Octopus Energy has posted a £5 million operating loss despite experiencing “rapid growth” in both customers numbers and turnover.

The figure for the 12 months to the end of April 2018 represents an improvement on the previous year when the supplier reported a £6.3 million loss. On a gross basis, the company moved from a £1.2 million loss to a £5.8 million profit.

Revenues nearly tripled from £35 million to £129 million, while customer numbers more than doubled from 78,000 to 199,000.

Octopus Energy now has half a million customers on its books after acquiring roughly 95,000 from Iresa through the supplier of last resort process in July. Ofgem recently awarded the firm £13.2 million to cover related costs, including £10.9 million for honouring customers’ outstanding credit balances.

The company also gained a further 22,000 customers in September with the purchase of Affect Energy.

Octopus Energy founder and chief executive Greg Jackson, said: “The shape of the market, the system and the way customers see energy is evolving rapidly, and we have created an energy technology company to drive this change.  Our performance across the year, and subsequently, demonstrates the success of our approach.

“In only our second full year of trading, we have seen rapid growth, with customer numbers now at 500,000.  This shows the appetite for 100 per cent renewable electricity, with long-term fair and transparent pricing. We have also shown it’s possible to scale rapidly while giving unparalleled customer service”.

Octopus Energy recently came top in the annual customer satisfaction survey held by Which?.