Big Six Energy Suppliers (UK)
The Big Six Energy Suppliers in Britain are generally taken to be Britain's largest energy suppliers, supplying gas and electricity to over 50 million homes and businesses in Britain, with over 90% share of domestic customers. By "supplier" is meant, the business of buying wholesale power (or gas), paying network and government policy costs and charges, and charging the customers of that supplier, for their electricity (or gas). The assets of a supplier, which is a separate licensed business, are its people, and its offices. The business of four of the big energy Suppliers, including of their wider company groups, does not entail owning, or running, any actual network assets - underground cables, overhead lines, or pipes - to physically deliver electricity or gas. The two exceptions to this, are the two big Scottish Supplier firms, whose wider company groups do own some network assets.
Confusingly, the term "Big Six" has recently been used prominently in the British media to refer, instead, to Britain's energy network firms such as UK Power Networks (which are generally independent of the biggest six British energy suppliers). There has also been a tendency in the media to wrongly refer to electricity network firms as "electricity suppliers", thus sowing further confusion and misunderstanding,
The "Big Six" as the term has most often been used, tends to be a reference to the oldest British electricity companies (which are all also involved in the retail Supply of gas) plus British Gas.
The "Big Six" as the term has most often been used, thus comprises stock market listed Centrica-owned British Gas, EDF Energy, which is owned by the stock-market-listed European energy firm based in France Électricité de France, the two German-owned firms npower and E.ON UK, the Spanish-owned Scottish Power, and the listed Scottish firm SSE.
According to SERIS, the generation businesses of the ‘Big Six’ energy firms amount to around three-quarters of British generating capacity. Three out of the ‘Big Ten’ generators in the UK can probably still be categorised as majority-owned by British shareholders; the other seven are listed firms that are owned by their many shareholders, some of whom will be British, but many of whom may not be British.
New figures from independent research group Cornwall Energy suggest that Britain’s big six energy companies now have a 92.4% share of the market – a decrease from 99.8% in 2009. 
In September 2014, First Utility 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 makes it the seventh-largest energy supplier in the UK and the country’s biggest independent energy provider.
In June 2014, energy watchdog Ofgem referred the energy industry to the Competition and Markets Authority (CMA). The 18 month investigation is to conclude whether the big six have been profiteering and should be broken up.
Since the investigation began, many energy customers have switched to independent energy companies to get better deals and service. According to research from Cornwall Energy, independents have increased their share from 0.2% to 7.6% and 3.8m customers have accounts with smaller, independent suppliers.
|Supplier AAAA||Customers in the UK||Parent||Country of parent||Other divisions and brands||Previous brands|
|British Gas||20 million (business and domestic)||Centrica||UK||Scottish Gas|
|EDF Energy||5.7 million (domestic)||EDF||France||SEEBOARD, SWEB energy & London Electricity|
|E.ON UK||5.3 million||E.ON||Germany||Powergen|
|npower||6.5 million (business and domestic)||RWE||Germany||Innogy, Northern Electric, Yorkshire Electricity|
|Scottish Power||5.2 million||Iberdrola||Spain||PPM Energy||MANWEB|
|SSE||9.6 million||SSE Group||UK||Southern Electric, SSE||Scottish and Southern, SWALEC & Scottish Hydro|
Source of information in this table
- "Energy minister Ed Davey calls in bosses of big six to explain Xmas blackouts | The Sun |News|Politics". The Sun. 2013-12-31. Retrieved 2014-02-08.
- "Ofgem: Power suppliers could be fined over blackouts - ITV News". Itv.com. 2014-01-02. Retrieved 2014-02-08.
- "Ofgem: Questions over suppliers' service in blackout - ITV News". Itv.com. Retrieved 2014-02-08.
- Information in this table taken from UK Power "UK Power". 2012-05-17. Retrieved 2012-05-17.