Shell announced in the summer of 2023 that it would sell its domestic energy business in the UK to Octopus and exit the market, according to Uswitch's guide to the big six suppliers1. The transfer process was completed on 1 December 20231.
The business had been built on First Utility, described as one of the more prominent challenger energy brands, which Shell acquired and renamed Shell Energy1. With the backing of one of the world's most recognisable companies, Shell Energy had emerged as a legitimate competitor to the dominant suppliers before the sale was announced1. The guide does not report the price paid, the number of customers transferred, or the terms of the deal.
The exit formed part of a wider reshaping of the supplier market. SSE agreed in December 2019 to sell its customer portfolio to OVO1, and npower agreed in 2021 to move its customer base to E.ON, which shifted those customers to a sub-brand called E.ON Next1. Octopus, which entered the UK energy market in 2016, overtook British Gas in late 2023 to become the UK's largest electricity supplier1. The company claims nearly one million people switched to it during 20241. As of July 2026, Octopus is the UK's largest energy supplier by market share, supplying 25.7% of electricity customers and 25.9% of gas customers1.
The guide lists the big six as of July 2026 in order of size: Octopus Energy, British Gas, E.ON Next, OVO Energy, EDF Energy and ScottishPower1. British Gas remains the UK's largest gas supplier as of March 2026 and its second-largest electricity supplier1. E.ON Next holds third place primarily through the npower acquisition completed in 20211. OVO is fourth, largely through acquiring SSE's 1.5 million customers in 2019, and is due to be acquired by E.ON in the near future1. EDF, French-owned and state-owned, has been part of the big six since 20021. ScottishPower, Spanish-owned despite its name, remains sixth as of March 20261. The guide states that as of April 2026 there were 17 energy suppliers operating in the UK, according to Ofgem1.
"in the summer of 2023, Shell announced it would be selling its domestic energy business in the UK to Octopus and exiting the market"
Why it matters for households
A household supplied by Shell Energy did not lose its supply when the business changed hands. The guide notes that when a supplier stops trading, Ofgem moves customers to a different supplier, and that a switch does not change the pipes and cables delivering the energy, only who charges for it1. The Shell Energy sale was a commercial transfer rather than a supplier failure, but the practical effect for the household was the same: the same gas and electricity, a different company on the bill.
The wider consequence is concentration. The guide frames the main risk of a market dominated by a small number of firms as the potential for uncompetitive tariffs and high energy bills1. For a home's energy independence, the relevant question is how many suppliers compete for its custom and on what terms. The guide records that smaller suppliers often offer deals on par with, or in some cases cheaper than, the big six, and that a common fear about them is that they are more likely to go out of business1. It also notes that there is very little to prevent anyone setting up an energy supply business, and that many smaller companies have gone out of business in recent years1.
What happens next
The guide states that OVO Energy is due to be acquired by E.ON in the near future1. No completion date is given.
Sources1 cited
- Big six energy suppliers in the UK - Uswitch, uswitch.com