The short answer for Cardiff: a 4kW south-facing system in Cardiff generates about 4,170 kWh a year on the EU's PVGIS model — about 2% more than London. Installed prices for that size run roughly £6,600–£7,800 on the UK government's 2025/26 cost data, and at October–December 2026 South Wales electricity prices (26.55p/kWh) it is worth roughly £700 a year without a battery, or £900 if a battery lets you use most of it yourself.
Cardiff is split almost evenly between terraces and semis, and it has twice the Welsh share of flats. Most house enquiries here are for a 3–4kW system on a Victorian terrace or a suburban semi. Planning works to Welsh rules, not English ones, and Wales has its own interest-free loan for solar.
How much a solar panel system generates in Cardiff
The table uses the European Commission's PVGIS tool for Cardiff: crystalline panels at a 35° pitch, with PVGIS's standard 14% allowance for system losses and the local horizon. Your installer's MCS estimate will differ a little because MCS uses its own irradiance tables and your actual pitch and shading, but the gap between places and orientations is what matters here.
| Roof faces | Per kW | 3kW system | 4kW system | 6kW system |
|---|---|---|---|---|
| South | 1,042 kWh | 3,130 kWh | 4,170 kWh | 6,250 kWh |
| East | 809 kWh | 2,430 kWh | 3,240 kWh | 4,850 kWh |
| West | 834 kWh | 2,500 kWh | 3,340 kWh | 5,000 kWh |
Annual output, PVGIS 5.3 (SARAH3 satellite data, 2005–2023) for Cardiff, fetched 30 October 2026. Actual output varies year to year.
Of the 25 areas we cover, Cardiff ranks sixth for south-facing yield (Dorset is highest at 1,126 kWh per kW, Glasgow lowest at 853). The seasons matter as much as the location: in December a 4kW system here makes about 129 kWh for the whole month, against 524 kWh in June — which is why a battery is mostly a summer and shoulder-season tool, and why nobody should promise you winter bills near zero.
Cardiff's wet reputation doesn't carry over to solar. Output follows sunshine and sun angle, not rainfall, which is why the coastal city holds its own against London on the figures above. East- and west-facing roofs make about four-fifths of a south-facing one, so if your terrace in Roath, Canton, Splott or Grangetown has its slopes facing east and west rather than south, it's still worth quoting. Splitting panels across both slopes, with optimisers or two inverter inputs, is normal and spreads generation across the day.
What solar costs and saves in Cardiff
There is no separate "Cardiff price" for solar — installers price by system size, roof and access — so the fairest benchmark is the government's own cost series. Across domestic installations registered with MCS between April 2025 and March 2026, the average installed cost was £1,955 per kW for systems up to 4kW and £1,645 per kW for 4–10kW, VAT included and batteries excluded.
| System | Output in Cardiff | Typical installed price | Year-one value, no battery | Simple payback |
|---|---|---|---|---|
| 3kW | 3,130 kWh | £4,900–£5,900 | £600 | 9–11 years |
| 4kW | 4,170 kWh | £6,600–£7,800 | £700 | 9–11 years |
| 6kW | 6,250 kWh | £9,900–£11,700 | £1,100 | 9–11 years |
Price range: DESNZ Solar PV cost data (published 28 May 2026), each size priced between the 4–10kW average (£1,645/kW) and the up-to-4kW average (£1,955/kW); bigger systems tend towards the lower figure per kW. Value: south-facing PVGIS output, 40% used in the home at the South Wales price-cap unit rate of 26.55p/kWh (1 October to 31 December 2026), the rest exported at 12p/kWh (the 12p rate several large suppliers pay their own import customers in September 2026). Payback ignores panel degradation, future price changes and inverter replacement.
Two things move those numbers more than anything about Cardiff itself. First, how much you use yourself: every unit you use saves 26.55p, every unit you export earns only what your export tariff pays — 12p in this illustration. Our illustration assumes you use 40% without a battery; with a battery taking that to around 70%, the same 4kW system is worth about £900 a year — but the battery adds several thousand pounds, so price it as its own line and judge it on its own payback (battery storage guide). Second, the export tariff: rates are set by suppliers, not Ofgem, and range widely — see the solar payback guide for current examples.
VAT on solar panels and batteries installed in homes is 0% until 31 March 2027 (how the relief works), so a quote that adds 20% VAT to a domestic install is wrong.
Ways to pay for solar in Cardiff
Group-buying: Cardiff Council led the first round of Switch Together (formerly Solar Together) for south-east Wales, with Cardiff Capital Region and iChoosr. In that round 156 Cardiff households had panels fitted (Cardiff Council). Round two's registration, first due to close on 27 March 2026, was reopened and finally closed on 5 June 2026 (Rent Smart Wales, Cardiff Council). You can register for future rounds on the Switch Together website. If a further round opens, its price is a useful benchmark for any quote.
Interest-free loan: Green Homes Wales, a Welsh Government scheme run by the Development Bank of Wales, lends £1,000 to £25,000 interest-free over up to 10 years. It covers solar panels, with or without a battery. It isn't means-tested, but it has credit and affordability checks, and it's for owners living in the home. Listed homes and landlords can't apply for now. You register interest with the bank, which issues application forms as funding allows (Development Bank of Wales). Apply through the bank, not through us.
Warm Homes loan: the UK government's Warm Homes Loan Scheme, published on GOV.UK on 28 October 2026, covers homes anywhere in the UK, including Wales. You apply to one of the listed lenders, directly or through an MCS installer arranging finance. GOV.UK says you can't use it and other government funding for the same improvement (GOV.UK).
Free routes: the Welsh Government's Nest scheme can fit free improvements, including solar panels, for owners and private renters on means-tested benefits or a low income in a poorly rated home (eligibility). Nest uses its own contractors, so it isn't something we can arrange.
Cardiff homes and what they mean for your roof
Census 2021 counted 147,333 households in Cardiff: 29.7% semi-detached, 29.6% terraced, 14.1% detached and 26.5% flats or maisonettes, with 58.0% owner-occupied and 24.3% privately rented (Wales: 66.1% owned).
On a Victorian or Edwardian terrace, the main rear slope is usually the best roof. It typically takes 8–10 panels, so expect quotes around 3–4kW. Many of these houses have a rear extension with its own small roof, often shaded by next door's for part of the day. Ask the surveyor for the shading assessment before you count it as extra output. Slate is common on older roofs, so check the quote names the fixing method for slate rather than tile hooks. On a semi with a hipped roof, the sloping end cuts the space on the main slope, so the rear slope or a second slope may be needed to reach 4kW.
A quarter of Cardiff homes are flats, more than twice the Welsh average. Because the Welsh permitted development rights for solar cover houses only (see the planning section), panels on a block start with the freeholder's agreement and a check with the council. Private renters, including students in shared houses, need the landlord to commission the work. Where bills are included in the rent, the landlord pays for the electricity and keeps the saving.
Planning permission in Cardiff
Planning is devolved, so Welsh rules apply here, not England's. For houses in Wales, solar panels on the roof are permitted development (no planning application) as long as they stand no more than 20cm proud of the roof slope and don't rise above the highest part of the roof, chimneys aside. On a flat roof they must sit at least 1 metre in from the edge and no more than 1 metre above it. The main exceptions are listed buildings, where the Welsh Government says you need planning permission and probably listed building consent; panels on a wall that forms the front or side of the house and faces a road in a conservation area or World Heritage Site; and homes where the council has removed permitted development rights with an Article 4 direction or a planning condition. The Welsh rights now cover houses only, not flats: for a flat or a block, ask the council's planning team first, and a shared roof also needs the freeholder's consent. The size limits for solar date from 2012. The changes in force from 1 June 2026 relaxed the rules for heat pumps, but they also redefined "dwellinghouse" for these rights so that it no longer includes a building containing flats, so blocks of flats lost the solar right they had had since 2012.
Cardiff Council lists 27 conservation areas, including Cathedral Road, Roath Park, Llandaff, Rhiwbina Garden Village, Church Road in Whitchurch and St Fagans (council page). The council says "many areas also have Article 4 Directions, which give additional controls over various minor alterations, such as alterations to windows". Solar isn't named, so if your house is in a conservation area, read that area's leaflet on the council page or send a pre-application enquiry before you commit. Cardiff has around 1,000 listed buildings, and Listed Building Consent is needed when work affects the character of a listed building or one in its grounds.
Connecting to the grid: National Grid Electricity Distribution (South Wales)
Cardiff's local electricity network is run by National Grid Electricity Distribution, which covers the South Wales licence area. It's the company your installer notifies or applies to for the grid connection. You don't need to contact it yourself, and your electricity supplier is a separate company.
For a typical home system the installer handles this. A single-phase installation up to 3.68kW of inverter capacity (16 amps per phase) is connected under the G98 process and the network operator is notified within 28 days of commissioning. Anything larger — including a bigger system, or panels plus a battery whose combined inverter capacity passes that limit — goes through G99, which needs the network operator's approval before installation and can add weeks. Ask your installer which route your design needs and whether an export limit is being applied.
Getting a quote in Cardiff
Tell us about your home
Postcode, property type and how you'd pay. Two minutes.
We pass it to one installer
If an accredited (MCS-certified) installer covers your area, we'll pass your enquiry to them, and only them. They can arrange a roof survey and quote.
Judge the quote
Check it against the figures on this page. If it's out of range, you can say no. No obligation at any stage.
How your enquiry is handled
- One installer introduction, fulfilling your request. If an accredited (MCS-certified) installer covers your area, we'll pass your enquiry to them, and only them — not a list of companies.
- No obligation, at any stage. You can say no at any point, including after the survey or the quote, and owe nothing.
- It costs you nothing. An installer may pay Great British Energy a referral fee if you go ahead, and that fee does not change your price.
- We are an independent guide, not an installer. Great British Energy Guide doesn't install anything and isn't the government body of a similar name. Your consent is recorded with the enquiry, as set out in our privacy policy.
Get your solar quote in Cardiff
One MCS-certified installer who covers your postcode. Nothing is shared until you submit.
What the quote should show
- The installer's MCS certificate number — needed for a Smart Export Guarantee tariff — and their consumer code (RECC or HIES).
- Named panel and inverter make and model, with quantities, and the MCS performance estimate for your roof in kWh a year. Every saving quoted to you should come from that estimate.
- Scaffolding stated as included or excluded, and any battery priced as a separate line.
- No VAT added on a home installation (0% until 31 March 2027), warranty terms split out, and, if financed, the total repayable next to the cash price.
The full checklist is on the solar quotes page.
Questions from Cardiff homeowners
Do I need planning permission for solar panels in Cardiff?
Usually not for a house. Under the Welsh rules, roof panels are permitted development if they stand no more than 20cm proud and stay below the ridge. Check first if the house is listed, or is in one of Cardiff's 27 conservation areas, many of which have Article 4 directions. Flats aren't covered by the rules, so ask the council.
Is Cardiff sunny enough for solar panels?
Yes. On PVGIS data a south-facing roof in Cardiff produces slightly more per kW than the same roof in London. East- and west-facing roofs make about four-fifths of that. Savings depend far more on how much of the output you use yourself than on the weather.
Can I get an interest-free loan for solar panels in Wales?
Green Homes Wales, run by the Development Bank of Wales for the Welsh Government, offers interest-free loans of £1,000 to £25,000 for owner-occupiers, including for solar panels with or without a battery. It has credit and affordability checks and isn't open to landlords or listed homes. You apply through the bank.
Are there free solar panels in Cardiff?
Only for some households. The Welsh Government's Nest scheme can fund solar panels for owners and private renters on means-tested benefits or a low income whose homes have a poor energy rating. This page is for people paying or financing. For funded routes, see the Cardiff energy grants page.
Can I put solar panels on a flat in Cardiff?
It's harder than for a house. Welsh permitted development rights for solar cover houses only, so a flat or block normally needs the freeholder's agreement and advice from the council's planning team, and often a planning application.
Other areas
- Solar in Birmingham
- Solar in Newcastle
- Solar in Manchester
- Solar in Bristol
- Solar in Sheffield
- Solar in Doncaster
- Solar in Nottingham
- Solar in Cornwall
- Solar in Aberdeen
- Solar in Cambridge
- Solar in Derby
- Solar in Devon
- Solar in Dorset
- Solar in Edinburgh
- Solar in Essex
- Solar in Glasgow
- Solar in Hull
- Solar in Kent
- Solar in Leeds
- Solar in Leicester
- Solar in Liverpool
- Solar in London
- Solar in Norfolk
- Solar in Telford & Shropshire
Heat pump pages: Birmingham, Bristol, Newcastle, Nottingham, Sheffield, Doncaster, Norfolk, Suffolk, West Wales, and all heat pump quotes.
Solar or heating for business premises in Wales? See Welsh business energy grants and loans and commercial solar panels.
Sources
- European Commission JRC, PVGIS 5.3 — grid-connected PV, Cardiff, 1kWp crystalline silicon, 35° slope, 14% system loss, south/east/west, SARAH3 2005–2023; queried 30 October 2026.
- Office for National Statistics, Census 2021 tables TS044 (accommodation type), TS046 (central heating), TS050 (bedrooms) and TS054 (tenure), local authority level, via Nomis.
- DESNZ, Solar PV cost data, updated 28 May 2026 — domestic, mean cost per kW, Total Installed Capacity basis, 2025/26 (Official Statistics in development).
- Ofgem, Changes to energy price cap between 1 October and 31 December 2026 (26 August 2026) and regional unit rates and standing charges; electricity at 0% VAT from 1 October 2026 to 31 March 2027 (HMRC).
- Ofgem, Smart Export Guarantee: tariffs must be above zero; suppliers with 150,000+ domestic customers must offer one. Supplier export rates checked on supplier websites, 23 September 2026.
- HMRC, VAT Notice 708/6: 0% on installing energy-saving materials in homes, 1 May 2023 to 31 March 2027.
- Town and Country Planning (General Permitted Development) Order 1995, Schedule 2 Part 40 Class A, as it applies in Wales (substituted by SI 2012/1346 (W. 167)); the General Permitted Development (Amendment) (Wales) Order 2026, article 6(a) (in force 1 June 2026), replaced the Part 40 definition of "dwellinghouse", which had included a building consisting wholly of flats, so that it excludes buildings containing flats; Welsh Government, Planning permission: solar panels (checked 30 October 2026).
- Network connection thresholds (G98 up to 16A per phase — 3.68kW single-phase; larger systems G99): SP Electricity North West; find your operator via the Energy Networks Association.
- Development Bank of Wales, Green Homes Wales: Welsh Government interest-free loans of £1,000 to £25,000 over up to 10 years, including solar PV with or without battery storage (checked 30 October 2026).
- Welsh Government, Nest: eligibility for free home energy efficiency improvements (checked 30 October 2026).
- Cardiff Council, conservation of the built environment (conservation areas, Article 4 directions, listed buildings) and pre-application enquiries (checked 30 October 2026).
- Cardiff Council, Registration opens for Switch Together solar scheme (3 February 2026); Cardiff Capital Region, Switch Together reopens for homes (12 March 2026); Rent Smart Wales, Switch Together solar scheme now open (11 March 2026) and Registration has reopened for the Switch Together scheme (2 June 2026; closes 5 June 2026); Cardiff Council, Solar panel scheme (registration closed 5 June 2026; checked 30 October 2026).
- GOV.UK, Warm Homes Loan Scheme (published 28 October 2026; checked 30 October 2026).