The Big Six were Great Britain's largest retail suppliers of gas and electricity, who dominated the market following liberalisation in the late 1990s. By 2002, six companies – British Gas, EDF Energy, E.ON, RWE npower, Scottish Power and SSE – had emerged from the 15 former incumbent monopoly suppliers (the 14 regional public electricity suppliers and British Gas).
In 2008, the Big Six still had over 99% of domestic and small business customers. They were vertically integrated in electricity, owning sufficient generation capacity to supply all their customers; while in gas, only Centrica (British Gas) owned production facilities. By the third quarter of 2019, after efforts by the regulator Ofgem to promote competition, their combined share in Great Britain was 70% for electricity supply and 69% for gas. The purchase of SSE's retail business in January 2020 by OVO Energy, a competitor founded in 2009, marked the end of the original Big Six.
The companies In 2008, the six companies were: Supplier Parent Other brands Former brands (including retail/supply divisions of former regional electricity boards)Notes British Gas Centrica Scottish Gas EDF Energy Électricité de France SEEBOARD, SWEB Energy, London Electricity E.ON UK E.ON East Midlands Electricity, NORWEB, PowergennpowerMidlands Electricity, Northern Electric, Yorkshire ElectricityCustomers migrated to E.ON Next between 2020 and 2021 Scottish Power Iberdrola (from 2007) MANWEB SSEScottish and Southern, Southern Electric, SWALEC, Scottish HydroCustomers migrated to OVO Energy between 2020 and 2023
2014–2016 competition investigation In June 2014, energy market regulator Ofgem referred the energy industry to the Competition and Markets Authority (CMA). The authority investigated the "six large energy firms" and published its report in June 2016. For the retail market, the report recommended:
Removal of the requirement imposed by the 2014 Retail Market Review that limited suppliers to offering no more than four tariffs Establishment by Ofgem of a database of customers who have been on a "standard variable tariff" for three years or more, which competitors could use to contact those customers A temporary price cap for customers on prepayment meters Measures to support price comparison websites in the energy market.
Consolidation to Big Five In 2017, SSE and Npower announced a merger of their retail businesses, but this was scrapped in 2018.
Just after the failed SSE-Npower merger in late 2018, it was reported that a consolidation to the Big Five would still occur, as Npower would be acquired by default by E.ON due to the already-planned asset swap by the respective German parents, Innogy and E.ON. This was completed in 2019.
Alternatives to the Big Six In December 2014, Utility Warehouse, part of FTSE 250-listed company Telecom Plus became the UK's biggest independent energy supplier through a £218m deal to buy 770,000 existing customers from npower. In September 2014, First Utility (since rebranded as Shell Energy) announced it was the first independent utility supplier to reach the milestone of 1m customer accounts for gas and electricity – the equivalent of 550,000 customers, which made it the seventh-largest energy supplier in the UK and the country's biggest independent energy provider. In June 2015, a Cornwall Report stated Opus Energy had broken the dominance of the 'Big Six' energy suppliers in the business market.
The Competition and Markets Authority published an investigation into the energy supply market in June 2016, following a referral by Ofgem in June 2014. The report identified 34 suppliers of both electricity and gas to households, and described the three largest suppliers outside the Big Six as "mid-tier suppliers"; these were First Utility, OVO Energy and Utility Warehouse. Other significant suppliers (each with more than around 1% market share) were Co-operative Energy, Extra Energy and Utilita Energy (specialising in pre-pay customers). The combined market share of suppliers outside the Big Six had increased from less than 1% in 2011 to around 13% in the first quarter of 2016.
Since 2009, other entrants into the market include a number of new energy companies including Bulb Energy, Good Energy, Ecotricity, and Octopus Energy. Many of these newer entrants are seeing significant growth in customer numbers, in part due to their greater commitment to renewable energy and, in the case of Co-op Energy, community renewable energy projects.
The energy regulator Ofgem maintains a list of all licensed electricity suppliers and distribution network operators.Ofgem, All Electricity licensee's , last updated 27 May 2021, accessed 9 June 2021
Local authority-owned companies Three of the alternative energy companies have been owned by local authorities. The first such company since 1948 was Robin Hood Energy, owned by Nottingham City Council, which entered the market in 2015. Bristol Energy, also launched in 2015, was owned by Bristol City Council. Both Robin Hood Energy and Bristol Energy were available to consumers throughout the country until their demise in 2020.
In January 2020, London Power was launched by the Mayor of London. Contrary to the other two companies, it only provides gas and electricity to London homes. London Power is not itself an energy supplier, instead it is a partnership between the Greater London Authority and a providing partner, currently Octopus Energy.
Defunct competitor companies Before 2021 By January 2019, ten small energy suppliers had ceased trading or been taken over by others, and others followed similar paths until the market turbulence in the autumn of 2021. + 2016 to 2020CompanyCeased tradingCustomers (approx.)Customers transferred toAffect Energy22,000Octopus Energy (acquisition)Breeze Energy18,000British GasBrilliant Energy17,000SSEBristol Energy155,000 domestic,4,000 businessBusiness: Yü Energy Domestic: Together EnergyEconomy Energy235,000OVO EnergyENGIE UK70,000Octopus Energy (acquisition of ENGIE's domestic UK customers)Eversmart Energy39,000 domesticUtilita Energy LimitedExtra Energy108,000 domestic,21,000 businessScottishPowerFlow Energy130,000Co-op Energy (acquisition)Brand continued until acquired by Octopus in 2019Future Energy10,000Green Star EnergyGB Energy Supply160,000Co-op Energy (acquisition)Brand continued until acquired by Octopus in 2019Green Star Energy200,000Shell Energy (acquisition)Green Star was a subsidiary of Canada's Just EnergyIresa100,000Octopus EnergyOneSelect36,000Together EnergyOur Power31,000Utilita EnergyRobin Hood Energy112,000 domestic,2,600 businessBritish GasSolarplicity60,000EDF EnergySpark Energy290,000OVO EnergyTonik Energy130,000ScottishPowerToto Energy134,000EDF EnergyUsio Energy7,000First UtilityYorkshire Energy74,000ScottishPowerNational Gas and Power Limited25/07/2018 22,000 Hudson Energy Gen4U 13/09/2018 500Octopus EnergyCardiff Energy Supply 09/08/2019 800 SSEUttily Energy15/10/2019 280 business customersTotal Gas and PowerGnERGY 18/03/2020 9,000 Bulb Energy Go Effortless Energy 03/09/2020 2,500 Octopus Energy
2021–2022 Sharp increases in wholesale gas prices in summer and autumn 2021, and a consequent increase in wholesale electricity prices, led to further collapses. High prices continued into 2022. Ofgem continued to arrange for customers of those companies to be transferred to other suppliers, but when Bulb Energy failed in November 2021 a different approach was needed: with 1.7million customers, it was the seventh biggest supplier company. Bulb was placed in "special administration" and the UK government undertook to cover its losses while a sale or restructuring was organised, with a potential cost to taxpayers of £1.7billion.
+2021-2022CompanyCeased tradingCustomers (approx.)Customers transferred toZog Energy 11,700EDF EnergySimplicity Energy50,000British Gas EvolveGreen Network Energy360,000EDFAmpoweruk Ltd 2 November 2021, finalised 3 November 600 or 2,600 Yü Energy Omni Energy3 November 2021under 10,000UtilitaMA Energy 3 November 2021under 10,000SmartestEnergy Business LimitedNeon Reef16 November 202130,000British GasSocial Energy Supply16 November 20215,500British GasCNG-Power3 November 2021 under 10,000Pozitive EnergyZebra Energy 3 November 2021under 10,000British GasBluegreen1 November 2021, finalised 3 November5,600British GasAvro Energy22 September 2021580,000Octopus EnergyColorado Energy13 October 202115,000Shell EnergyDaligas14 October 20219,000Shell EnergyENSTROGA29 September 20216,000E.ON NextGreen Supplier Limited22 September 2021255,000Shell EnergyGOTO Energy 18 October 202122,000Shell EnergyHub Energy9 August 20216,000 domestic, 9,000 othersE.ON NextIgloo Energy29 September 2021179,000E.ON NextMoneyPlus Energy7 September 20219,000British GasPeople's Energy14 September 2021350,000 domestic, 1,000 othersBritish GasPFP Energy7 September 202182,000 domestic, 5,600 othersBritish Gas PFP was Places for People Energy 2014–2017Pure Planet13 October 2021235,000Shell EnergySymbio Energy29 September 202148,000E.ON NextTogether Energy 18 January 2022176,000British GasUtility Point14 September 2021220,000EDF EnergyBulb Energy23 November 20211,700,000Special Administration ProcessOctopus EnergyOrbit Energy26 November 2021, finalised 29 November65,000Scottish PowerEntice Energy26 November 20215,400Scottish PowerXcel Power Ltd 18/02/2022 274 Yü Energy Whoop Energy 18/02/2022 262Yü Energy
2023–2024 No significant company failures.
2025 onwards +2025 onwardsCompanyCeased tradingCustomers (approx.)Customers transferred toRebel Energy 2 April 202580,000 domestic and 10,000 business customersBritish Gas
See also Energy in the United Kingdom Energy policy of the United Kingdom Energy switching services in the UK Electricity sector in the United Kingdom
References