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

Solar Panels in TW6 (Hillingdon)

See if solar pays off for you in Hillingdon — 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
12.2 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£1,002
What you save every year
Profit Over 25 Years
£12,847
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 6.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1007 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)
1007 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: £835, Upfront: £10,173, Break-even: 12.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2013 kWh 805 kWh 1208 kWh £213 £121 £334 £4,069 12.2 yrs £2,612
3 kW 3020 kWh 1208 kWh 1812 kWh £320 £181 £501 £6,104 12.2 yrs £3,918
4 kW 4027 kWh 1611 kWh 2416 kWh £427 £242 £668 £8,138 12.2 yrs £5,224
5 kW 5033 kWh 2013 kWh 3020 kWh £533 £302 £835 £10,173 12.2 yrs £6,530
6 kW 6040 kWh 2416 kWh 3624 kWh £640 £362 £1,002 £12,207 12.2 yrs £7,837
7 kW 7047 kWh 2819 kWh 4228 kWh £746 £423 £1,169 £14,242 12.2 yrs £9,143
8 kW 8054 kWh 3221 kWh 4832 kWh £853 £483 £1,336 £16,276 12.2 yrs £10,449

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: £1,001, Upfront: £12,273, 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 2013 kWh 1208 kWh 805 kWh £320 £81 £400 £6,169 15.4 yrs £1,839
3 kW 3020 kWh 1812 kWh 1208 kWh £480 £121 £601 £8,204 13.7 yrs £3,809
4 kW 4027 kWh 2416 kWh 1611 kWh £640 £161 £801 £10,238 12.8 yrs £5,779
5 kW 5033 kWh 3020 kWh 2013 kWh £800 £201 £1,001 £12,273 12.3 yrs £7,749
6 kW 6040 kWh 3624 kWh 2416 kWh £960 £242 £1,201 £14,307 11.9 yrs £9,718
7 kW 7047 kWh 4228 kWh 2819 kWh £1,120 £282 £1,401 £16,342 11.7 yrs £11,688
8 kW 8054 kWh 4832 kWh 3221 kWh £1,280 £322 £1,602 £18,376 11.5 yrs £13,658

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: £1,084, Upfront: £13,673, 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 2013 kWh 1409 kWh 604 kWh £373 £60 £434 £7,569 17.5 yrs £1,103
3 kW 3020 kWh 2114 kWh 906 kWh £560 £91 £650 £9,604 14.8 yrs £3,405
4 kW 4027 kWh 2819 kWh 1208 kWh £746 £121 £867 £11,638 13.4 yrs £5,706
5 kW 5033 kWh 3523 kWh 1510 kWh £933 £151 £1,084 £13,673 12.6 yrs £8,008
6 kW 6040 kWh 4228 kWh 1812 kWh £1,120 £181 £1,301 £15,707 12.1 yrs £10,309
7 kW 7047 kWh 4933 kWh 2114 kWh £1,306 £211 £1,518 £17,742 11.7 yrs £12,611
8 kW 8054 kWh 5637 kWh 2416 kWh £1,493 £242 £1,734 £19,776 11.4 yrs £14,912

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: £1,109, Upfront: £15,423, Break-even: 13.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2013 kWh 1470 kWh 544 kWh £389 £54 £444 £9,319 21.0 yrs £-448
3 kW 3020 kWh 2205 kWh 815 kWh £584 £82 £665 £11,354 17.1 yrs £1,953
4 kW 4027 kWh 2940 kWh 1087 kWh £778 £109 £887 £13,388 15.1 yrs £4,354
5 kW 5033 kWh 3674 kWh 1359 kWh £973 £136 £1,109 £15,423 13.9 yrs £6,755
6 kW 6040 kWh 4409 kWh 1631 kWh £1,168 £163 £1,331 £17,457 13.1 yrs £9,156
7 kW 7047 kWh 5144 kWh 1903 kWh £1,362 £190 £1,552 £19,492 12.6 yrs £11,557
8 kW 8054 kWh 5879 kWh 2174 kWh £1,557 £217 £1,774 £21,526 12.1 yrs £13,958

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: £1,125, Upfront: £17,173, Break-even: 15.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2013 kWh 1510 kWh 503 kWh £400 £50 £450 £11,069 24.6 yrs £-2,065
3 kW 3020 kWh 2265 kWh 755 kWh £600 £76 £675 £13,104 19.4 yrs £402
4 kW 4027 kWh 3020 kWh 1007 kWh £800 £101 £900 £15,138 16.8 yrs £2,870
5 kW 5033 kWh 3775 kWh 1258 kWh £1,000 £126 £1,125 £17,173 15.3 yrs £5,337
6 kW 6040 kWh 4530 kWh 1510 kWh £1,200 £151 £1,351 £19,207 14.2 yrs £7,804
7 kW 7047 kWh 5285 kWh 1762 kWh £1,400 £176 £1,576 £21,242 13.5 yrs £10,272
8 kW 8054 kWh 6040 kWh 2013 kWh £1,599 £201 £1,801 £23,276 12.9 yrs £12,739

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: £1,142, Upfront: £19,623, Break-even: 17.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2013 kWh 1550 kWh 463 kWh £411 £46 £457 £13,519 29.6 yrs £-4,382
3 kW 3020 kWh 2325 kWh 695 kWh £616 £69 £685 £15,554 22.7 yrs £-1,849
4 kW 4027 kWh 3101 kWh 926 kWh £821 £93 £914 £17,588 19.3 yrs £685
5 kW 5033 kWh 3876 kWh 1158 kWh £1,026 £116 £1,142 £19,623 17.2 yrs £3,219
6 kW 6040 kWh 4651 kWh 1389 kWh £1,232 £139 £1,370 £21,657 15.8 yrs £5,753
7 kW 7047 kWh 5426 kWh 1621 kWh £1,437 £162 £1,599 £23,692 14.8 yrs £8,286
8 kW 8054 kWh 6201 kWh 1852 kWh £1,642 £185 £1,827 £25,726 14.1 yrs £10,820

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
26.48p/kWh
Daily Fixed Charge
44.62p/day
Local Sunshine
1007kWh/kW
A 1 kW system generates ~1007 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

No EPC data available for this outcode

Coverage

Hillingdon (97%)|Hounslow (2%)|Spelthorne (1%)

Areas Covered

Heathrow Villages, Hounslow Central, Sunbury East, Hounslow West, Stanwell North, Cranford

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.