Solar panel guide for Wales

While a solar project in Wales asks the same technical questions as one anywhere in the UK, it also brings Welsh planning, building and support routes. This guide walks through the steps in order. It runs from your roof to your paperwork.

Since Solar Cymru is an independent guide, we are not an installer, lender or government service. We point you to official sources throughout. You can also ask for quotes from MCS-certified installers when you are ready.

Start with the property

Because every roof differs, begin with yours. An installer assesses the usable roof area, orientation, slope, shading, condition and structure. They also check where your meter and consumer unit sit, and where cables and equipment can go.

The Energy Saving Trust describes a typical home system as about 4.5 kWp. That uses around 12 panels and covers roughly 20 to 30 square metres of roof. Our post on how many solar panels you need shows how to size a system for your home.

Direction matters, yet less than people expect. A south-facing roof at 35 degrees makes about 820 to 1,060 kWh a year for each kWp across Wales. East or west faces make about 15 to 20% less. Our solar yield guide gives place-by-place figures. Our post on solar panels in Welsh weather tackles the rain question.

Shade deserves a careful look too. Trees, chimneys and neighbouring buildings can all cast shadows. The MCS performance estimate must state a shade factor. Power optimisers or microinverters can limit the loss when part of the array is shaded, yet they add nothing on an unshaded roof.

Check the Welsh planning rules

Fixing solar panels to the roof of a house in Wales is in many cases permitted development. Planning permission is therefore often not needed, but the rules have exceptions. Panels must not stick out more than 200 mm from the roof slope. They must not stand higher than the highest part of the roof, not counting a chimney.

Flat roofs are inside the rules, although they have their own limits. Panels must sit at least 1 m from the edge and rise no more than 1 m. Listed buildings work differently, because permitted development does not apply. You need planning permission and are likely to need listed building consent.

However, in a conservation area, panels on a wall that faces a highway need planning permission. A council can also remove these rights through an Article 4 direction or a planning condition. Check the council’s planning register, and read our planning permission guide for the full picture.

Building Regulations and the electrical work

Building Regulations normally apply when solar goes on a roof. Because the panels add weight, the installer must check and prove that the roof can carry the load. Some roofs need strengthening, and the electrical work falls under the rules too.

Meanwhile, an installer in a competent person scheme can certify the work and notify the council. Ask which scheme yours belongs to, and ask for the compliance certificate at handover.

What it costs and what you save

Government data on 2025-26 installs shows about £1,400 to £1,950 per kilowatt for small systems across Great Britain, before any battery. For example, a typical 4.5 kWp home costs roughly £6,500 to £8,800. VAT on home solar is 0% until 31 March 2027, and then it is due to rise to 5%.

Since savings depend on how much power you use yourself, typical savings run around £450 to £500 or more a year. The Energy Saving Trust puts payback in mid Wales at around 9 to 10 years. Our post on how much solar panels cost in Wales goes into more detail. Our page on solar panel installation in Wales explains what a quote covers.

Grid connection, export and funding

Specifically, small systems up to 16 amps per phase follow the G98 route, which means 3.68 kW on a single-phase supply. The installer tells your network operator within 28 days of commissioning. Larger systems need the operator’s agreement first. Our grid and export guide explains the process.

Suppliers set Smart Export Guarantee rates. Ofgem’s 2024-25 report found an average near 4.4p per kWh on untied tariffs. Using your own power is worth more than exporting it, so compare tariffs before you sign.

There is no dedicated UK Government solar grant. In Wales, however, Warm Homes Nest can include solar for eligible low-income homes, and Green Homes Wales offers owner-occupier loans. See our solar funding guide for the rules.

Build an evidence trail

Specifically, keep your survey, design, performance estimate and permissions together. Add the network correspondence, contracts, certificates, warranties and commissioning documents. The MCS standard requires a written performance estimate and handover documents.

Good records matter for a long time, since panels should last 25 years or more. Our post on how long solar panels last explains warranties and inverter life. Our guide to choosing an installer lists what to ask before you sign.

Next steps

Therefore, start with your roof and your bills, then read the pages above that fit your situation. When you are ready, use our get quotes page to send an enquiry to MCS-certified installers. The step is opt-in.

Local detail can differ. For example, see our pages for solar installers in Cardiff and solar panels around Wrexham.