The change means more than 3.3 million homes will have an electricity supply matched by renewable sources including wind, biomass and solar.

The announcement is the largest of its type to date in the UK and significantly increases the number of households in the country backed by 100 per cent renewable electricity.

It comes as a survey of electricity customers shows more than three in five Britons (61 per cent) not already on a renewable tariff, would be likely to change to a renewable electricity supplier if at a reasonable price.

“Climate change is the defining issue of our era, and one that energy customers are increasingly concerned about,” said Michael Lewis, chief executive of E.ON UK.

“We believe large-scale action can make significant change possible and we’re committed to playing a leading role and setting an example for others to follow.”

E.ON is directly supplying a large proportion of this renewable electricity through its own renewable generation fleet, as well as agreements with independent wind generators around the country to directly purchase the electricity produced.

The remaining electricity used by customers is matched with 100 per cent renewable electricity sourced externally through such things as renewable electricity guarantee certificates from the likes of wind, biomass and solar sources. These certificates guarantee that an equivalent amount of renewable electricity was generated to the amount supplied.

E.ON built its first wind farm on Anglesey in 1992 and was a partner in the UK’s first offshore wind farm – Blyth in Northumberland – in 2000.

Today the company owns more than 20 onshore and offshore wind farms in the UK, as well as biomass plants in Scotland and South Yorkshire.