The planning system in the UK, which differs slightly across the four devolved nations, is a plan-led system. In Wales, any new development is guided by planning policy set out in local development plans. When a planning application for a new development is submitted, to be successful it must follow the planning policies for the area.
Large infrastructure projects over a certain size (eg offshore wind developments and power plants over 350 megawatts) are decided by the UK Government through the Nationally Significant Infrastructure Projects (NSIP) process. This is a separate system from town and country planning, which is set out in the Planning Act 2008 and managed by the Planning Inspectorate.
Other large infrastructure projects (eg energy generation projects less than 350 megawatts, all onshore wind projects, airports and railways) are decided by the Welsh Government through the Developments of National Significance (DNS) process.