There are two ways to reduce your electricity bill. As there are many suppliers to choose from, it makes sense to buy your electricity from one of the lower priced suppliers. All electricity suppliers publish their prices on their websites, or you can use one of the price comparison sites.
The second way is to reduce the amount of electricity used. There are several ways to do this. Some of these are free, and some do cost money, however the cost involved is likely to be small compared with the savings.
Economy 7 - is it worth it?
Saving Electricity for no cost
Saving Electricity for £10 or less
Saving Electricity for £50 or less
Saving Electricity - spending over £50
How NOT to save electricity
Lies and myths about electric heating
Economy 7 is a dual-rate supply of electricity. Units used overnight are charged at a significantly lower rate than those used in the daytime. This was normally only provided where storage heaters were installed - the heaters charge up overnight, and release the heat during the day.
However, there is no requirement to have storage heaters, and the dual rate electricity can be used for other purposes. Normally, the whole house switches to the lower rate at night, so anything switched on overnight will use the lower priced electricity.
This was also known as the 'white meter' rate, as in the past it involved a second meter installed next to the first one, and the second meter had a white casing compared to the usual black. Today, multi-rate meters are used.
If it were as simple as night usage being cheaper, everyone would have this. In the real world, it is more complex. The penalty for cheaper electricity overnight is that the units in the daytime are more expensive than normal. Some tariff options also have mid-priced units at certain times of the day, but use is restricted to heating only.
Unless you have many night storage heaters (in other words, your house has them in every room, and there is no other heating), then it is unlikely that Economy 7 will be cheaper. Even an electric immersion heater for your hot water is not likely to use enough electricity overnight to justify the increased daytime costs. Most hot water cylinders have 3kW elements and will heat up from cold in less than an hour - so less than 3 units used if on overnight.
Furthermore, most cylinders do not hold enough hot water for a whole days use, and the heater is likely to be switched on in the daytime as well using the 'boost' function on the controller. With E7, this daytime use will be at the higher than normal daytime rate.
Ideally you need your electricity meter readings for the last year, or several months at least. Find the total number of units used (day+night rate), and then find out what the price per unit would be on your suppliers 'normal' tariff. Multiply the unit price by the total units used, and compare the total to what you actually paid.
If calculating this over less than a year, remember that storage heaters are not normally used in the summer, and usage in general will be higher in the winter.