British Gas has rolled out a tariff offering customers eight hours of free electricity over weekends if they have one of the company's smart meters installed in their home. But while it will cut costs for existing customers, it's still considerably more expensive than the cheapest energy deals available on the market.

The HomeEnergy FreeTime March 2018 tariff lets you opt for free energy between 9am and 5pm on either Saturdays or Sundays – and British Gas will install its own type of smart meter for free so you can qualify. But it's not available for electricity-only customers.

Prices will also be fixed until May 2018, meaning you won't be affected by any price hikes during that time. But founder Martin Lewis has warned customers the new tariff is far from the best energy deal currently available.

He says: "While this is a welcome innovation by British Gas – and certainly will save money for its existing customers who opt for it as it's the same price as its standard tariff, but with eight hours a week free – it's certainly not worth switching to.

"British Gas customers would still be better off ditching and switching. After number-crunching, only a freakish combination of circumstances would make this the cheapest deal on the market.

"This deal gives you free electricity 9am to 5pm on a Saturday or Sunday. That's a third of a day and a day is a seventh of a week. So the free period is less than 5% of the week.

"Yet a typical user on British Gas dual fuel tariff pays £1,044 a year, compared to £734 on the cheapest deal – that makes it over 40% more expensive. Plus as it's dual-fuel only, its only electricity that is free for one daytime - you still pay for gas.

"If your energy use is split evenly between gas and electricity, even a back-of-the-envelope calculation shows the only people who this would be cheapest for those who use more than 80% of their electricity during the free hours. Frankly even if you did all the week's washing, dishwashing and everything else that you could save, you wouldn’t come close to doing this."

You can find the best deals on gas and electricity by using our free Cheap Energy Club to compare prices and see what you can save.

What's the deal?

The main features of the HomeEnergy FreeTime March 2018 tariff include:

  • Free electricity every Saturday OR Sunday (you decide which) from 9am to 5pm until March 2018
  • A British Gas smart meter installed (if required) at no extra charge
  • Fixed until 31 March 2018
  • £20 exit fees per fuel
  • Available for dual fuel only
  • £15 dual fuel discount

The standing charge for each fuel is 26.01 pence per day and the unit rate is 12.77 pence per kWh for electricity and 3.79 pence per kWh for gas (assuming you pay by monthly direct debit).

How does it compare to other energy deals on the market?

The FreeTime tariff standing charge and unit prices appear to be exactly the same as British Gas's Standard Variable tariff, as are those for the other three tariffs it launched this week – HomeEnergy Capped Nov 2017, HomeEnergy Fixed Nov 2018 and Home Energy Reward. But the FreeTime tariff has the free electricity on Saturday or Sunday.

FreeTime (Saturday or Sunday) for typical dual fuel usage, paid by monthly direct debit, works out at £1,022.76 a year, compared with £1,044.10 on the other three HomeEnergy tariffs and the Standard Variable.

Unless you save up all or most of your weekly energy requirements for the free period each week, it's a saving of about £3.60/month on other British Gas tariffs – hardly earth-shattering.

And with small energy firm Iresa offering the same energy for £734 a year, it still sounds expensive compared with the cheapest tariffs on the market.

Interestingly, a typical British Gas Standard Variable customer would actually be £234 a year better off by switching to a deal from Sainsbury's Energy, which is run by none other than British Gas.

Typical annual cost – dual fuel(i)

 Energy use scenario British Gas Standard Variable British Gas FreeTime Iresa (a small energy company)
Even use throughout the week £1,044 £1,023 £734
Using a full day's worth of energy during the free period £1,044 £977 £734
Using a weekend's worth of energy during the free period £1,044 £904 £734
(i) This table is based on Ofgem typical usage figures

Who can get it?

This tariff is only available if you have a British Gas smart meter, or are willing to get one installed – which the firm will do for free.

British Gas customers with pay-as-you-go smart meters can't currently get this deal.

What's a smart meter?

Smart meters are a new type of electricity or gas meter, which send meter readings to your supplier digitally. This puts an end to estimated bills.

The meters also have a display that allows you to monitor your real-time usage.