Indicative 4 kWp install in Cardiff: £6,700–£7,850. Region: North / Wales (×0.96). Annual irradiance: ~940 kWh/kWp.
What Cardiff homeowners actually pay
Cardiff solar installs come in slightly below the UK average, with payback close to Bristol's because irradiance is similar (~940 kWh/kWp/yr). A 3-bed terrace in Roath or Canton lands £5,400–£6,900 for a 4 kWp install. The student-rental market in Cathays drives steady demand for landlord-led installs, which keeps the contractor market competitive. Bay-area apartment stock is the outlier — building-management consent and shared cabling add days that don't show up in a typical terrace job.
Local notes for Cardiff
Cathays and Roath have a high share of student HMOs — landlord-led installs often pair with EV chargers.
Bay-area apartments need building-management consent before scaffolding can go up.
Irradiance ~940 kWh/kWp/yr — same band as Bristol.
Welsh Government's Nest scheme can fund full installs for low-income households.
Field notes
Cathays HMOs: solar + EV charger combo is the most-quoted job.
Bay-area flats: factor 4–6 weeks for building-management approval.
DNO is NGED — same as Bristol.
Frequently asked questions
Are HMO solar installs in Cardiff different to standard homes?
Yes — the consumer-unit upgrade and AC isolator must satisfy HMO licensing (BS 5839 fire-detection isn't affected, but the EICR cycle usually is). Coordinate with your annual landlord paperwork.
Is solar PV worth it in Cardiff?
Yes — Cardiff has South Wales' best irradiance band and competitive installer pricing. A 4 kWp install typically pays back in 9–12 years, slightly faster with battery if your import tariff is high.
Do I need planning permission in Cardiff?
Almost never for suburban houses — domestic solar is permitted development in Wales. Listed buildings in Llandaff and conservation areas in Cathays Park are the main exceptions.