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

Solar Panels in LL54 (Gwynedd)

See if solar pays off for you in Gwynedd — 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
12.7 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£802
What you save every year
Profit Over 25 Years
£9,867
After paying itself off, you're this much ahead

Ready to Get Started?

Get your free quote from Blue Ape Renewables. They'll connect you with MCS-certified installers in your area and handle all the paperwork.

Get Solar Quote →
4.8★ Trustpilot • Octopus Energy trusted partner • MCS certified • No obligation
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 938 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)
938 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: £802, Upfront: £10,173, Break-even: 12.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1876 kWh 751 kWh 1126 kWh £208 £113 £321 £4,069 12.7 yrs £2,344
3 kW 2815 kWh 1126 kWh 1689 kWh £312 £169 £481 £6,104 12.7 yrs £3,515
4 kW 3753 kWh 1501 kWh 2252 kWh £416 £225 £641 £8,138 12.7 yrs £4,687
5 kW 4691 kWh 1876 kWh 2815 kWh £520 £281 £802 £10,173 12.7 yrs £5,859
6 kW 5629 kWh 2252 kWh 3377 kWh £624 £338 £962 £12,207 12.7 yrs £7,031
7 kW 6567 kWh 2627 kWh 3940 kWh £728 £394 £1,122 £14,242 12.7 yrs £8,202
8 kW 7505 kWh 3002 kWh 4503 kWh £832 £450 £1,283 £16,276 12.7 yrs £9,374

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: £968, Upfront: £12,273, Break-even: 12.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1876 kWh 1126 kWh 751 kWh £312 £75 £387 £6,169 15.9 yrs £1,574
3 kW 2815 kWh 1689 kWh 1126 kWh £468 £113 £581 £8,204 14.1 yrs £3,410
4 kW 3753 kWh 2252 kWh 1501 kWh £624 £150 £774 £10,238 13.2 yrs £5,247
5 kW 4691 kWh 2815 kWh 1876 kWh £780 £188 £968 £12,273 12.7 yrs £7,084
6 kW 5629 kWh 3377 kWh 2252 kWh £936 £225 £1,161 £14,307 12.3 yrs £8,921
7 kW 6567 kWh 3940 kWh 2627 kWh £1,092 £263 £1,355 £16,342 12.1 yrs £10,757
8 kW 7505 kWh 4503 kWh 3002 kWh £1,248 £300 £1,549 £18,376 11.9 yrs £12,594

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: £1,051, Upfront: £13,673, Break-even: 13.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1876 kWh 1313 kWh 563 kWh £364 £56 £420 £7,569 18.0 yrs £838
3 kW 2815 kWh 1970 kWh 844 kWh £546 £84 £631 £9,604 15.2 yrs £3,008
4 kW 3753 kWh 2627 kWh 1126 kWh £728 £113 £841 £11,638 13.8 yrs £5,177
5 kW 4691 kWh 3284 kWh 1407 kWh £910 £141 £1,051 £13,673 13.0 yrs £7,346
6 kW 5629 kWh 3940 kWh 1689 kWh £1,092 £169 £1,261 £15,707 12.5 yrs £9,515
7 kW 6567 kWh 4597 kWh 1970 kWh £1,274 £197 £1,471 £17,742 12.1 yrs £11,685
8 kW 7505 kWh 5254 kWh 2252 kWh £1,456 £225 £1,682 £19,776 11.8 yrs £13,854

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: £1,076, Upfront: £15,423, Break-even: 14.3 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1876 kWh 1370 kWh 507 kWh £380 £51 £430 £9,319 21.7 yrs £-712
3 kW 2815 kWh 2055 kWh 760 kWh £570 £76 £646 £11,354 17.6 yrs £1,557
4 kW 3753 kWh 2739 kWh 1013 kWh £759 £101 £861 £13,388 15.6 yrs £3,826
5 kW 4691 kWh 3424 kWh 1267 kWh £949 £127 £1,076 £15,423 14.3 yrs £6,095
6 kW 5629 kWh 4109 kWh 1520 kWh £1,139 £152 £1,291 £17,457 13.5 yrs £8,364
7 kW 6567 kWh 4794 kWh 1773 kWh £1,329 £177 £1,506 £19,492 12.9 yrs £10,633
8 kW 7505 kWh 5479 kWh 2026 kWh £1,519 £203 £1,721 £21,526 12.5 yrs £12,902

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: £1,092, Upfront: £17,173, Break-even: 15.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1876 kWh 1407 kWh 469 kWh £390 £47 £437 £11,069 25.3 yrs £-2,329
3 kW 2815 kWh 2111 kWh 704 kWh £585 £70 £655 £13,104 20.0 yrs £6
4 kW 3753 kWh 2815 kWh 938 kWh £780 £94 £874 £15,138 17.3 yrs £2,342
5 kW 4691 kWh 3518 kWh 1173 kWh £975 £117 £1,092 £17,173 15.7 yrs £4,677
6 kW 5629 kWh 4222 kWh 1407 kWh £1,170 £141 £1,311 £19,207 14.7 yrs £7,013
7 kW 6567 kWh 4925 kWh 1642 kWh £1,365 £164 £1,529 £21,242 13.9 yrs £9,348
8 kW 7505 kWh 5629 kWh 1876 kWh £1,560 £188 £1,748 £23,276 13.3 yrs £11,684

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: £1,109, Upfront: £19,623, Break-even: 17.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1876 kWh 1445 kWh 432 kWh £400 £43 £444 £13,519 30.5 yrs £-4,646
3 kW 2815 kWh 2167 kWh 647 kWh £601 £65 £665 £15,554 23.4 yrs £-2,244
4 kW 3753 kWh 2890 kWh 863 kWh £801 £86 £887 £17,588 19.8 yrs £158
5 kW 4691 kWh 3612 kWh 1079 kWh £1,001 £108 £1,109 £19,623 17.7 yrs £2,560
6 kW 5629 kWh 4334 kWh 1295 kWh £1,201 £129 £1,331 £21,657 16.3 yrs £4,962
7 kW 6567 kWh 5057 kWh 1510 kWh £1,402 £151 £1,553 £23,692 15.3 yrs £7,364
8 kW 7505 kWh 5779 kWh 1726 kWh £1,602 £173 £1,775 £25,726 14.5 yrs £9,766

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
938kWh/kW
A 1 kW system generates ~938 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: 76% • Flats: 3% • Bungalows: 20% Based on 2,801 properties

Coverage

Gwynedd (100%)

Areas Covered

Y Groeslon, Tryfan, Llanllyfni, Clynnog, Pen-y-groes, Llanwnda, Yr Eifl, Waunfawr + 4 more

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.