Key facts
| Council area | Caerphilly |
| Population | 33,105 (Caerphilly built-up area, usual residents, Census 2021 (ONS, rounded to the nearest five)) |
| Network operator | National Grid Electricity Distribution (South Wales licence area) |
| Main employment areas | Caerphilly Business Park; Pontygwindy Industrial Estate |
| Indicative yield | About 1,012 kWh per kWp a year (south facing, 30 degrees) |
| Nation support page | Grants and reliefs in Wales |
Where businesses are in Caerphilly
- Caerphilly Business Park: An office park near Van Road. In November 2024 the business support hub Welsh ICE opened its new headquarters there at Ty Merlin, which it says is the first A rated building in Wales.
- Pontygwindy Industrial Estate: An industrial estate in Caerphilly. In 2021 marine engineering firm Edwards Diving Services, with about 50 staff there, bought a 9,000 sq ft building next to its premises on the estate.
Large employers and sectors with sites here include:
- Heritage tourism (Caerphilly Castle): Cadw calls Caerphilly Castle the biggest castle in Wales, covering 30 acres, and it has reopened after two years of conservation and refurbishment.
- Small business support and offices: Welsh ICE, which has supported thousands of entrepreneurs in Wales since 2012 with coworking, business support and training, moved its headquarters to Caerphilly Business Park in 2024.
Large, simple roofs on distribution sheds and modern industrial units are usually the quickest and cheapest to fit. Older mill, factory and workshop buildings can work well too, but often need a structural survey first, and roofs from before 2000 may contain asbestos cement: see asbestos roofs.
Grid connection
Caerphilly is served by National Grid Electricity Distribution (South Wales licence area). Almost every commercial system needs G99 approval from the network operator before it is switched on, and the question is usually how much the local network can take back. Where export is limited, a G100 export limitation scheme can let a larger array connect. See G99 and DNO applications.
Planning in Caerphilly
Planning in Caerphilly is decided by Caerphilly council under the Welsh rules. Many non-domestic roofs are covered by Welsh permitted development, with conditions, but not within 3 km of an airport or aerodrome or on listed buildings.
Points that come up locally:
- Caerphilly Castle in the town centre is a scheduled monument (Cadw GM002), and the scheduled area includes land around the remains, so roofs in its setting may get closer scrutiny.
Our planning permission guide sets out the rules.
What a business roof in Caerphilly could generate
Modelled with PVGIS for the town centre, a south-facing roof at 30 degrees produces about 1,012 kWh per kWp a year.
| Item | Illustrative figure |
|---|---|
| System | 100 kWp, south facing at 30 degrees |
| Installed cost | £900 per kWp, so £90,000 excluding VAT |
| Generation | About 101,200 kWh a year |
| Used on site | 70% at 24p = £17,002 saved |
| Exported | 30% at 5p = £1,518 earned |
| Total a year | About £18,520 |
| Simple payback | About 4.9 years before tax relief |
Illustrative, not a quote: the same sums as our commercial solar calculator. A company paying corporation tax can usually shorten the payback with capital allowances.
Funding and support
- Development Bank of Wales Green Business Loan Scheme: Discounted fixed interest rate green business loans for energy efficiency measures and low carbon projects, with renewables including solar PV listed as typical eligible projects; capital repayment holidays are available and the loan term is linked to the project's payback. Limited companies, sole traders and partnerships must be based in Wales, have traded for at least two years and have at least one set of filed annual accounts. A Business Wales grant of up to 50% of the cost of a detailed energy audit, to a maximum of £10,000 (£20,000 total costs), is also offered. Check the scheme's own page for eligibility and closing dates.
National reliefs apply too: see grants and reliefs in Wales.
Solar across Caerphilly
At the end of 2025, Caerphilly had 4,974 solar PV installations with 72.3 MW of capacity, up 17% since 2020, according to government figures. The Caerphilly page has the full local figures and how they compare.
Nearby towns
- Bargoed, about 8 miles away
- Newport, about 9 miles away
- Penarth, about 10 miles away
- Cwmbran, about 10 miles away
Sources
- ons.gov.uk: census2021
- ons.gov.uk: datadownload.xlsx
- caerphilly.observer: welsh ice celebrates launch of its new base
- caerphilly.observer: edwards diving services gets lloyds bank support
- cadw.gov.wales: caerphilly castle
- gov.uk: growth and local jobs top of the agenda
- caerphilly.observer: latest plans for citys high tech cluster could
- gov.uk: maps of celtic freeport tax sites
- businesswales.gov.wales: about enterprise zones
- developmentbank.wales: green
- Yield: PVGIS 5.3 (European Commission Joint Research Centre), SARAH3 data, 14% system losses, for the town centre, modelled 4 November 2026.
- Council area figures: DESNZ, renewable electricity by local authority 2014 to 2025.
Frequently asked questions
Who is the electricity network operator in Caerphilly?
National Grid Electricity Distribution (South Wales licence area). Most commercial solar systems need its G99 approval before they are switched on. The operator follows the postcode, so confirm yours with the Energy Networks Association postcode tool.
How much would a 100 kWp solar system generate in Caerphilly?
About 101,200 kWh a year for a south-facing roof at 30 degrees, modelled with PVGIS for the town centre. At 70% used on site at 24p and the rest exported at 5p, that is worth about £18,520 a year. Your own roof, orientation and use will change this.
Can a business in Caerphilly get a free solar survey?
Yes. Answer six short questions and we match the site with one MCS certified installer, who surveys it on site or by video call. It is free, with no obligation. Get a free survey.
Related pages
- Caerphilly4,974 installations, 72.3 MW of solar and about 949 kWh per kWp a year for a south-facing roof.
- WalesNGED and SP Energy Networks connections, Planning Policy Wales and Welsh permitted development, the Welsh rates exemption to 2035, and farm, factory and port roofs.
- Commercial solar calculatorEstimate commercial solar savings and payback, with the generation, price and cost assumptions shown and sourced, and the limits of a simple estimate explained.
- WalesCurrent solar support in Wales for businesses, farms, public bodies and community groups, with rates, planning and official contacts.
- Planning permissionPermitted development for commercial rooftop solar and car park canopies in England, prior approval, heritage limits, ground-mounted schemes and the other UK nations.