Story highlights New solar array will be largest on a bridge anywhere in the world, say developers

Blackfriars Railway Bridge in central London will carry 4,400 photovoltaic solar cells on roof

PV panels will create 900,000 kilowatt hours of electricity per year, generating 50% of new station's power

New station due for completion in 2012

Work on the world's largest solar bridge has started in central London.

The new solar roof spanning Blackfriars Railway Bridge above the River Thames will cover more than 6,000 square meters when finished, according to developers.

Over 4,400 individual photovoltaic panels are expected to produce around 900,000 kilowatt hours of electricity every year, providing the station with half of its energy needs, according to Solar Century , the UK company installing the solar roof.

Annual CO2 emissions are also expected to be reduced by more than 500 tons.

"It's fantastic to see this project finally come to fruition. Blackfriars Bridge is an ideal location for solar," Derry Newman, chief executive of Solar Century, said in a statement.

"For people to see that solar power is working is a vital step towards a clean energy future," he added.

Built in 1886, the railway bridge is being transformed as part of an upgrade by Network Rail -- the owner and operator of rail infrastructure in the UK -- to the existing Blackfriars station.

"The Victorian rail bridge at Blackfriars is part of our railway history. Constructed in the age of steam, we're bringing it bang up to date with 21st century solar technology to create an iconic station for the city," Lindsay Vamplew, Network Rail's project director for Blackfriars said in a statement.

In addition to the solar panels (manufactured by the SANYO Electric Co. Ltd), the station will also include rain-harvesting systems and sun pipes for natural lighting.

The solar roof and the new station are due to be completed by the summer of 2012.