Big Six energy suppliers explained

The Big Six were the United Kingdom'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).^[1]

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.^{[2] [3]} 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.^[4]

The companies

Source:

Supplier	Parent	Other brands	Former brands(including retail/supply divisions of former regional electricity boards)
British Gas	Centrica	Scottish Gas
EDF Energy	Électricité de France		SEEBOARD, SWEB Energy, London Electricity
E.ON UK including npower	E.ON		Northern Electric, Midlands Electricity, East Midlands Electricity, NORWEB, Powergen, Yorkshire Electricity
OVO Energy			Following purchase of SSE's retail business in 2020
Scottish Power	Iberdrola (from 2007)		MANWEB
SSE			Scottish and Southern, Southern Electric, SWALEC, Scottish Hydro

2014–2016 competition investigation

In June 2014, energy market regulator Ofgem referred the energy industry to the Competition and Markets Authority (CMA).^[5] The authority investigated the "six large energy firms" and published its report in June 2016.^[6] For the retail market, the report recommended:^[7]

• 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,^[8] but this was scrapped in 2018.^[9]

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.^[10] This was completed in 2019.^[11]

Alternatives to the Big Six

In December 2014, Utility Warehouse, part of FTSE 250-listed company Telecom Plus^[12] became the UK's biggest independent energy supplier through a £218m deal to buy 770,000 existing customers from npower.^[12] In September 2014, First Utility^[13] (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.^[13] In June 2015, a Cornwall Report stated Opus Energy^[14] had broken the dominance of the 'Big Six' energy suppliers in the business market.^[14]

The Competition and Markets Authority published an investigation into the energy supply market in June 2016,^[15] following a referral by Ofgem in June 2014.^[15] 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.^[16] 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).^[16] The combined market share of suppliers outside the Big Six^[17] had increased from less than 1% in 2011 to around 13% in the first quarter of 2016.^[17]

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.^[18]

The energy regulator Ofgem maintains a list of all licensed electricity suppliers and distribution network operators.^[19]

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.^[20]

Defunct competitor companies

Before 2021

By January 2019, ten^[21] 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 2020

Company	Ceased trading	Customers (approx.)	Customers transferred to
Affect Energy		22,000	Octopus Energy (acquisition)^[22]
Breeze Energy		18,000	British Gas
Brilliant Energy		17,000	SSE^[23]
Bristol Energy		155,000 domestic, 4,000 business	Business: Yü Energy^[24] Domestic: Together Energy^[25]
Economy Energy		235,000	OVO Energy^[26]
ENGIE UK		70,000	Octopus Energy (acquisition of ENGIE's domestic UK customers) ^[27]
Eversmart Energy		39,000 domestic	Utilita Energy Limited^[28]
Extra Energy		108,000 domestic, 21,000 business	ScottishPower^[29]
Flow Energy		130,000	Co-op Energy (acquisition)^[30] Brand continued until acquired by Octopus in 2019^[31]
Future Energy		10,000	Green Star Energy
GB Energy Supply		160,000	Co-op Energy (acquisition)^[32] Brand continued until acquired by Octopus in 2019
Green Star Energy		200,000	Shell Energy (acquisition)^[33] Green Star was a subsidiary of Canada's Just Energy
Iresa		100,000	Octopus Energy^[34]
OneSelect		36,000	Together Energy^[35]
Our Power		31,000	Utilita Energy^[36]
Robin Hood Energy		112,000 domestic, 2,600 business	British Gas^[37]
Solarplicity		60,000	EDF Energy^[38]
Spark Energy		290,000	OVO Energy^[39]
Tonik Energy		130,000	ScottishPower^[40]
Toto Energy		134,000	EDF Energy^[41]
Usio Energy		7,000	First Utility^[42]
Yorkshire Energy		74,000	ScottishPower^[43]

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.^[44] High prices continued into 2022.^[45] 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.^[46]

2021 onwards

Company	Ceased trading	Customers (approx.)	Customers transferred to
Zog Energy ^[47]		11,700	EDF Energy^[48] ^[49]
Simplicity Energy		50,000	British Gas Evolve^[50]
Green Network Energy		360,000	EDF^[51]
Ampoweruk Ltd^[52]	2 November 2021, finalised 3 November	600 or 2,600	Yü Energy ^[53]
Omni Energy ^[54]	3 November 2021	under 10,000	Utilita^[55]
MA Energy	3 November 2021	under 10,000	SmartestEnergy Business Limited
Neon Reef^[56]	16 November 2021	30,000	British Gas^[57]
Social Energy Supply	16 November 2021	5,500	(TBA)
CNG-Power ^[58]	3 November 2021	under 10,000	(TBA)
Zebra Energy	3 November 2021	under 10,000	(TBA)
Bluegreen^[59]	1 November 2021, finalised 3 November	5,600	British Gas
Avro Energy	22 September 2021	580,000	Octopus Energy^[60]
Colorado Energy	13 October 2021	15,000	Shell Energy
Daligas	14 October 2021	9,000	Shell Energy
ENSTROGA	29 September 2021	6,000	E.ON Next^[61]
Green Supplier Limited	22 September 2021	255,000	Shell Energy^[62]
GOTO Energy	18 October 2021	22,000	Shell Energy^[63]
Hub Energy	9 August 2021	6,000 domestic,9,000 others	E.ON Next^[64]
Igloo Energy	29 September 2021	179,000	E.ON Next
MoneyPlus Energy	7 September 2021	9,000	British Gas^[65]
People's Energy	14 September 2021	350,000 domestic,1,000 others	British Gas^[66]
PFP Energy^[67]	7 September 2021	82,000 domestic,5,600 others	British GasPFP was Places for People Energy 2014–2017
Pure Planet	13 October 2021	235,000	Shell Energy^[68]
Symbio Energy	29 September 2021	48,000	E.ON Next
Together Energy	18 January 2022	176,000	British Gas^[69]
Utility Point	14 September 2021	220,000	EDF Energy^[70]
Bulb Energy	23 November 2021	1,700,000	Octopus Energy^[71]
Orbit Energy^[72]	26 November 2021, finalised 29 November^[73]	65,000	Scottish Power^[74]
Entice Energy	26 November 2021	5,400	Scottish Power^[75]

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

Notes and References

1. Web site: 6 October 2008. Energy Supply Probe – Initial Findings Report. live. 1 November 2021. Ofgem. 27–30. https://web.archive.org/web/20081031101424/http://www.ofgem.gov.uk:80/Markets/RetMkts/ensuppro/Documents1/Energy%20Supply%20Probe%20-%20Initial%20Findings%20Report.pdf . 31 October 2008 .
2. Web site: 2020-01-01. Electricity supply market shares by company: Domestic (GB). live. https://web.archive.org/web/20200206225726/https://www.ofgem.gov.uk/data-portal/electricity-supply-market-shares-company-domestic-gb. 2020-02-06. 2020-02-06. Ofgem. en-gb.
3. Web site: 2020-01-01. Gas supply market shares by company: Domestic (GB). live. https://web.archive.org/web/20200206225634/https://www.ofgem.gov.uk/data-portal/gas-supply-market-shares-company-domestic-gb. 2020-02-06. 2020-02-06. Ofgem. en-gb.
4. News: 2019-09-13. New UK energy giant created in SSE-Ovo deal. en-GB. BBC News: Business. 2019-09-16.
5. News: Macalister. Terry. 26 June 2014. Ofgem puts big six energy suppliers under CMA spotlight. The Guardian.
6. Web site: 24 June 2016. Energy market investigation. 8 October 2020. Competition and Markets Authority.
7. Web site: 8 July 2016. The CMA's final report in the energy market investigation. 2020-10-08. Walker Morris.
8. Web site: SSE confirms merger with Npower. BBC News. 2017-11-08. 2018-03-27.
9. News: Vaughan . Adam . SSE and npower scrap merger plan amid 'challenging conditions' . 29 December 2018 . . 17 Dec 2018.
10. News: Vaughan . Adam . Job fears for npower staff, with ownership transferring to E.ON . 29 December 2018 . . 28 Dec 2018.
11. News: Eon closes deal for Innogy shares from RWE . 1 December 2019 . ReNews . 19 September 2019.
12. Web site: Utility Warehouse buys 770,000 customer accounts from npower in £218m deal. www.telegraph.co.uk. 20 November 2013 .
13. Web site: First Utility becomes first independent energy company to reach milestone of 1m customer accounts and pledges 1% of profits to charity. www.first-utility.com.
14. Web site: Opus breaks big six dominance of business energy market. 2015-08-11. Utility Week. en-US. 2019-07-23.
15. Web site: Ofgem refers energy market for CMA competition investigation. 2014-06-26. Utility Week. en-US. 2019-05-05.
16. Web site: Utilita Energy Limited: Annual Report 2017. 31 March 2017. Companies House.
17. Web site: Energy market investigation: Final report. 24 June 2016. Competition & Markets Authority. GOV.UK. 24,388. 5 May 2019.
18. Web site: We support community energy. dead. https://web.archive.org/web/20180612135859/https://www.cooperativeenergy.coop/why-us/we-support-community-energy/. 12 June 2018. Co-operative Energy.
19. Ofgem, All Electricity licensee's, last updated 27 May 2021, accessed 9 June 2021
20. Web site: London Power. 2019-10-29. London City Hall. en-GB. 2020-02-06.
21. Web site: Octopus Energy handed £13.2 million to cover Iresa debts as tenth supplier goes bust. Stoker. Liam. 25 January 2019. Current News. 5 May 2019.
22. Web site: Octopus Energy buys Affect Energy. Bairstow. Jonny. 5 September 2018. Energy Live News. en-US. 5 May 2019.
23. Web site: Ofgem appoints SSE to take on customers of Brilliant Energy. 14 March 2019. Ofgem. 5 May 2019.
24. News: Hailstone. Jamie. 10 August 2020. Bristol City Council sells off part of energy business. Environment Journal. 11 August 2020.
25. News: 8 September 2020. Bristol Energy: Troubled company sells off domestic customer base. BBC News. 9 September 2020.
26. Web site: Ofgem appoints OVO Energy to take on customers of Economy Energy. 11 January 2019. Ofgem. 5 May 2019.
27. Web site: ENGIE UK announces the sale of its residential energy supply business to Octopus Energy. 20 January 2020. ENGIE UK. 22 January 2020.
28. Web site: Ofgem appoints Utilita Energy to take on customers of Eversmart Energy. 10 September 2019. Ofgem. 22 September 2021.
29. Web site: Ofgem appoints ScottishPower to take on customers of Extra Energy. 24 November 2018. Ofgem. 5 May 2019.
30. Web site: Co-op Energy acquires Flow. 2 May 2018. Co-op Energy. 2019-09-06.
31. Web site: Octopus Energy and Co-op Energy confirm major 'strategic energy partnership'. Stoker. Liam. 29 August 2019. Current News. en-gb. 2019-09-06.
32. Web site: Ofgem appoints Co-operative Energy to take on GB Energy Supply's customers. 2016-11-29. Ofgem. en-gb. 2019-10-24.
33. Web site: Shell Energy lands £10.5 million Green Star Energy acquisition deal. Stoker. Liam. 9 October 2019. Current News. en-gb. 2019-10-11.
34. Web site: Octopus Energy to take on 100,000 Iresa customers. Knapman. Helen. 1 August 2018. Moneywise. en. 5 May 2019.
35. Web site: Ofgem appoints Together Energy to take on customers of OneSelect. 13 December 2018. Ofgem. 5 May 2019.
36. Web site: Ofgem appoints Utilita to take on customers of Our Power. 30 January 2019. Ofgem. 5 May 2019.
37. News: 2020-09-04. Nottingham council 'sorry' as Robin Hood Energy collapses. en-GB. BBC News. 2020-10-07.
38. Web site: Solarplicity customers: Your questions on new supplier EDF. 2019-08-16. Ofgem. en-gb. 2019-08-18.
39. Web site: Ofgem appoints OVO Energy to take on customers of Spark Energy Supply Limited. 27 November 2018. Ofgem. 5 May 2019.
40. Web site: 2020-10-09. Ofgem appoints ScottishPower to take on customers of Tonik Energy Ltd. 2020-10-14. Ofgem. en-gb.
41. Web site: Ofgem appoints EDF Energy to take on customers of Toto Energy. 2019-10-26. Ofgem. en-gb. 2020-01-29.
42. Web site: Ofgem appoints First Utility to take on customers of Usio Energy. 18 October 2018. Ofgem. 5 May 2019.
43. Web site: Lempriere. Molly. 7 December 2020. ScottishPower takes on collapsed supplier Yorkshire Energy's customers. 2020-12-08. Current News. en-gb.
44. News: 2021-09-22. Gas crisis: Two energy firms go bust amid warning more to come. en-GB. BBC News. 2021-09-22.
45. Web site: Lempriere. Molly. 2022-01-18. Together Energy becomes first supplier to collapse in 2022 amidst continuing high power prices. live. 2022-01-19. Current. en-gb. https://web.archive.org/web/20220118205445/https://www.current-news.co.uk/news/together-energy-becomes-first-supplier-to-collapse-in-2022-amidst-continuing-high-power-prices . 18 January 2022 .
46. Web site: Ford Rojas. John-Paul. 25 November 2021. Taxpayers left with £1.7bn bill as Bulb, UK's seventh-biggest energy firm, collapses. live. 2021-12-02. Sky News. https://web.archive.org/web/20211124211137/https://news.sky.com/story/collapse-of-britains-seventh-biggest-energy-firm-bulb-confirmed-leaving-taxpayers-to-take-the-strain-12477266 . 24 November 2021 .
47. News: Zog Energy becomes 25th UK supplier to go bust in three months. Jillian. Ambrose. 1 December 2021. The Guardian.
48. Web site: 3 December 2021. Ofgem appoints EDF to take on customers of Zog Energy Ltd. live. 2021-12-10. OFGEM. en. https://web.archive.org/web/20211203155408/https://www.ofgem.gov.uk/publications/ofgem-appoints-edf-take-customers-zog-energy-ltd . 3 December 2021 .
49. Web site: Ofgem appoints EDF to take on customers of Zog Energy Ltd. 3 December 2021. Ofgem.
50. Web site: 2021-01-30. Simplicity Customers: Your questions on new supplier British Gas Evolve. 2021-02-13. Ofgem. en-gb.
51. Web site: 2021-01-30. Green Network Energy Customers: Your questions on new supplier EDF. 2021-02-13. Ofgem. en-gb.
52. Web site: Four more energy suppliers collapse as UK energy crisis deepens. MSN.
53. Web site: What happens if your energy supplier goes bust. 2021-11-11. Ofgem. en.
54. Web site: Four more suppliers collapse as UK energy crisis shows no signs of improving. 2 November 2021. CityAM.
55. Web site: Ofgem appoints new suppliers for customers of CNG Energy and CNG Electricity, MA Energy, Omni Energy, Bluegreen Energy, Zebra Power and Ampower. 2021-11-17. Ofgem. 8 November 2021 . en.
56. Web site: Two more energy suppliers collapse as pipeline delay prompts fresh gas price spike. www.msn.com.
57. Web site: 22 November 2021. Ofgem appoints British Gas to take on customers of Neon Reef Limited and Social Energy Supply Ltd. live. 2021-12-10. OFGEM. en. https://web.archive.org/web/20211122152250/https://www.ofgem.gov.uk/publications/ofgem-appoints-british-gas-take-customers-neon-reef-limited-and-social-energy-supply-ltd . 22 November 2021 .
58. Web site: More energy firms have gone bust in the big squeeze. www.msn.com.
59. Web site: Bluegreen is the latest energy firm to go bust. news.yahoo.com.
60. News: 2021-09-27. Gas price crisis: Good Energy will not take failed firms' customers. en-GB. BBC News. 2021-09-27.
61. Web site: 2021-10-04. Ofgem appoints E.ON Next to take customers of Enstroga, Igloo and Symbio Energy. live. 2021-10-04. Current. en-gb. https://web.archive.org/web/20211004155648/https://www.ofgem.gov.uk/publications/ofgem-appoints-eon-next-take-customers-enstroga-igloo-energy-supply-limited-and-symbio-energy . 4 October 2021 .
62. Web site: Lempriere. Molly. 2021-09-28. Shell Energy takes on failed supplier Green's customers. live. 2021-09-29. Current. https://web.archive.org/web/20210928221629/https://www.current-news.co.uk/news/shell-energy-takes-on-failed-supplier-greens-customers . 28 September 2021 .
63. Web site: 2021-10-21. Ofgem appoints Shell Energy Retail Limited to take on customers of GOTO Energy. live. 2021-10-21. Current. en-gb. https://web.archive.org/web/20211021141935/https://www.ofgem.gov.uk/publications/ofgem-appoints-shell-energy-retail-limited-take-customers-goto-energy . 21 October 2021 .
64. Web site: Lempriere. Molly. 13 August 2021. E.ON Next appointed to take on Hub Energy's 15,000 customers. live. 2021-09-18. Current. en-gb. https://web.archive.org/web/20210813123508/https://www.current-news.co.uk/news/e-on-next-appointed-to-take-on-hub-energys-15-000-customers . 13 August 2021 .
65. Web site: Grundy. Alice. 13 September 2021. British Gas to take on customers of failed suppliers PfP, MoneyPlus. live. 2021-09-18. Current. en-gb. https://web.archive.org/web/20210918185658/https://www.current-news.co.uk/news/british-gas-to-take-on-customers-of-failed-suppliers-pfp-moneyplus . 18 September 2021 .
66. Web site: 20 September 2021. People's Energy customers: Your questions on new supplier British Gas. Ofgem. en.
67. https://www.switch-plan.co.uk/suppliers/pfp/reviews/#:~:text=PFP%20Energy%20stands%20for%20Places%20for%20People%20Energy.,support%20and%20promote%20a%20range%20of%20social%20projects.
68. Web site: 18 October 2021. Ofgem appoints Shell Energy Retail Limited to take on customers of Pure Planet Limited, Daligas Limited and Colorado Energy Limited. ofgem. en.
69. Web site: Lempriere. Molly. 2022-01-25. British Gas takes on Together Energy's 176,600 customers following collapse. 2022-01-27. Current. en-gb.
70. Web site: 17 September 2021. Ofgem appoints EDF to take on customers of Utility Point. live. 2021-09-18. OFGEM. en. https://web.archive.org/web/20210918185659/https://www.ofgem.gov.uk/publications/ofgem-appoints-edf-take-customers-utility-point . 18 September 2021 .
71. Web site: 29 October 2022. UK government approves agreement between Bulb and Octopus Energy, providing certainty to 1.5 million customers .
72. Web site: Orbit and Entice become latest UK energy suppliers to go bust. www.msn.com.
73. Web site: UK energy crisis: More panic as gas giant with 65,000 customers on brink of collapse. www.msn.com.
74. Web site: Appointment of Scottish Power Energy Retail Ltd as Supplier of Last Resort for Orbit Energy Ltd . Ofgem . Ofgem . 4 December 2023 . 18 March 2022.
75. Web site: Appointment of ScottishPower Energy Retail Ltd as Supplier of Last Resort for Entice Energy Supply Ltd and Simply Your Energy Ltd . Ofgem . Ofgem . 4 December 2023 . 18 March 2023.