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

Solar Panels in L37 (Sefton)

See if solar pays off for you in Sefton — 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
12.3 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£993
What you save every year
Profit Over 25 Years
£12,623
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 969 kWh per year on a south-facing roof. We value self-used electricity at 27.7p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
27.7p/kWh
Standing charge
70.0p/day
Sunshine yield (south)
969 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: £828, Upfront: £10,173, 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 1937 kWh 775 kWh 1162 kWh £215 £116 £331 £4,069 12.3 yrs £2,552
3 kW 2906 kWh 1162 kWh 1744 kWh £322 £174 £497 £6,104 12.3 yrs £3,828
4 kW 3875 kWh 1550 kWh 2325 kWh £430 £232 £662 £8,138 12.3 yrs £5,104
5 kW 4844 kWh 1937 kWh 2906 kWh £537 £291 £828 £10,173 12.3 yrs £6,381
6 kW 5812 kWh 2325 kWh 3487 kWh £644 £349 £993 £12,207 12.3 yrs £7,657
7 kW 6781 kWh 2712 kWh 4069 kWh £752 £407 £1,159 £14,242 12.3 yrs £8,933
8 kW 7750 kWh 3100 kWh 4650 kWh £859 £465 £1,324 £16,276 12.3 yrs £10,209

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: £999, 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 1937 kWh 1162 kWh 775 kWh £322 £77 £400 £6,169 15.4 yrs £1,825
3 kW 2906 kWh 1744 kWh 1162 kWh £483 £116 £600 £8,204 13.7 yrs £3,788
4 kW 3875 kWh 2325 kWh 1550 kWh £644 £155 £799 £10,238 12.8 yrs £5,751
5 kW 4844 kWh 2906 kWh 1937 kWh £806 £194 £999 £12,273 12.3 yrs £7,714
6 kW 5812 kWh 3487 kWh 2325 kWh £967 £232 £1,199 £14,307 11.9 yrs £9,676
7 kW 6781 kWh 4069 kWh 2712 kWh £1,128 £271 £1,399 £16,342 11.7 yrs £11,639
8 kW 7750 kWh 4650 kWh 3100 kWh £1,289 £310 £1,599 £18,376 11.5 yrs £13,602

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: £1,085, 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 1937 kWh 1356 kWh 581 kWh £376 £58 £434 £7,569 17.4 yrs £1,112
3 kW 2906 kWh 2034 kWh 872 kWh £564 £87 £651 £9,604 14.8 yrs £3,418
4 kW 3875 kWh 2712 kWh 1162 kWh £752 £116 £868 £11,638 13.4 yrs £5,724
5 kW 4844 kWh 3390 kWh 1453 kWh £940 £145 £1,085 £13,673 12.6 yrs £8,030
6 kW 5812 kWh 4069 kWh 1744 kWh £1,128 £174 £1,302 £15,707 12.1 yrs £10,336
7 kW 6781 kWh 4747 kWh 2034 kWh £1,316 £203 £1,519 £17,742 11.7 yrs £12,642
8 kW 7750 kWh 5425 kWh 2325 kWh £1,504 £232 £1,736 £19,776 11.4 yrs £14,948

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: £1,111, 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 1937 kWh 1414 kWh 523 kWh £392 £52 £444 £9,319 21.0 yrs £-432
3 kW 2906 kWh 2121 kWh 785 kWh £588 £78 £667 £11,354 17.0 yrs £1,977
4 kW 3875 kWh 2829 kWh 1046 kWh £784 £105 £889 £13,388 15.1 yrs £4,386
5 kW 4844 kWh 3536 kWh 1308 kWh £980 £131 £1,111 £15,423 13.9 yrs £6,795
6 kW 5812 kWh 4243 kWh 1569 kWh £1,176 £157 £1,333 £17,457 13.1 yrs £9,204
7 kW 6781 kWh 4950 kWh 1831 kWh £1,372 £183 £1,555 £19,492 12.5 yrs £11,613
8 kW 7750 kWh 5657 kWh 2092 kWh £1,568 £209 £1,777 £21,526 12.1 yrs £14,022

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: £1,128, Upfront: £17,173, Break-even: 15.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1937 kWh 1453 kWh 484 kWh £403 £48 £451 £11,069 24.5 yrs £-2,045
3 kW 2906 kWh 2180 kWh 727 kWh £604 £73 £677 £13,104 19.4 yrs £433
4 kW 3875 kWh 2906 kWh 969 kWh £806 £97 £902 £15,138 16.8 yrs £2,911
5 kW 4844 kWh 3633 kWh 1211 kWh £1,007 £121 £1,128 £17,173 15.2 yrs £5,388
6 kW 5812 kWh 4359 kWh 1453 kWh £1,208 £145 £1,354 £19,207 14.2 yrs £7,866
7 kW 6781 kWh 5086 kWh 1695 kWh £1,410 £170 £1,579 £21,242 13.5 yrs £10,344
8 kW 7750 kWh 5812 kWh 1937 kWh £1,611 £194 £1,805 £23,276 12.9 yrs £12,822

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: £1,145, Upfront: £19,623, Break-even: 17.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1937 kWh 1492 kWh 446 kWh £414 £45 £458 £13,519 29.5 yrs £-4,357
3 kW 2906 kWh 2238 kWh 668 kWh £620 £67 £687 £15,554 22.6 yrs £-1,811
4 kW 3875 kWh 2984 kWh 891 kWh £827 £89 £916 £17,588 19.2 yrs £735
5 kW 4844 kWh 3729 kWh 1114 kWh £1,034 £111 £1,145 £19,623 17.1 yrs £3,282
6 kW 5812 kWh 4475 kWh 1337 kWh £1,241 £134 £1,374 £21,657 15.8 yrs £5,828
7 kW 6781 kWh 5221 kWh 1560 kWh £1,447 £156 £1,603 £23,692 14.8 yrs £8,374
8 kW 7750 kWh 5967 kWh 1782 kWh £1,654 £178 £1,832 £25,726 14.0 yrs £10,921

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
27.72p/kWh
Daily Fixed Charge
69.95p/day
Local Sunshine
969kWh/kW
A 1 kW system generates ~969 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: 65% • Flats: 16% • Bungalows: 19% Based on 5,191 properties

Coverage

Sefton (98%)|West Lancashire (2%)

Areas Covered

Harington, Ravenmeols, Rural West

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.