Commercial building solar panels across Swansea

What the data says about Swansea

Modelled yield varies across Swansea: Mumbles comes out at 921 kWh per kWp a year against 881 at Neath. On a 210 kWp commercial roof that gap is about 8,400 kWh a year.

Across the 2 authorities our Swansea towns sit in, the Valuation Office Agency lists 2,540 office and 3,270 retail properties, 210 of them large-format stores and retail warehouses. Source: Valuation Office Agency, Non-domestic rating: business floorspace, 31 March 2025 (published December 2025), counts and floorspace by special category code and local authority district, England and Wales.

The planning database records no roof-mounted commercial schemes in the districts we cover in Swansea. That usually means arrays have gone in below its reporting threshold, not that none exist: many commercial roofs carry less than a megawatt and never appear.

Connections across the county run through National Grid Electricity Distribution. Anything above 3.68 kW per phase needs a G99 application, and the export limit offered shapes the design, so the question is asked before the array is sized.