Discover more about the biggest UK energy suppliers: who they were, and how they’ve changed over recent years. And find out if you should choose a big six supplier over a smaller competitor.
What is the Big Six in energy terms?
The ‘Big Six’ is the traditional term for the UK’s largest energy companies. For decades, 6 companies dominated the market, but Ofgem reformed the market in 2016 to make it easier for new suppliers to gain entry. As a result, many smaller challengers entered to challenge the established Big Six.
For a short period, new suppliers gained enough of a foothold to shake up the energy supplier market. However, after many suppliers went bust in the early 2020s, the number of suppliers has dropped back to 21. That’s the lowest number of energy providers in the UK since 2012. As a result, while some of the names may have changed, Britain’s energy markets are again dominated by just 6 companies. At the end of 2023, more than 87% of British households were supplied by a member of the Big Six, up from 79% in 2020.
Who were the Big Six energy suppliers?
For most of the last 30 years, the energy markets were dominated by 6 companies. They were: British Gas, EDF Energy, E.ON, npower, ScottishPower and SSE.
As the energy market opened up during the 2000s and 2010s, challengers began to acquire more market share.
Who are the Big Six energy suppliers now?
As of March 2024, the Big Six energy utility companies in the UK are:
| Supplier | Electricity | Gas |
| British Gas | 20.4% | 28% |
| Octopus Energy | 17.4% | 17.2% |
| E.ON Next | 16.9% | 14.2% |
| OVO | 13.1% | 11% |
| EDF Energy | 11.1% | 9.2% |
| ScottishPower | 8.7% | 7.5% |
| Combined market share | 87.6% | 87.1% |
Source: Ofgem
(In 2021, npower completed a deal to sell its customer base to E.ON Next, E.ON’s 100% renewable electricity brand. Octopus has grown in recent years through various acquisitions and taking on customers from failed suppliers.)
Which energy supplier is the best?
To determine which is the best energy supplier for you, consider the following:
- Where you live: This may determine which suppliers are available, and what tariffs they offer.
- Tariff cost: This varies according to supplier, tariff and where you live in the UK. Remember, standard variable tariffs may rise and fall in line with changes to the energy price cap. The cap is updated by Ofgem every 3 months.
- Tariff type: If you want a guarantee as to how much your energy could cost over the next 12 months, look for the best fixed-rate deal. Other energy tariffs to consider include prepayment energy tariffs, green tariffs, time-of-use tariffs (Economy 7 and 10) and single-fuel tariffs.
- Payment options: You save money if you pay for your energy up front with Direct Debit. However, this may not be a viable option. If you pay for your energy in advance using a prepayment meter, check what payment types exist to top up your prepay key or card.
- Meter type: Smart meters have a few advantages over standard meters. They allow you to monitor your energy usage to help cut your usage (and bills). Smart prepayment meters can also be topped up online or using an app. This saves you a trip to your local top-up store.
- Contact options: Check to see whether your supplier allows you to get in touch via phone, or whether you must use email or an online portal. Customer reviews: Before signing up, see what the supplier’s existing customers think of the company if customer support is important to you.
Is it a good idea to sign up with a Big Six supplier?
The biggest advantage of taking your energy from a big six supplier is that you’re dealing with a large company. Their size and resources make them far less likely to go out of business than a smaller supplier. However, Ofgem has procedures in place to protect you if your supplier goes bust. Your supply won’t be interrupted, so your lights won’t go out and you won’t freeze. Ofgem also automatically transfers you to another supplier. Once complete, you can look for a better deal and switch without getting any exit fees.
The best thing to do is see what energy deals are available and choose a supplier that meets your needs. This might be a big six supplier, or you might discover a smaller supplier offers a better fit.
What are some alternative choices to the Big Six energy companies?
You can find plenty of alternatives to the Big Six, even after the recent raft of closures. The following is a non-exhaustive list of smaller energy suppliers in the UK in 2024:
- 100Green
- Co-operative Energy*
- E
- Ecotricity
- Good Energy
- Outfox the Market
- Rebel Energy
- Sainsbury’s Energy
- So Energy
- Utility Warehouse
- Utilita Energy
*Co-operative Energy is administered by Octopus Energy but remains a separate company.
Should you switch to a small supplier?
Yes, if you find the right deal. Small doesn’t mean tiny, and it doesn’t mean new either. Some smaller UK energy providers, like Ecotricity, have been established for decades. Most suppliers serve at least 100,000 customers, while both Utility Warehouse and Utilita Energy currently supply electricity (and gas) to around 1.5 million customers between them.
Smaller suppliers also have a reputation for providing better customer service. According to Ofgem, 72% of smaller energy supplier customers were satisfied or very satisfied with the level of customer service in 2023. This compares to 62% for large suppliers.
Could alternative heating fuels be a good idea?
If you’re looking to move away from heating your home with gas, then there are several alternative options to consider. One is to heat your home using oil or LPG. This requires you to install a storage tank, then find a local supplier to top up your oil or LPG when you need to. The costs of installing a system like this, combined with the high price of oil and LPG, mean there may be better alternatives out there.
Most alternatives to heating fuels are powered by your electricity supply. Examples include:
- Electric-powered boiler to heat water and existing heating system (water-fed radiators).
- Electric storage heaters that are heated up overnight using an Economy 7 tariff to save money, then release their heat during the day.
- Heat pumps that extract heat from the air or ground to heat your home and hot water.
If you were to install one of these, you’d need to switch to an electricity-only tariff. Your electricity costs would be higher, but you would hopefully save money on your previous dual-fuel bills.
How do I switch energy suppliers with Confused.com?
You can switch suppliers with Confused.com in just 5 steps. Here’s all you need to know:
- Go to our energy comparison page.
- Enter your details, including postcode and house name or number.
- Confirm your current supplier, tariff and estimated annual consumption.
- We’ll then show you a list of available deals. You can compare these to find the best deal.
- Click ‘Switch today’ next to the tariff you’d like to switch to. We’ll then contact both old and new suppliers to handle the switchover on your behalf. Your switch should take 5-14 days.
Find out more with our energy switching process guide.
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