Sian Berry, the Green Party's candidate for the London mayoralty, has echoed her Labour and Conservative counterparts' calls for Transport for London (TfL) to embrace solar as part of her election manifesto.

Berry is to unveil her energy policy later this morning at Vauxhall Bus Station, but one of her aims is for TfL's Crossrail project to be fully powered by renewable sources.

Berry's plans revolve around the establishment of a London Energy Company, similar to plans put forward by Sadiq Khan earlier this month but different in that this entity would be a subsidiary of TfL.

That company's aim would be to install solar and other renewables across TfL's 5,700-acre estate in London, including on the rooftops of offices and train stations. Ground-mount solar farms would be developed on brownfield sites in London's fringe.

Such a company, Berry has claimed, would free up more of TfL's finances to be invested in infrastructure by reducing its exposure to energy price volatility and high energy bills.

TfL is one of the country's highest consumers of energy and its yearly bill now tops £140 million. Its demand is expected to spiral further over the next four years, exceeding 1,900GWh by 2020.

The transport body currently derives around 1% of its energy demand from renewable sources and Berry said this could soar to around one-fifth from solar power alone.

“There is huge potential in London for a wide range of low and zero-carbon technologies to be used to generate heat and electricity from the sun, the wind, the ground and air using heat pumps, gas created from waste, and from London’s tides and river flows,” Berry said.

“Unfortunately Boris Johnson hasn’t even bothered to push solar PV. That means London has missed out on the UK’s solar revolution, with cities in the north of England and even Scotland installing more panels per home than London, even though we get more sun in the south. Our London Energy Company will work to turn this situation around.”

She added: “Transport for London is already becoming a property developer with its own land to shore up its finances. We believe it should also become an energy developer. As with the property development, a Green Mayor would ensure it balances revenue generation with wider social and environmental objectives – in this case, increasing renewable energy generation and supplying low-cost energy to Londoners.”