If you live in a 3-bed semi-detached house in Cardiff with a south-facing roof, you're in a prime position to cut your electricity bills with solar panels. This scenario is designed for typical UK homeowners paying around £1,200 a year for energy. We've calculated exactly what a system on your 30m² roof could save—no jargon, just clear numbers you can trust.
Your Solar Savings in Cardiff
For a typical 3-bed semi-detached home in Cardiff with a 30m² south-facing roof, solar panels are a smart investment. Based on your current annual electricity bill of £1,200, a 5.4 kWp system could generate 5,238 kWh per year—more than enough to cover most of your daytime usage and earn you money through the Smart Export Guarantee.
How Much Can You Save?
Your annual savings of £733 come from using the solar electricity you generate during the day, reducing what you’d otherwise pay to your supplier. On top of that, you can earn around £220 per year by exporting surplus power back to the grid. That’s a combined benefit of over £950 in the first year alone.
Installation Costs and Payback
The typical cost for a 5.4 kWp system is £5,940 (including installation and VAT at 5%). With annual savings and export income, your system would pay for itself in 8.1 years. Solar panels last 25+ years, so you’ll enjoy free electricity for the majority of their lifespan.
Environmental Impact
By switching to solar, you’ll save approximately 1.2 tonnes of CO2 per year—equivalent to planting 55 trees annually. It’s one of the most effective ways to reduce your household’s carbon footprint.
Your System at a Glance
| Metric | Value |
|---|---|
| System size | 5.4 kWp |
| Annual generation | 5,238 kWh |
| Annual savings | £733 |
| Bill reduction | 43% |
| Install cost | £5,940 |
| Payback period | 8.1 years |
| CO2 saved | 1.2 tonnes/yr |
| Export income | £220/yr |
Note: A 5.4 kWp system on your 30m² roof could generate 5,238 kWh per year, saving you approximately £733 annually. The system would pay for itself in around 8.1 years.
Grants and Support
You may be eligible for the Boiler Upgrade Scheme if you’re also considering a heat pump, but solar panels themselves aren’t covered. Check the Energy Saving Trust’s solar panel advice for more on funding and installation.
Is Solar Right for Your Home?
Solar panels work best on south-facing roofs with little shading. Cardiff’s average sunlight hours are good for the UK, making it a solid location for generation. To get a personalised quote, use the MCS certified installer finder.
Frequently Asked Questions
How long do solar panels last?
Most solar panels come with a 25-year performance warranty, and they often continue generating electricity for 30 years or more. Inverters may need replacing after 10-15 years, but the panels themselves are very durable.
Will solar panels work on cloudy days?
Yes, solar panels still generate electricity on cloudy days, though at a reduced rate. Cardiff’s climate is fine for solar—the UK gets enough diffuse light to make panels worthwhile year-round.
Do I need planning permission?
In most cases, solar panels on a house in Cardiff are permitted development and don’t need planning permission. However, if you live in a listed building or conservation area, check with your local council first.
How these numbers were calculated
These calculations use typical UK solar generation data from the Energy Saving Trust, adjusted for Cardiff's solar irradiance. We assumed a 30m² south-facing roof, a 5.4 kWp system, and an annual electricity bill of £1,200. Savings include avoided grid electricity at 28p/kWh and Smart Export Guarantee income at 15p/kWh, based on Ofgem rates.
Sources
- Energy Saving Trust — Solar panels
- Ofgem — Smart Export Guarantee
- MCS Certified — Find an installer
