I've heard of voltage optimsers - what are they?

Voltage optimisers reduce the mains supply to the house from 230V to around 220V. In some situations this can reduce the power used by appliances – saving you money on your electricity bill.

A number of trials have tested different appliances on reduced voltages – with differing results.

Old fashioned light bulbs will use less power at a lower voltage, but they will also be dimmer! A better way of saving energy would be to switch to efficient LEDs. Other simple electrics used for heating - such as kettles and electric hobs - will also use less power, but will also become less hot – meaning you would need to leave the appliance on for longer to generate the same amount of heat.

Other appliances such as TV screens and computers will respond differently to different voltage levels. But most research suggests that there will be minimal (if any) savings.

The biggest savings are likely to be made from appliances with motors – but these can vary greatly depending on the efficiency of the motor and the about of load applied.

Most domestic properties will benefit very little from a voltage optimiser. Bigger savings are likely to be made on commercial buildings.

These are not to be confused with MPPT voltage optimisers used for minimising shading on solar panels!