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

Solar Panels in PA85 (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
16.8 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£604
What you save every year
Profit Over 25 Years
£4,938
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 719 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)
719 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: £604, Upfront: £10,173, Break-even: 16.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1437 kWh 575 kWh 862 kWh £156 £86 £242 £4,069 16.8 yrs £766
3 kW 2156 kWh 862 kWh 1293 kWh £233 £129 £363 £6,104 16.8 yrs £1,149
4 kW 2874 kWh 1150 kWh 1724 kWh £311 £172 £484 £8,138 16.8 yrs £1,533
5 kW 3593 kWh 1437 kWh 2156 kWh £389 £216 £604 £10,173 16.8 yrs £1,916
6 kW 4311 kWh 1724 kWh 2587 kWh £467 £259 £725 £12,207 16.8 yrs £2,299
7 kW 5030 kWh 2012 kWh 3018 kWh £544 £302 £846 £14,242 16.8 yrs £2,682
8 kW 5748 kWh 2299 kWh 3449 kWh £622 £345 £967 £16,276 16.8 yrs £3,065

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: £727, Upfront: £12,273, Break-even: 16.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1437 kWh 862 kWh 575 kWh £233 £57 £291 £6,169 21.2 yrs £-353
3 kW 2156 kWh 1293 kWh 862 kWh £350 £86 £436 £8,204 18.8 yrs £520
4 kW 2874 kWh 1724 kWh 1150 kWh £467 £115 £582 £10,238 17.6 yrs £1,394
5 kW 3593 kWh 2156 kWh 1437 kWh £583 £144 £727 £12,273 16.9 yrs £2,267
6 kW 4311 kWh 2587 kWh 1724 kWh £700 £172 £872 £14,307 16.4 yrs £3,141
7 kW 5030 kWh 3018 kWh 2012 kWh £817 £201 £1,018 £16,342 16.1 yrs £4,014
8 kW 5748 kWh 3449 kWh 2299 kWh £933 £230 £1,163 £18,376 15.8 yrs £4,888

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: £788, Upfront: £13,673, Break-even: 17.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1437 kWh 1006 kWh 431 kWh £272 £43 £315 £7,569 24.0 yrs £-1,263
3 kW 2156 kWh 1509 kWh 647 kWh £408 £65 £473 £9,604 20.3 yrs £-144
4 kW 2874 kWh 2012 kWh 862 kWh £544 £86 £631 £11,638 18.5 yrs £974
5 kW 3593 kWh 2515 kWh 1078 kWh £681 £108 £788 £13,673 17.3 yrs £2,093
6 kW 4311 kWh 3018 kWh 1293 kWh £817 £129 £946 £15,707 16.6 yrs £3,212
7 kW 5030 kWh 3521 kWh 1509 kWh £953 £151 £1,104 £17,742 16.1 yrs £4,330
8 kW 5748 kWh 4024 kWh 1724 kWh £1,089 £172 £1,261 £19,776 15.7 yrs £5,449

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: £807, Upfront: £15,423, 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 1437 kWh 1049 kWh 388 kWh £284 £39 £323 £9,319 28.9 yrs £-2,866
3 kW 2156 kWh 1574 kWh 582 kWh £426 £58 £484 £11,354 23.5 yrs £-1,674
4 kW 2874 kWh 2098 kWh 776 kWh £568 £78 £645 £13,388 20.7 yrs £-481
5 kW 3593 kWh 2623 kWh 970 kWh £710 £97 £807 £15,423 19.1 yrs £711
6 kW 4311 kWh 3147 kWh 1164 kWh £852 £116 £968 £17,457 18.0 yrs £1,903
7 kW 5030 kWh 3672 kWh 1358 kWh £994 £136 £1,129 £19,492 17.3 yrs £3,095
8 kW 5748 kWh 4196 kWh 1552 kWh £1,135 £155 £1,291 £21,526 16.7 yrs £4,287

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: £819, Upfront: £17,173, Break-even: 21.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1437 kWh 1078 kWh 359 kWh £292 £36 £328 £11,069 33.8 yrs £-4,518
3 kW 2156 kWh 1617 kWh 539 kWh £437 £54 £491 £13,104 26.7 yrs £-3,276
4 kW 2874 kWh 2156 kWh 719 kWh £583 £72 £655 £15,138 23.1 yrs £-2,035
5 kW 3593 kWh 2694 kWh 898 kWh £729 £90 £819 £17,173 21.0 yrs £-794
6 kW 4311 kWh 3233 kWh 1078 kWh £875 £108 £983 £19,207 19.5 yrs £447
7 kW 5030 kWh 3772 kWh 1257 kWh £1,021 £126 £1,146 £21,242 18.5 yrs £1,688
8 kW 5748 kWh 4311 kWh 1437 kWh £1,167 £144 £1,310 £23,276 17.8 yrs £2,929

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: £831, Upfront: £19,623, Break-even: 23.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1437 kWh 1107 kWh 331 kWh £299 £33 £332 £13,519 40.7 yrs £-6,870
3 kW 2156 kWh 1660 kWh 496 kWh £449 £50 £499 £15,554 31.2 yrs £-5,579
4 kW 2874 kWh 2213 kWh 661 kWh £599 £66 £665 £17,588 26.5 yrs £-4,289
5 kW 3593 kWh 2766 kWh 826 kWh £749 £83 £831 £19,623 23.6 yrs £-2,999
6 kW 4311 kWh 3320 kWh 992 kWh £898 £99 £997 £21,657 21.7 yrs £-1,709
7 kW 5030 kWh 3873 kWh 1157 kWh £1,048 £116 £1,164 £23,692 20.4 yrs £-419
8 kW 5748 kWh 4426 kWh 1322 kWh £1,198 £132 £1,330 £25,726 19.3 yrs £872

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
719kWh/kW
A 1 kW system generates ~719 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 (100%)

Areas Covered

Na Hearadh

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.