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

Solar Panels in PA80 (Na h-Eileanan Siar)

See if solar pays off for you in Na h-Eileanan Siar — 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
15.3 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£664
What you save every year
Profit Over 25 Years
£6,424
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 5.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 789 kWh per year on a south-facing roof. We value self-used electricity at 27.1p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
27.1p/kWh
Standing charge
61.0p/day
Sunshine yield (south)
789 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: £664, Upfront: £10,173, 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 1578 kWh 631 kWh 947 kWh £171 £95 £266 £4,069 15.3 yrs £1,242
3 kW 2368 kWh 947 kWh 1421 kWh £256 £142 £398 £6,104 15.3 yrs £1,863
4 kW 3157 kWh 1263 kWh 1894 kWh £342 £189 £531 £8,138 15.3 yrs £2,484
5 kW 3946 kWh 1578 kWh 2368 kWh £427 £237 £664 £10,173 15.3 yrs £3,104
6 kW 4735 kWh 1894 kWh 2841 kWh £513 £284 £797 £12,207 15.3 yrs £3,725
7 kW 5524 kWh 2210 kWh 3315 kWh £598 £331 £929 £14,242 15.3 yrs £4,346
8 kW 6313 kWh 2525 kWh 3788 kWh £683 £379 £1,062 £16,276 15.3 yrs £4,967

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: £798, Upfront: £12,273, Break-even: 15.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1578 kWh 947 kWh 631 kWh £256 £63 £319 £6,169 19.3 yrs £219
3 kW 2368 kWh 1421 kWh 947 kWh £384 £95 £479 £8,204 17.1 yrs £1,378
4 kW 3157 kWh 1894 kWh 1263 kWh £513 £126 £639 £10,238 16.0 yrs £2,538
5 kW 3946 kWh 2368 kWh 1578 kWh £641 £158 £798 £12,273 15.4 yrs £3,697
6 kW 4735 kWh 2841 kWh 1894 kWh £769 £189 £958 £14,307 14.9 yrs £4,857
7 kW 5524 kWh 3315 kWh 2210 kWh £897 £221 £1,118 £16,342 14.6 yrs £6,016
8 kW 6313 kWh 3788 kWh 2525 kWh £1,025 £253 £1,278 £18,376 14.4 yrs £7,175

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: £866, Upfront: £13,673, 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 1578 kWh 1105 kWh 474 kWh £299 £47 £346 £7,569 21.9 yrs £-643
3 kW 2368 kWh 1657 kWh 710 kWh £448 £71 £519 £9,604 18.5 yrs £786
4 kW 3157 kWh 2210 kWh 947 kWh £598 £95 £693 £11,638 16.8 yrs £2,215
5 kW 3946 kWh 2762 kWh 1184 kWh £747 £118 £866 £13,673 15.8 yrs £3,643
6 kW 4735 kWh 3315 kWh 1421 kWh £897 £142 £1,039 £15,707 15.1 yrs £5,072
7 kW 5524 kWh 3867 kWh 1657 kWh £1,046 £166 £1,212 £17,742 14.6 yrs £6,501
8 kW 6313 kWh 4419 kWh 1894 kWh £1,196 £189 £1,385 £19,776 14.3 yrs £7,929

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: £886, Upfront: £15,423, Break-even: 17.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1578 kWh 1152 kWh 426 kWh £312 £43 £354 £9,319 26.3 yrs £-2,231
3 kW 2368 kWh 1728 kWh 639 kWh £468 £64 £532 £11,354 21.4 yrs £-722
4 kW 3157 kWh 2304 kWh 852 kWh £624 £85 £709 £13,388 18.9 yrs £788
5 kW 3946 kWh 2880 kWh 1065 kWh £779 £107 £886 £15,423 17.4 yrs £2,297
6 kW 4735 kWh 3457 kWh 1278 kWh £935 £128 £1,063 £17,457 16.4 yrs £3,807
7 kW 5524 kWh 4033 kWh 1492 kWh £1,091 £149 £1,240 £19,492 15.7 yrs £5,316
8 kW 6313 kWh 4609 kWh 1705 kWh £1,247 £170 £1,418 £21,526 15.2 yrs £6,826

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: £899, Upfront: £17,173, Break-even: 19.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1578 kWh 1184 kWh 395 kWh £320 £39 £360 £11,069 30.8 yrs £-3,873
3 kW 2368 kWh 1776 kWh 592 kWh £480 £59 £540 £13,104 24.3 yrs £-2,310
4 kW 3157 kWh 2368 kWh 789 kWh £641 £79 £720 £15,138 21.0 yrs £-747
5 kW 3946 kWh 2959 kWh 986 kWh £801 £99 £899 £17,173 19.1 yrs £817
6 kW 4735 kWh 3551 kWh 1184 kWh £961 £118 £1,079 £19,207 17.8 yrs £2,380
7 kW 5524 kWh 4143 kWh 1381 kWh £1,121 £138 £1,259 £21,242 16.9 yrs £3,943
8 kW 6313 kWh 4735 kWh 1578 kWh £1,281 £158 £1,439 £23,276 16.2 yrs £5,507

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: £913, Upfront: £19,623, Break-even: 21.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1578 kWh 1215 kWh 363 kWh £329 £36 £365 £13,519 37.0 yrs £-6,216
3 kW 2368 kWh 1823 kWh 545 kWh £493 £54 £548 £15,554 28.4 yrs £-4,598
4 kW 3157 kWh 2431 kWh 726 kWh £658 £73 £730 £17,588 24.1 yrs £-2,981
5 kW 3946 kWh 3038 kWh 908 kWh £822 £91 £913 £19,623 21.5 yrs £-1,364
6 kW 4735 kWh 3646 kWh 1089 kWh £987 £109 £1,096 £21,657 19.8 yrs £253
7 kW 5524 kWh 4254 kWh 1271 kWh £1,151 £127 £1,278 £23,692 18.5 yrs £1,870
8 kW 6313 kWh 4861 kWh 1452 kWh £1,315 £145 £1,461 £25,726 17.6 yrs £3,487

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
27.06p/kWh
Daily Fixed Charge
61.00p/day
Local Sunshine
789kWh/kW
A 1 kW system generates ~789 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

No EPC data available for this outcode

Coverage

Na h-Eileanan Siar (58%)|Highland (42%)

Areas Covered

Barraigh agus Bhatarsaigh, Fort William and Ardnamurchan

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.