By Victoria Bischoff Families who pay les to do the vacuuming when it’s raining

. . . or put the washing machine on at weekend How new smart meters are transforming the way we pay for energy

PAYING for power used to be simple. You cooked, did your chores and turned the heating on as needed. Then, every three months, your supplier sent you a bill and you’d pop a cheque in the post.

But it’s about to become a great deal more complicated. Suppliers are launching deals that mean you can buy power in advance, enjoy free electricity at weekends — and even pay a cheaper rate if you wait until it rains to do the vacuuming.

And this is just the start of a major revolution in the way we’re billed for the power and heat we use.

Much of the change is being driven by a new generation of smart meters. These allow suppliers to see exactly when, where and how much energy you use without you needing to submit readings.

That means they can design clever tariffs that fit the needs of different customers.

The Government wants smart meters in every home by 2020. So if you’re not one of the four million who already has one, you will be within three years.

And with bills soaring 80 pc in a decade — and another 15 pc this spring — it’s vital to ensure you’re on the right deal. So what are these new types of tariff — and which offer the best value for money?

FREE POWER AT WEEKENDS

IF YOU usually do all your washing, vacuuming and ironing at the weekend, you could save hundreds with British Gas’s Home Energy Freetime.

To qualify, you must have a smart meter so British Gas can see when you are using electricity.

This is free, and is usually installed by an engineer within a couple of weeks of a request.

It offers customers free electricity between 9am and 5pm on Saturday or Sunday — you pick which day you’d prefer.

Every kilowatt hour (kWh) of electricity used usually costs 13p. So if you consider that the average iron uses 31.2 kWh of electricity annually and a typical washing machine 166 kWh, doing all your laundry on your free day could save you around £25.64 a year. However, even on your free day you still have to pay the so-called standing charge to cover billing, meter and admin costs. This is 26p a day. You will also have to pay for any gas you use as usual, plus electricity used outside of the free period.

Figures from comparison site Energyhelpline show that this tariff will cost the average household using 12,500 kilowatt hours (kWh) of gas and 3,100 kWh of electricity £1,027 a year.

By comparison, the cheapest tariff on the market costs just £834 with a small supplier called Iresa. There is