The hidden costs of voltage variations


Voltage variation in power systems is the deviation of voltage from its standard level, which impacts power quality. These fluctuations are driven by the distribution of generating infrastructure across the National Grid and changes in demand on the system. During high electricity usage, voltage drops, while low demand and excessive generation leads to voltage elevation.

These variations not only severely damage and reduce the efficiency of equipment but also lead to increased energy consumption and costs too. As a result, this stresses the importance of voltage optimisation technology for localised voltage management.

Integration of renewables

When we discuss the implications of voltage variations, we usually think about electricity generation in the form of traditional centralised power stations. This is where electricity is generated at a few large plants and distributed outward.

However, the increasing use of renewable energy sources is also a factor that influences voltage variations. Unlike traditional centralised power stations, renewables like solar and wind are often distributed across a wide geographic area, which generate and feed power into the grid locally.

Decentralised generation can affect voltage levels locally, often causing overvoltage in certain areas. Usually, this is due to low energy demands and the resulting excess generation from renewable sources.

For example, solar and wind power generation is inherently intermittent because it depends on weather conditions. When there is sufficient sunlight or wind, these sources generate electricity, their output will vary throughout the day in response to these conditions, regardless of the energy demands we place on the system, causing fluctuations in voltage.

Losses are also seen in voltage when electricity travels over long distances. To compensate for this, centralised generation, via traditional power stations, boost the voltage before sending it out to the grid.

With the uptake of decentralised renewable generation feeing into the grid at various geographical locations, losses in voltage over the distribution network can be far less than they have been historically.

Ultimately, this can lead to high voltages, especially during periods of low energy demand and excessive renewable generation. This increases energy consumption and can have a detrimental effect on the lifespan of the equipment.

The impact

Undervoltage and overvoltage in electrical systems have distinct adverse effects on equipment and energy consumption. Excessive undervoltage, below 216V, is often caused by high demand or inadequate power supply and can lead to equipment malfunctions, reduced efficiency, equipment damage and premature failure.

On the flip side, overvoltage typically stems from a combination of boosting voltage levels to compensate for legacy distribution equipment in the grid and excessive decentralised renewable generation during favourable weather conditions and low energy demand. Although CE regulations specify a range of acceptable voltage levels, excessively high voltages beyond the rated range, 253V, are not uncommon.

This can cause electrical devices to consume more energy than they need, generating excess heat, noise and vibration. This heat represents wasted energy, resulting in higher energy bills and increased wear and tear on devices.

Costly CE markings

As mentioned above, CE regulations permit a certain level of voltage variation, but equipment usually receives voltage outside of the specified range. While these regulations indicate compliance with safety standards, it doesn’t guarantee optimal equipment performance under extreme voltages.

For instance, most European countries use 220V-240V under the CE certification, yet most appliances are operating ten per cent above or below that range. Exceeding these limits affects equipment lifespan and efficiency greatly — and that’s before mentioning your wallet.

In fact, according to research from Energy5, equipment failure related to power quality issues can cost businesses up to 17 per cent of their annual maintenance budget.

Through voltage optimisation, businesses can mitigate these risks and even enhance energy efficiency by maintaining voltage within a defined range. For example, if the voltage threatens to drop below the more extreme lower limit of around 216V, the voltage optimiser reverts to supplying standard grid voltage until conditions improve. VO not only saves energy, but also enhances equipment longevity as it ensures optimal levels when grid voltage is too high or low.

If you’re interested in learning how voltage optimisation can help to protect your equipment against voltage variations, please visit