How can we connect solar photovoltaics (PV) directly to railways to power electric trains? That’s the question my charity 10:10 and researchers at Imperial College’s Energy Futures Lab are trying to answer. Electric trains are by far the best long distance transport mode when it comes to carbon emissions – at least when their electricity comes from renewable sources like solar or wind. But the UK’s ageing power network poses a significant challenges to any bid to decarbonise road and rail that relies on the grid. There are now swathes of the British countryside where it is impossible to plug in any new solar, wind or hydropower without being hit with a whopping bill for the full costs of local network reinforcement. Faced with this constraint, and squeezed by government subsidy cuts, UK solar developers have started to focus on ways to generate power directly for consumption, rather than exporting it to the grid. With the right customers, solar developers can offer lower tariffs than the grid, while still earning more for their power than they would get from exporting it. Solar giant Lightsource, for example, recently signed a 25 year power purchase agreement (PPA) with Belfast airport that underwrote a neighbouring £5m solar farm, using a private wire to supply a quarter of the airport’s electricity needs. As an industrial client with high on-site daytime energy use and a structural reason to stay put, Network Rail has all of the features needed to support this kind of approach.