7,154 16.8 yrs £1,346
3 kW 2973 kWh 2081 kWh 892 kWh £548 £89 £637 £8,981 14.1 yrs £3,769
4 kW 3963 kWh 2774 kWh 1189 kWh £731 £119 £850 £10,807 12.7 yrs £6,192
5 kW 4954 kWh 3468 kWh 1486 kWh £914 £149 £1,062 £12,634 11.9 yrs £8,615
6 kW 5945 kWh 4162 kWh 1784 kWh £1,097 £178 £1,275 £14,461 11.3 yrs £11,037
7 kW 6936 kWh 4855 kWh 2081 kWh £1,279 £208 £1,487 £16,288 11.0 yrs £13,460
8 kW 7927 kWh 5549 kWh 2378 kWh £1,462 £238 £1,700 £18,115 10.7 yrs £15,883

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

7.5 kWh battery 5 kW example → Annual benefit: £1,087, Upfront: £14,384, Break-even: 13.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1982 kWh 1447 kWh 535 kWh £381 £54 £435 £8,904 20.5 yrs £-210
3 kW 2973 kWh 2170 kWh 803 kWh £572 £80 £652 £10,731 16.5 yrs £2,310
4 kW 3963 kWh 2893 kWh 1070 kWh £762 £107 £869 £12,557 14.4 yrs £4,830
5 kW 4954 kWh 3617 kWh 1338 kWh £953 £134 £1,087 £14,384 13.2 yrs £7,351
6 kW 5945 kWh 4340 kWh 1605 kWh £1,144 £161 £1,304 £16,211 12.4 yrs £9,871
7 kW 6936 kWh 5063 kWh 1873 kWh £1,334 £187 £1,521 £18,038 11.9 yrs £12,391
8 kW 7927 kWh 5787 kWh 2140 kWh £1,525 £214 £1,739 £19,865 11.4 yrs £14,911

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

10 kWh battery 5 kW example → Annual benefit: £1,103, Upfront: £16,134, Break-even: 14.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1982 kWh 1486 kWh 495 kWh £392 £50 £441 £10,654 24.1 yrs £-1,830
3 kW 2973 kWh 2229 kWh 743 kWh £587 £74 £662 £12,481 18.9 yrs £755
4 kW 3963 kWh 2973 kWh 991 kWh £783 £99 £882 £14,307 16.2 yrs £3,340
5 kW 4954 kWh 3716 kWh 1239 kWh £979 £124 £1,103 £16,134 14.6 yrs £5,925
6 kW 5945 kWh 4459 kWh 1486 kWh £1,175 £149 £1,324 £17,961 13.6 yrs £8,510
7 kW 6936 kWh 5202 kWh 1734 kWh £1,371 £173 £1,544 £19,788 12.8 yrs £11,094
8 kW 7927 kWh 5945 kWh 1982 kWh £1,567 £198 £1,765 £21,615 12.2 yrs £13,679

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, battery £/kWh = 700.

13.5 kWh battery 5 kW example → Annual benefit: £1,119, Upfront: £18,584, Break-even: 16.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1982 kWh 1526 kWh 456 kWh £402 £46 £448 £13,104 29.3 yrs £-4,151
3 kW 2973 kWh 2289 kWh 684 kWh £603 £68 £671 £14,931 22.2 yrs £-1,501
4 kW 3963 kWh 3052 kWh 912 kWh £804 £91 £895 £16,757 18.7 yrs £1,149
5 kW 4954 kWh 3815 kWh 1139 kWh £1,005 £114 £1,119 £18,584 16.6 yrs £3,799
6 kW 5945 kWh 4578 kWh 1367 kWh £1,206 £137 £1,343 £20,411 15.2 yrs £6,448
7 kW 6936 kWh 5341 kWh 1595 kWh £1,407 £160 £1,567 £22,238 14.2 yrs £9,098
8 kW 7927 kWh 6104 kWh 1823 kWh £1,608 £182 £1,791 £24,065 13.4 yrs £11,748

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,827, 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.

Before you request quotes in Westminster

Use the numbers above to sanity-check installer quotes. The main things to compare are system size, battery assumptions, payback claims, MCS certification, DNO paperwork and export assumptions.

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Understand DNO, G98 and G99 export limits

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Insights for SW1W

Figures below are tailored to SW1W — click through for full league tables.

Solar Payback Index Rank #988 of 2996
9.9 years (UK avg 10.8 years)
~£983 /yr • £9,767 upfront
Standing-Charge Drag Rank #100 of 2996
16.6% (UK avg 26.6%) drag on savings
£163 fixed • ~£983 /yr value
Aspect Penalty View ranking →
East −22.0% West −19.4%
Typical output loss versus a south-facing roof (lower is better)

Seasonal solar output in SW1W

Monthly generation per kilowatt of solar panels

kWh 40 Jan 51 Feb 84 Mar 111 Apr 117 May 119 Jun 120 Jul 107 Aug 93 Sep 67 Oct 47 Nov 35 Dec
Best month Worst month Winter (Dec–Feb) Other months

Winter output: 51.0% of an average month (Dec–Feb)

Best / worst month: Jul / Dec

These figures show output per kilowatt (kW) of panels installed. In winter, a 1 kW system here produces about 42 kWh per month; the average month produces around 83 kWh. So a typical 4 kW home system would generate roughly 168 kWh in winter, or 330 kWh in an average month.

Your Area at a Glance

Your Electricity Rate
26.35p/kWh
Daily Fixed Charge
44.78p/day
Local Sunshine
991kWh/kW
A 1 kW system generates ~991 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
3.0kW
For eligible homes 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: 14% • Flats: 81% • Bungalows: 0% Based on 4,260 properties

Coverage

Westminster (86%)|Kensington and Chelsea (9%)|Wandsworth (5%)

Areas Covered

Knightsbridge & Belgravia, Vincent Square, Royal Hospital, St James's, Nine Elms, Pimlico North

Data Sources & Assumptions

Solar yield: PVGIS (EU Joint Research Centre), January 2025 data

Electricity rates: Ofgem price cap, Q3 2026

Installation costs: DESNZ/MCS data, March 2026 (TIC)

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 London

SW1X (Westminster)
≈0.7 km away
Local sunshine: ~992 kWh/kWp · +0% vs SW1W
SW1E (Westminster)
≈0.7 km away
Local sunshine: ~991 kWh/kWp · +0% vs SW1W
SW1V (Westminster)
≈0.8 km away
Local sunshine: ~991 kWh/kWp · +0% vs SW1W
SW1P (Westminster)
≈1.1 km away
Local sunshine: ~991 kWh/kWp · +0% vs SW1W
SW1H (Westminster)
≈1.2 km away
Local sunshine: ~991 kWh/kWp · -0% vs SW1W
SW3 (Kensington and Chelsea)
≈1.4 km away
Local sunshine: ~989 kWh/kWp · -0% vs SW1W

Similar sunshine across the UK

SN26 (Swindon)
~991 kWh/kWp · -0% vs SW1W
EN4 (Barnet)
~991 kWh/kWp · -0% vs SW1W
SM7 (Reigate and Banstead)
~991 kWh/kWp · +0% vs SW1W