A new assessment of Britain's commercial building stock suggests the country is sitting on a vast, largely untapped source of clean electricity: the rooftops of warehouses, factories, offices and retail units. According to reporting from Construction Management Magazine, the solar generation potential of UK commercial roof space is equivalent to roughly 20 Hinkley Point C nuclear power stations, a comparison that underlines just how significant this overlooked asset could be to the country's energy mix. Hinkley Point C, the nuclear plant under construction in Somerset, has become something of a byword for large-scale, dependable low-carbon power in public discourse, and its use here as a benchmark is telling. Nuclear projects of that scale take years, sometimes decades, to plan, fund and build, and Hinkley itself has been dogged by delays and spiralling costs. Commercial rooftop solar, by contrast, uses existing structures and requires no new land, no lengthy grid connection queues on the scale of major infrastructure projects, and considerably shorter lead times. The suggestion that dormant roof space could deliver comparable generating capacity to twenty such plants is a striking illustration of an opportunity that has so far gone largely unrealised. For the UK's net zero ambitions, the implications are significant. Ministers have repeatedly stressed the need to accelerate deployment of renewable generation to meet legally binding decarbonisation targets, while also reducing reliance on imported gas and insulating consumers from volatile wholesale energy prices. Rooftop solar on commercial buildings offers a route to new capacity that sidesteps some of the planning and land-use disputes that have slowed ground-mounted solar farms and onshore wind in parts of the country. Warehouses and distribution centres, in particular, tend to have large, flat, unshaded roof areas that are well suited to panel installation, and many already carry significant electricity loads from refrigeration, lighting and increasingly from EV charging infrastructure for fleet vehicles. That last point matters for the wider transition. As logistics operators and retailers electrify their vans and lorries, on-site solar generation paired with battery storage could help businesses manage the additional demand from charging without straining local grid connections, a growing concern in parts of the country where capacity is constrained. Distributed generation of this kind also reduces transmission losses and can ease pressure on the wider network at peak times. Realising anything close to this potential would nonetheless require sustained investment, supportive planning policy and finance mechanisms that make it straightforward for landlords and occupiers to install panels, particularly where roofs are leased rather than owned outright. The comparison to Hinkley Point C is intended to grab attention, but the underlying message is a familiar one in the UK energy debate: significant low-carbon capacity may already be available on buildings the country has already built, waiting for the right incentives to unlock it.