The project, developed alongside climate change charity 10:10, aims to develop renewable energy sources in order to reduce carbon emissions and future transport running costs.

Riding Sunbeams is currently installing 135 solar panels on derelict land near Aldershot station on the London Waterloo - Alton line, which is managed by South Western Rail (SWR). The 30kWp ‘First Light’ demonstrator photovoltaic array will connect to an ancillary transformer on the traction system to supply power to lights and signalling equipment.

Riding Sunbeams and 10:10 will then use the test data to design and test systems which can directly supply solar power to the dc traction network.

The project is a collaboration between 10:10, Community Energy South and infrastructure manager Network Rail, alongside a wider consortium of specialist engineering and renewable energy consultants and university departments. The project is funded by Innovate UK and the Department for Transport.

Riding Sunbeams says solar traction power could provide around 10% of the energy needed to power trains on Britain’s third-rail 750V dc electrified lines every year.

In 2017, Riding Sunbeams carried out six site-specific feasibility studies at locations across southwest Britain, looking at how small, community-owned solar farms alongside railways could supply renewable electricity directly to the tracks to power trains. Riding Sunbeams says the study found that solar traction power was technically and financially feasible.

“Solar traction power solves two problems for decentralised renewable energy generation: it provides a new way to finance unsubsidised solar in Britain, and offers a way to circumvent grid capacity constraints,” the charity says. “Meanwhile, it gives rail operators a chance to reduce traction electricity bills, cut carbon emissions and potentially deliver completely new kinds of social benefits to lineside neighbours.”

While the project initially explored using a dc-dc inverter to develop a direct connection from solar panels to traction substations on the dc rail network, Riding Sunbeams found this wasn’t feasible due to the unavailability of the required equipment.

Instead, it will use existing equipment to connect into the 33kV ac feeder systems that carry power from the grid supply points (GSPs) to the substations, which supply dc power to the third-rail.

“This approach also helps overcome the big technical challenge for rail renewable traction power: the intermittency of both the load and supply. Using this method, we will not usually need to integrate storage,” Riding Sunbeams says.

“The rail industry plays an important role in reducing carbon emissions. SWR has reduced its emissions by 33% over the last 12 months and is continuing to install renewables, and other technologies, to cut our carbon emissions by 60% overall within the next five years,” says SWR’s head of sustainability, Ms Amelia Woodley. “With the recent passing of net zero emissions legislation in Britain, there’s never been a better time to partner with the Riding Sunbeams to change the way the rail industry responds to this global challenge.”