Harlech sits on the Cardigan Bay coast inside Eryri (Snowdonia) National Park, with the thirteenth-century castle designated a UNESCO World Heritage Site. The LL46 postcode covers Harlech itself plus Llanfair and the coastal strip out to Llandanwg. For solar PV, the combination of a national park designation, a World Heritage buffer zone, and genuinely excellent coastal irradiance means the economics are strong but the planning path is more deliberate than an average Welsh site.
LL46 solar yield
PVGIS modelling for LL46 returns 935 to 960 kWh per kWp per annum for a south-facing rooftop at 30 to 35 degrees pitch. The coastal aspect helps summer yield, and the long hours of evening light in high summer extend the useful generation window. Expect a 4 kW domestic array to deliver 3,700 to 3,800 kWh in year one, and a 50 kWp commercial array around 46,500 to 48,000 kWh.
Planning inside Eryri and the World Heritage buffer
Eryri National Park Authority is the planning authority for LL46, not Gwynedd Council. The key considerations:
- National park designation — the permitted development thresholds for solar on dwellings and commercial buildings are tighter inside a national park. In practice, arrays on principal elevations visible from highways or public footpaths will usually require full planning permission.
- World Heritage buffer — properties within the setting of Harlech Castle face additional scrutiny on visual impact. The Castle sits on high ground and is visible from most of the town, so “out of sight of the castle” is the test that usually matters most.
- Listed buildings and conservation area — Harlech has both. Listed building consent is required for any external alteration to a listed property, and conservation area consent is required within the designated area.
What usually works:
- Rear-pitch or concealed-aspect arrays on dwellings not visible from the castle viewshed or public realm
- All-black modules which reduce visual contrast with slate
- Pitched-roof integration rather than above-roof frames where visual impact is a concern
- Barn-and-outbuilding arrays on agricultural properties in Llanfair and the coastal strip
What we typically recommend for Harlech
For domestic clients, the realistic entry point is a 4 to 5 kWp array on a rear or side pitch plus a 5 to 10 kWh battery. Payback on this configuration under current Welsh electricity pricing lands at 8 to 10 years, and the property value uplift in a National Park property is materially better than average because EPC ratings are disproportionately important in second-home and holiday-let markets.
For commercial clients, the main opportunities are in the smaller hospitality estate around the town and in the agricultural belt. Holiday lets in particular benefit because the summer demand profile correlates closely with the high-yield window.
Grid and MCS
LL46 sits in SP Energy Networks licence area (not NGED). G99 application timelines are broadly similar at 6 to 8 weeks for Type A. MCS certification is standard on every FLD install and is non-negotiable for insurance and for any future Smart Export Guarantee or battery arbitrage tariff eligibility.
Distance and logistics
Harlech is a three-hour drive from Swansea. For an installation of meaningful value, we mobilise a full crew on a Monday-to-Friday deployment with accommodation factored in. For smaller domestic installations we pair trips with other Eryri-area work where possible to keep mobilisation costs contained.
Starting the conversation
If you own a property in LL46 or a commercial rooftop in the Harlech area and want a realistic assessment including a frank view of the planning path, call Paul direct on 01792 321123.
