Solar panel cost in Gwynedd (LL57)

See realistic solar installation costs, savings and payback for LL57 (Gwynedd) in under a minute using official UK data. Start with the calculator, then get a no-obligation quote from an MCS-certified installer. You can also ask the SolarByPostcode assistant to sanity-check your roof, bills and plans.

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
12.1 years
After this, it's pure profit
Upfront Cost
£8,139
What you pay to get started
Annual Benefit
£675
What you save every year
Profit Over 25 Years
£8,746
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: The official cost per kW is lower above 4 kW, so a 5–6 kW system can pay back a little faster than a 3–4 kW system on otherwise identical assumptions.
  • 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

Panel costs: Uses March 2026 TIC mean installation costs: £1,827/kW up to 4 kW and £1,628/kW above 4 kW.

Other costs: Battery prices are modelled at £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 792 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
70.8p/day
Sunshine yield (south)
792 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: £675, Upfront: £8,139, Break-even: 12.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1583 kWh 633 kWh 950 kWh £175 £95 £270 £3,256 12.1 yrs £2,148
3 kW 2375 kWh 950 kWh 1425 kWh £263 £142 £405 £4,883 12.1 yrs £3,222
4 kW 3166 kWh 1267 kWh 1900 kWh £350 £190 £540 £6,511 12.1 yrs £4,296
5 kW 3958 kWh 1583 kWh 2375 kWh £438 £237 £675 £8,139 12.1 yrs £5,369
6 kW 4750 kWh 1900 kWh 2850 kWh £526 £285 £810 £9,767 12.1 yrs £6,443
7 kW 5541 kWh 2217 kWh 3325 kWh £613 £332 £946 £11,394 12.1 yrs £7,517
8 kW 6333 kWh 2533 kWh 3800 kWh £701 £380 £1,081 £13,022 12.1 yrs £8,591

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

3 kWh battery 5 kW example → Annual benefit: £815, Upfront: £10,239, 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 1583 kWh 950 kWh 633 kWh £263 £63 £326 £5,356 16.4 yrs £1,166
3 kW 2375 kWh 1425 kWh 950 kWh £394 £95 £489 £6,983 14.3 yrs £2,799
4 kW 3166 kWh 1900 kWh 1267 kWh £526 £127 £652 £8,611 13.2 yrs £4,432
5 kW 3958 kWh 2375 kWh 1583 kWh £657 £158 £815 £10,239 12.6 yrs £6,065
6 kW 4750 kWh 2850 kWh 1900 kWh £788 £190 £978 £11,867 12.1 yrs £7,698
7 kW 5541 kWh 3325 kWh 2217 kWh £920 £222 £1,141 £13,494 11.8 yrs £9,332
8 kW 6333 kWh 3800 kWh 2533 kWh £1,051 £253 £1,304 £15,122 11.6 yrs £10,965

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

5 kWh battery 5 kW example → Annual benefit: £885, Upfront: £11,639, Break-even: 13.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1583 kWh 1108 kWh 475 kWh £307 £47 £354 £6,756 19.1 yrs £325
3 kW 2375 kWh 1662 kWh 712 kWh £460 £71 £531 £8,383 15.8 yrs £2,238
4 kW 3166 kWh 2217 kWh 950 kWh £613 £95 £708 £10,011 14.1 yrs £4,151
5 kW 3958 kWh 2771 kWh 1187 kWh £766 £119 £885 £11,639 13.1 yrs £6,063
6 kW 4750 kWh 3325 kWh 1425 kWh £920 £142 £1,062 £13,267 12.5 yrs £7,976
7 kW 5541 kWh 3879 kWh 1662 kWh £1,073 £166 £1,239 £14,894 12.0 yrs £9,889
8 kW 6333 kWh 4433 kWh 1900 kWh £1,226 £190 £1,416 £16,522 11.7 yrs £11,801

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

7.5 kWh battery 5 kW example → Annual benefit: £906, Upfront: £13,389, 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 1583 kWh 1156 kWh 427 kWh £320 £43 £362 £8,506 23.5 yrs £-1,257
3 kW 2375 kWh 1734 kWh 641 kWh £480 £64 £544 £10,133 18.6 yrs £740
4 kW 3166 kWh 2312 kWh 855 kWh £639 £85 £725 £11,761 16.2 yrs £2,736
5 kW 3958 kWh 2889 kWh 1069 kWh £799 £107 £906 £13,389 14.8 yrs £4,733
6 kW 4750 kWh 3467 kWh 1282 kWh £959 £128 £1,087 £15,017 13.8 yrs £6,729
7 kW 5541 kWh 4045 kWh 1496 kWh £1,119 £150 £1,269 £16,644 13.1 yrs £8,726
8 kW 6333 kWh 4623 kWh 1710 kWh £1,279 £171 £1,450 £18,272 12.6 yrs £10,722

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

10 kWh battery 5 kW example → Annual benefit: £920, Upfront: £15,139, Break-even: 16.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1583 kWh 1187 kWh 396 kWh £328 £40 £368 £10,256 27.9 yrs £-2,895
3 kW 2375 kWh 1781 kWh 594 kWh £493 £59 £552 £11,883 21.5 yrs £-843
4 kW 3166 kWh 2375 kWh 792 kWh £657 £79 £736 £13,511 18.4 yrs £1,210
5 kW 3958 kWh 2969 kWh 990 kWh £821 £99 £920 £15,139 16.5 yrs £3,262
6 kW 4750 kWh 3562 kWh 1187 kWh £985 £119 £1,104 £16,767 15.2 yrs £5,315
7 kW 5541 kWh 4156 kWh 1385 kWh £1,150 £139 £1,288 £18,394 14.3 yrs £7,367
8 kW 6333 kWh 4750 kWh 1583 kWh £1,314 £158 £1,472 £20,022 13.6 yrs £9,420

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, battery £/kWh = 700.

13.5 kWh battery 5 kW example → Annual benefit: £934, Upfront: £17,589, Break-even: 18.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1583 kWh 1219 kWh 364 kWh £337 £36 £374 £12,706 34.0 yrs £-5,233
3 kW 2375 kWh 1829 kWh 546 kWh £506 £55 £560 £14,333 25.6 yrs £-3,125
4 kW 3166 kWh 2438 kWh 728 kWh £674 £73 £747 £15,961 21.4 yrs £-1,016
5 kW 3958 kWh 3048 kWh 910 kWh £843 £91 £934 £17,589 18.8 yrs £1,092
6 kW 4750 kWh 3657 kWh 1092 kWh £1,012 £109 £1,121 £19,217 17.1 yrs £3,200
7 kW 5541 kWh 4267 kWh 1275 kWh £1,180 £127 £1,308 £20,844 15.9 yrs £5,309
8 kW 6333 kWh 4876 kWh 1457 kWh £1,349 £146 £1,494 £22,472 15.0 yrs £7,417

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 1,628, 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.

Before you request quotes in Gwynedd

Use the numbers above to sanity-check installer quotes. The main things to compare are system size, battery assumptions, payback claims, MCS certification, DNO paperwork and export assumptions.

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Seasonal solar output in LL57

Monthly generation per kilowatt of solar panels

kWh 23 Jan 39 Feb 70 Mar 98 Apr 109 May 107 Jun 100 Jul 87 Aug 69 Sep 47 Oct 26 Nov 18 Dec
Best month Worst month Winter (Dec–Feb) Other months

Winter output: 40.2% of an average month (Dec–Feb)

Best / worst month: May / Dec

These figures show output per kilowatt (kW) of panels installed. In winter, a 1 kW system here produces about 27 kWh per month; the average month produces around 66 kWh. So a typical 4 kW home system would generate roughly 106 kWh in winter, or 264 kWh in an average month.

Your Area at a Glance

Your Electricity Rate
27.66p/kWh
Daily Fixed Charge
70.76p/day
Local Sunshine
792kWh/kW
A 1 kW system generates ~792 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

Houses: 68% • Flats: 23% • Bungalows: 8% Based on 7,061 properties

Coverage

Gwynedd (100%)

Areas Covered

Canol Bangor, Dwyrain Bangor, Tre-garth a Mynydd Llandygái, Y Faenol, Arllechwedd, Gerlan, Rachub, Canol Bethesda + 4 more

Data Sources & Assumptions

Solar yield: PVGIS (EU Joint Research Centre), January 2025 data

Electricity rates: Ofgem price cap, Q3 2026

Installation costs: DESNZ/MCS data, March 2026 (TIC)

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.