Engie, one of the biggest power companies to rival the 'Big Six' energy giants for years, is launching a new 'roll over' deal which switches existing customers onto its cheapest deal when an offer ends.

The so-called 'roll over promise' for customers was unveiled during the French operator's official launch of its UK home energy business this week, although it first offered deals to domestic households here in October 2016.

Formally GDF Suez, the French company is a major international supplier rivalling some of the UK's big six energy providers in size and is already one of the top suppliers in the UK business energy market.

Amid a flurry of new deals, it also revealed plans for a tracker deal linking what you pay to the wholesale energy market and a cheap fix that locks in the rate until September 2018 (£879/yr on typical use, joint cheapest on the market).

However, what you pay depends on price and where you live. To find your cheapest, you can do a full market comparison using our Cheap Energy Club.

Engie also said that all of its plans will offer 100% renewable electricity, while its Green tariff will guarantee 100% green gas and electricity.

Rollover promise

According to the supplier, it has committed to switch customers over to its cheapest available tariff at the end of their fix.

Though regulator Ofgem rules stops firms from rolling customers onto another fix once their current one ends, Engie has said it will move customers onto a 'price equivalent' of its cheapest available deal, with no exit fees if they want to switch.

This means that when the fix ends with Engie, you'll be moved onto a variable tariff - in line with Ofgem rules - but that tariff price will only cost as much the supplier's current cheapest deal.

Engie Tracker

Engie also gave details of its planned 'Tracker' tariff, which aims to link what you pay with what the supplier pays for gas and electricity on the energy wholesale market.

The tariff - a partly variable deal - will update monthly based on movements in wholesale energy prices. This means what you pay can rise and fall each month.

The tariff isn't currently available - Engie plan to launch it this summer.

"Onus off the customer to switch"

Paul Rawson, Division CEO of Energy Solutions at Engie UK said: "We are bringing a new kind of energy to the UK market, putting the customer at the heart of our business - to help save money, save energy and bring additional benefits to the wider community.

"We believe in fair, clear and transparent pricing, Our Rate Rollover Promise takes the onus away from the customer to switch tariff to get a better deal. We want to deliver sustainable solutions for the UK which is why all of our electricity is renewably sourced as standard."