Cardiff is the largest commercial solar market in Wales and, for a rooftop installer working from Swansea, the most consistent source of enquiries over 500 kWp. The combination of large, relatively new flat-roofed commercial and industrial stock, high grid electricity prices, and genuine capital availability among owner-occupiers makes the CF postcodes a reliably productive market.
Solar yield in Cardiff
PVGIS irradiation data for Cardiff (CF10) returns a typical annual yield of 945 to 960 kWh per kWp installed. That is fractionally below Swansea at 950 and materially better than Manchester at 920. For a 250 kWp system, the Cardiff yield translates to approximately 237,500 kWh per year under standard conditions.
The practical implication: a commercial buyer in Cardiff can model essentially the same economics as the South Wales average without adjustment. The figures below use 950 kWh/kWp throughout.
Key commercial locations and business parks
Cardiff Business Park (CF23) and Capital Business Park (CF3) together account for a significant share of the CF commercial rooftop stock. Both are dominated by 1990s and early-2000s single-storey warehouse and light industrial units, many with south-facing pitched steel roofs that suit trapezoidal-clad solar well.
Treforest Industrial Estate (CF37), nominally in Pontypridd but within commuting distance and the same DNO zone, carries some of the oldest industrial stock in South Wales — several units have been reroofed in the last decade, creating clean flat surfaces ideal for ballasted arrays.
Wentloog Corporate Park (CF3) near Newport Road is the most active regeneration zone in the east of the city. New-build logistics units here are typically built to the grade of specification that makes solar straightforward: structural loading pre-rated for 15 kg/m2 ballasted arrays, south or east/west roofs at 5 to 10 degrees, and incoming supplies of 800 kVA or more.
Cardiff Bay / Butetown carries the waterfront commercial stock: SA1-style mixed-use regeneration with PBSA and office development. Flat roof orientation varies, but any south-facing roof with clear sky access is viable.
Worked example: 300 kWp logistics unit, Wentloog
- Installed cost: approximately £240,000
- Annual generation at 950 kWh/kWp: 285,000 kWh
- Self-consumption at 75% at 29p/kWh blended: £62,119
- Export at 25% at 12p SEG: £8,550
- Year-one benefit: £70,669
- Simple payback: 3.4 years
- Post-tax payback with 100% Annual Investment Allowance: 2.5 years
At a 22% post-tax internal rate of return over 25 years, this stacks up clearly against any alternative capital deployment.
Planning considerations in Cardiff
Most commercial rooftop solar in Cardiff is permitted development under Welsh PDR rules, provided the system is more than 10 metres from the building edge and does not exceed 1 MW. The Welsh permitted development threshold for commercial installations is meaningfully more permissive than England, which makes large rooftop arrays straightforward.
Exceptions to watch for:
- Conservation areas in Roath, Pontcanna, and Canton require planning permission for visible front-elevation installations
- Listed buildings in the city centre (including several CF10 commercial properties) need listed building consent regardless of roof orientation
- Cardiff Bay Enterprise Zone has its own design guide; consult the Cardiff Capital Region planners before submitting any G99 application in CF10 5
DNO connection in Cardiff
Cardiff is served by National Grid Electricity Distribution (NGED), formerly Western Power Distribution. G99 Type A connection timelines in CF postcodes are currently running at 12 to 18 weeks for export-limited systems below 1 MW, which is slightly longer than the Swansea average. FLD submits the G99 application as part of our standard commercial process, and we have learned to programme the Cardiff timeline into project schedules.
Ynni Cymru grants for Cardiff businesses
Welsh Government’s Ynni Cymru capital grant programme covers commercial solar across all Welsh postcodes including CF. Awards range from £25,000 to £1 million per project, with the 2026-27 pot at approximately £10 million. Eligibility requires the business to be trading in Wales, and the application must be submitted before procurement. FLD can provide the technical specification pack required for a grant application.
Getting a Cardiff commercial solar quote
FLD engineers visit Cardiff regularly. We can turn around a site survey and fixed-price proposal within five working days of visiting. Call Paul directly on 01792 680611 or submit an enquiry via the contact page.