The “Big Six” name is a holdover from the post-2002 UK retail energy market. Three rounds of mergers later (npower into E.ON in 2019, SSE into OVO in 2020, then SSE’s business book transferring to OVO in 2024), it is now effectively the Big Five. This guide breaks down each Big Six / Big Five supplier in 2026 — their parent company, business focus, pricing posture and where they sit in the market.
The original Big Six (history)
The original Big Six emerged from privatisation in the 1990s and consolidated rapidly in the early 2000s:
- British Gas (Centrica). UK’s largest gas supplier.
- EDF Energy. French state-owned (~84%).
- E.ON UK. German-owned.
- npower. German-owned (RWE then Innogy then E.ON).
- ScottishPower. Spanish-owned (Iberdrola).
- SSE. Scottish-headquartered, originally Scottish & Southern Energy.
Big Six today: the Big Five for UK business energy in 2026
British Gas Business (Centrica)
UK’s largest business gas supplier and a top-3 business electricity supplier. Strong nationwide sales force, UK call centres. Particularly active in the SME segment. Owned by FTSE-listed Centrica plc.
EDF Energy
French-owned, large UK generation portfolio (the UK’s largest nuclear fleet plus offshore wind). Active in every business segment from micro to industrial. Very competitive on green tariffs because of the nuclear-backed generation mix.
E.ON Next (E.ON UK + npower legacy)
E.ON UK absorbed npower’s business book in 2019. Operates UK retail under the E.ON Next brand for domestic and SME. Larger I&C customers are served under the E.ON UK Energy Solutions brand. German-owned.
ScottishPower (Iberdrola)
Spanish-owned (Iberdrola). Large UK renewables portfolio — Iberdrola is one of Europe’s biggest wind operators. Particularly competitive in Scotland and the North.
OVO Energy / SSE Energy Solutions
OVO acquired SSE’s domestic book in 2020 and the SSE business book in 2024. Now operates as OVO Energy for domestic and SSE Energy Solutions for business and industrial customers. Owned by Mitsubishi Corporation (~20%) and OVO management/founders.
Where do the Big Six sit on price in 2026?
Generalising across Q1 2026 quote data:
- Most often cheapest among Big Six: EDF Energy (especially for renewables-priority buyers) and ScottishPower (especially in Scotland/North).
- Mid-pack: E.ON Next, OVO/SSE Energy Solutions.
- Most often premium-priced: British Gas Business (premium positioning, strong service).
The Big Six are rarely the absolute cheapest in the market — that title usually goes to mid-market suppliers like Yu Energy, SEFE or Pozitive. But the Big Six are reliably “in range” and offer service depth that smaller suppliers cannot match. See our full UK business energy suppliers guide.
Big Six vs independent suppliers — which should you choose?
Generalising:
- Choose a Big Six if you value brand, service depth, multi-site capability and credit safety. Worth a 1-2p/kWh premium for risk-averse boards.
- Choose a strong independent if you are price-led, run a single site or small portfolio, and are comfortable with smaller-supplier risk.
- Hybrid approach for multi-site portfolios: Big Six for business-critical sites, independents for the rest. Surprisingly common in UK retail and hospitality chains.
Frequently Asked Questions
After consolidation, the modern Big Five (still informally called Big Six) are British Gas Business, EDF Energy, E.ON Next, ScottishPower and OVO/SSE Energy Solutions.
npower’s UK retail business was acquired by E.ON UK in 2019 and folded into the E.ON Next brand. SSE’s domestic book was sold to OVO in 2020; the SSE business book transferred to OVO/SSE Energy Solutions in 2024.
Rarely the absolute cheapest, but reliably “in range”. Mid-market suppliers like Yu Energy, SEFE Energy and Pozitive Energy more often top the cheapest-quote tables.
Independent service rankings vary, but Octopus Energy for Business (not technically Big Six) consistently leads complaint stats. Among the Big Five, EDF Energy and ScottishPower typically out-rank British Gas Business and OVO/SSE on per-customer complaints.
On credit risk, yes — the Big Five all sit on strong investment-grade ratings. Smaller suppliers occasionally fail and get transferred to a Supplier of Last Resort, often at higher rates. For business-critical sites, Big Six counterparty risk is meaningfully lower.
Comparing Big Six vs independent quotes for your meter? Get a free 60-second business energy quote covering all UK suppliers including the Big Five and 30+ independents.
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