The UK Energy Retail Market

Who supplies Britain now

Great Britain’s domestic energy market has changed more in the last five years than in the twenty before it. The companies that used to be regional monopolies no longer dominate, one of the challengers became the largest electricity supplier in the country, and roughly three quarters of the suppliers that existed in 2018 no longer do.

These are Ofgem’s own figures, which matter because Ofgem gets them from the industry rather than from a survey. Market shares are of customer accounts, not of energy supplied or money taken, so a large share tells you a company has many customers and nothing whatever about whether it is cheap or good.

The market got smaller, then it got competitive again

For most of the 2000s six companies held almost the entire market. By 2018 there were around seventy active domestic suppliers, and the former incumbents had lost roughly a third of their customers between them. Then in 2021 and 2022 wholesale gas prices rose faster than the price cap allowed retail prices to follow, and about thirty suppliers failed inside eighteen months.

Those customers were not left without power. Ofgem moved each failed supplier’s customers to another under the Supplier of Last Resort process, and the cost of honouring their credit balances was recovered through everyone’s standing charges. What remains is a market with far fewer suppliers than 2018 but a genuinely different top of the table.

Default tariffs, and what these numbers cannot tell you

A default tariff — the one you end up on when a fixed deal ends and you do nothing — is the tariff the price cap actually caps. Ofgem publishes how many accounts sit on one, split by whether the household has been there under or over three years, which is a proxy for how long somebody has gone without shopping around.

Read those figures carefully, because they have two holes. Two of the largest suppliers publish nothing at all, so the table is not a market total. And it excludes prepayment customers entirely — who are among the most likely to be on a default tariff, which biases any share you might calculate downwards. We show what is published and name what is not.

Does switching still save money?

Switching volumes collapsed during the energy crisis for a simple reason: there was nothing to switch to. With wholesale prices above the cap, no supplier wanted new customers, and fixed deals below the cap effectively vanished. The recovery in switching since is a reasonable indicator that competitive offers have returned.

Whether switching saves you money depends on your region, how you pay and how much you use, none of which a national switching figure knows. Our price cap page shows the rates where you live, and the energy bill calculator will put your own consumption against them.