Use of solar panels by the side of tracks to provide power to electric trains could make sense given match-up between peak generation and demand. 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. 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. The UK’s electrified rail routes have all of the features needed to support this kind of PPA-based renewable development, and more. Network Rail is the UK’s single largest electricity consumer, with internal decarbonisation targets and a strong incentive to reduce operational energy costs. Alongside Transport for London (London’s largest electricity consumer), these companies spend around £500m every year on traction power for their trains.