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

Solar Panels in HS6 (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
14.8 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£688
What you save every year
Profit Over 25 Years
£7,023
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 818 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)
818 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: £688, Upfront: £10,173, Break-even: 14.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1635 kWh 654 kWh 981 kWh £177 £98 £275 £4,069 14.8 yrs £1,434
3 kW 2453 kWh 981 kWh 1472 kWh £266 £147 £413 £6,104 14.8 yrs £2,150
4 kW 3271 kWh 1308 kWh 1962 kWh £354 £196 £550 £8,138 14.8 yrs £2,867
5 kW 4088 kWh 1635 kWh 2453 kWh £443 £245 £688 £10,173 14.8 yrs £3,584
6 kW 4906 kWh 1962 kWh 2944 kWh £531 £294 £825 £12,207 14.8 yrs £4,301
7 kW 5724 kWh 2289 kWh 3434 kWh £620 £343 £963 £14,242 14.8 yrs £5,017
8 kW 6541 kWh 2617 kWh 3925 kWh £708 £392 £1,101 £16,276 14.8 yrs £5,734

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: £827, Upfront: £12,273, Break-even: 14.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1635 kWh 981 kWh 654 kWh £266 £65 £331 £6,169 18.6 yrs £449
3 kW 2453 kWh 1472 kWh 981 kWh £398 £98 £496 £8,204 16.5 yrs £1,724
4 kW 3271 kWh 1962 kWh 1308 kWh £531 £131 £662 £10,238 15.5 yrs £2,999
5 kW 4088 kWh 2453 kWh 1635 kWh £664 £164 £827 £12,273 14.8 yrs £4,274
6 kW 4906 kWh 2944 kWh 1962 kWh £797 £196 £993 £14,307 14.4 yrs £5,548
7 kW 5724 kWh 3434 kWh 2289 kWh £929 £229 £1,158 £16,342 14.1 yrs £6,823
8 kW 6541 kWh 3925 kWh 2617 kWh £1,062 £262 £1,324 £18,376 13.9 yrs £8,098

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: £897, Upfront: £13,673, 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 1635 kWh 1145 kWh 491 kWh £310 £49 £359 £7,569 21.1 yrs £-393
3 kW 2453 kWh 1717 kWh 736 kWh £465 £74 £538 £9,604 17.8 yrs £1,161
4 kW 3271 kWh 2289 kWh 981 kWh £620 £98 £718 £11,638 16.2 yrs £2,715
5 kW 4088 kWh 2862 kWh 1226 kWh £774 £123 £897 £13,673 15.2 yrs £4,269
6 kW 4906 kWh 3434 kWh 1472 kWh £929 £147 £1,076 £15,707 14.6 yrs £5,822
7 kW 5724 kWh 4007 kWh 1717 kWh £1,084 £172 £1,256 £17,742 14.1 yrs £7,376
8 kW 6541 kWh 4579 kWh 1962 kWh £1,239 £196 £1,435 £19,776 13.8 yrs £8,930

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: £918, Upfront: £15,423, 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 1635 kWh 1194 kWh 442 kWh £323 £44 £367 £9,319 25.4 yrs £-1,975
3 kW 2453 kWh 1791 kWh 662 kWh £485 £66 £551 £11,354 20.6 yrs £-338
4 kW 3271 kWh 2388 kWh 883 kWh £646 £88 £734 £13,388 18.2 yrs £1,300
5 kW 4088 kWh 2984 kWh 1104 kWh £808 £110 £918 £15,423 16.8 yrs £2,937
6 kW 4906 kWh 3581 kWh 1325 kWh £969 £132 £1,102 £17,457 15.8 yrs £4,574
7 kW 5724 kWh 4178 kWh 1545 kWh £1,131 £155 £1,285 £19,492 15.2 yrs £6,212
8 kW 6541 kWh 4775 kWh 1766 kWh £1,292 £177 £1,469 £21,526 14.7 yrs £7,849

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: £932, Upfront: £17,173, Break-even: 18.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1635 kWh 1226 kWh 409 kWh £332 £41 £373 £11,069 29.7 yrs £-3,614
3 kW 2453 kWh 1840 kWh 613 kWh £498 £61 £559 £13,104 23.4 yrs £-1,920
4 kW 3271 kWh 2453 kWh 818 kWh £664 £82 £746 £15,138 20.3 yrs £-227
5 kW 4088 kWh 3066 kWh 1022 kWh £830 £102 £932 £17,173 18.4 yrs £1,466
6 kW 4906 kWh 3679 kWh 1226 kWh £996 £123 £1,118 £19,207 17.2 yrs £3,159
7 kW 5724 kWh 4293 kWh 1431 kWh £1,162 £143 £1,305 £21,242 16.3 yrs £4,852
8 kW 6541 kWh 4906 kWh 1635 kWh £1,328 £164 £1,491 £23,276 15.6 yrs £6,546

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: £946, Upfront: £19,623, Break-even: 20.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1635 kWh 1259 kWh 376 kWh £341 £38 £378 £13,519 35.7 yrs £-5,952
3 kW 2453 kWh 1889 kWh 564 kWh £511 £56 £568 £15,554 27.4 yrs £-4,203
4 kW 3271 kWh 2518 kWh 752 kWh £681 £75 £757 £17,588 23.2 yrs £-2,454
5 kW 4088 kWh 3148 kWh 940 kWh £852 £94 £946 £19,623 20.7 yrs £-705
6 kW 4906 kWh 3778 kWh 1128 kWh £1,022 £113 £1,135 £21,657 19.1 yrs £1,044
7 kW 5724 kWh 4407 kWh 1316 kWh £1,193 £132 £1,324 £23,692 17.9 yrs £2,793
8 kW 6541 kWh 5037 kWh 1504 kWh £1,363 £150 £1,513 £25,726 17.0 yrs £4,542

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
818kWh/kW
A 1 kW system generates ~818 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

Uibhist a Tuath

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.