AN OXFORD ‘green’ energy firm has been acquired in a £340m deal.

Opus Energy, which supplies electricity and gas to small businesses, is now part of Drax Group, which runs the biggest power station in Britain.

Opus, which has its head offices in Banbury Road and other bases in Northampton and Cardiff, was formed in 2002.

Since then it has grown to become the main rival to the so-called ‘big six’ energy providers, employing 850 and supplying more than 295,000 customer sites.

It was ranked sixth in the 2016 Sunday Times Top Track 250, above household names such as McLaren, Caffe Nero, Travelodge, Kurt Geiger and Arsenal Football Club.

FTSE 250 company Drax has been converting generators from coal to biomass, using compressed wood pellets, in order to transfer more of its energy to low-carbon.

Last year, two thirds of electricity Drax generated came from renewables.

Drax Retail chief executive Jonathan Kini said Opus Energy, which counts fast food chain Leon among its customers, was a “perfect” fit with the Drax group.

He said: “The team at Opus is a vibrant group of people and it is an outstandingly well-run business.

“Its niche is supplying small and medium-sized firms, which is a really good market that needs a challenging brand within it.”

He added: “There are five million small and medium-sized enterprises in the UK and they are the beating heart of the economy.

“We see it as a market that has been under-served and aim to bring 100 per cent renewable energy to that market.“

Drax, which employs more than 1,400, last week announced financial results for the year ended December 31.

Earnings before interest, tax, depreciation and amortisation (ebitda) fell by £34m, or 17 per cent, compared to last year.

The company blamed government changes in policy, particularly its decision to apply climate change levy to renewables.

But Mr Kini also said the electricity market in Britain has passed a “tipping point”.

He said: “Until recently, intermittent generators such as wind and solar power have played a relatively small role in the electricity system.

“They are now playing an ever more significant role and the electricity system needs to adjust accordingly.”

Mr Kini added: “We see this as an absolutely pivotal year for Drax and expect profits to be significantly higher.

“The last stage was about conversion to biomass but now with the acquisition of Opus Energy, we can start to develop a retail portfolio.”