A Guide to Voltage Optimisation

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Explore the benefits of voltage optimisation in this guide. Learn how it reduces energy consumption, lowers costs, and improves efficiency in your business.

A Guide to Voltage Optimisation

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We live in an era during which it has never been more important to temper our energy use. But while the importance of switching to energy-efficient equipment and using it as efficiently as possible–by, for example, switching off appliances when not in use–there are also other steps that you can take, and one that many people seem unaware of is voltage optimisation. 

What is Voltage Optimisation?

Voltage optimisation is the name given to the systematic, controlled reduction in the voltages received by an energy consumer to reduce energy use, power demand and reactive power demand. While some voltage 'optimisation' devices have a fixed voltage adjustment, others electronically regulate the voltage automatically. 

How Does Voltage Optimisation Work?

Most UK businesses receive an overvoltage from their grid connection, averaging around 242 volts. This is substantially higher than the 220 volts most equipment is designed to work optimally at, causing substantial inefficiencies. 

Voltage optimisation is a transformer-based technology that comes in many forms and works by controlling or optimising the incoming grid voltage to return an energy saving. The principle is based on supplying an optimised voltage level more suitable to the actual electrical device so that it can perform its task more efficiently and in line with the limits of European harmonised voltage. The basic design is a low-loss series connected transformer designed to optimise a whole site or individual loads to target the most optimisable loads.

Pros and Cons of Voltage Optimisation

As with all technologies of this nature, there are potential costs and benefits that you should take into account when deciding whether to proceed with voltage optimisation or not: 


  • Lower monthly bills and lower carbon emissions from streamlined energy consumption.

  • Relatively low return on investment; it can be as low as two years!

  • Voltage optimisation is an extremely mature technology. It has been implemented for over 100 years.

  • It’s flexible and can be installed at the distribution level or the low-voltage incomer.


  • The initial setup costs can be very high. Research should be undertaken to determine whether it is worth it in the long term.

  • You may find your power supply disrupted during set-up or maintenance related to voltage optimisation.

How Does Voltage Optimisation Save Energy?

Generally, power from the National Grid is supplied at a higher voltage than is required. Although the official normal supply voltage in the UK is 230V, the actual voltage supplied by the National Grid fluctuates around an average of 242V. Most appliances are rated at 220V. Therefore, appliances are being supplied with more electricity than necessary to operate, resulting in energy and financial waste and extra wear and tear on your appliances.

How Does Voltage Optimisation Save Money?

Installing a voltage optimiser can reduce the voltage your home or business receives. Voltage optimisers are installed in series with your electricity supply between the distribution transformer and the main low-voltage distribution board. When the electricity passes through your Voltage Optimiser, the supply voltage will be reduced to the required amount. Any excess voltage being supplied will be simply returned back to the grid and not used on-site. Your electrical equipment will benefit from an optimised power supply by simply rejecting and returning the surplus to the grid. 

Applications of Voltage Optimisation

Voltage optimisation can be applied across various uses, from residential to industrial properties. 

Residential Use

These optimisers are designed for domestic environments. They are smaller and less obtrusive, allowing them to be fitted in limited spaces like your utility room.  

Commercial Use

These optimisers are built bigger and with more sophisticated controls. Commercial operations typically have greater demands than a normal household. As such, you can expect commercial voltage optimisers to have advanced controls, such as phase balancing and power factor correction, to meet the demanding needs of a business. 

Industrial Use

The bigger and more complex your business, the more complex your demands may be. Dynamic voltage optimisers are best used in specialised settings that require a sophisticated device that can meet the dynamic and wildly changing demands of a setting. They’re often integrated with smart technology to enable remote monitoring and control over electrical equipment performance. 

Power Problems Solved By Voltage Optimisation

Voltage optimisation can solve several problems relating to power supply, common to businesses. 


These are the waveforms of currents and voltages at multiples of any fundamental frequency of the national grid supply. They come about due to non-linear loads, including variable speed drives and discharge lighting. When the level of harmonics becomes too high, they can damage some pieces of sensitive electrical equipment. Similarly, they can lead to a reduction in the efficiency of HV (high voltage) transformers. Voltage Optimiser units come with a voltage stabiliser, which helps reduce these high levels and prevent any potential damage caused. 


These are brief, very large, and potentially destructive surges in the amount of voltages. They can come from lightning, switching off a large electrical load or switching between power sources. Although they last for a fraction of a second, they can be very destructive to any electrical equipment. They can easily cause data loss, shorten the lifetime of equipment and degradation of electronic components. A voltage optimiser comes with transient protectors that aid in power factor correction.


This refers to inputting a higher voltage than a piece of electrical equipment requires and is even designed to operate at. A national UK power grid outputs an average of 242V, but this can be as high as 252V in some areas. Most pieces of electrical equipment are designed to only use about 220V. This immense and unnecessary voltage can reduce the lifetime of electrical equipment, increase power consumption, and not improve performance.

Power Dips

This refers to a reduction in voltage over a short duration, though in minimal cases, the effects might take a longer period to become apparent. Power dips can cause machinery to stop and contactors and relays to drop out. 

Phase Voltage Ambience

Commercial sites and industries are provided with 3-phase electricity. If there is any imbalance between the phases, overheating might occur, which can lead to energy waste. A voltage regulator can help balance the voltage among these phases, thus saving energy and providing greater energy efficiency while also improving the longevity of your equipment. 

Evaluating the Effectiveness of Voltage Optimisation - Does it Work?

To determine the impact that voltage optimisation could have on a site's energy consumption, a detailed survey should be carried out to understand the dynamics of the load, determine how much of the electrical equipment is voltage-dependent, and determine what proportion of the total energy consumption that represents.

The survey should also include detailed load monitoring for a suitable period of time to ensure all load types and processes are recorded and evaluated, including voltage levels, phase balance, demand levels, and volt drop throughout the site.

If most of a site's electrical consumption is made up of voltage-dependent loads, savings are likely to be high. Savings on voltage-independent loads are likely to be poor, although benefits still exist as operating equipment close to its fundamental design voltage may maintain the life expectancy in line with the manufacturer's expectations.

System features should also be considered based on the return on investment, the dynamics of the load, site conditions regarding voltage fluctuation, and the level of functionality required.

What to Consider When Buying a Voltage Optimiser

So, if voltage optimisers can be very different to each other, what factors should be taken into account when choosing which one to buy yourself? 


The voltage optimiser unit to be installed must have an impeccable efficiency rating of about 97% to 98%. This should be constant during different load conditions and should even work with the lowest input voltage. Whether the voltage optimiser has a low input of 50% or the highest input of 100%, it must be able to operate with full performance. 

In addition, it should not contain any wearable or consumable parts to ensure no maintenance or repair is undertaken thereafter. The lifetime of an effective optimiser should be around 25 years. It should go without saying that the more efficient your optimiser is, the better the returns will be for your business. 

Uninterruptible Functions

Your system should be able to keep manufacturing operating even when there is a breakdown or overload. For this reason, an automatic system that can bypass these issues is preferred. Some come with a voltage stabiliser to counter power surges. After the load or problem is solved, the system comes back on and continues functioning normally. 

Fast Voltage Management

Your system should be able to manage this optimisation independently and quickly. The transformers used for each phase and switching elements, as well as power control gadgets, should all be independent to maintain the system's full performance. The system should have high-speed stabilisation to ensure that machines don’t fail, which could affect production rates.

Cost Considerations

Cost considerations when it comes to voltage optimisation broadly fall into two categories: initial setup costs and long-term savings. Ensure that you consider both when you’re working out your costs and savings. Reducing voltage to the lower end of the statutory voltage range will save money and energy, reducing your electricity costs by a significant margin. The average business energy consumer should recover the initial costs within a few years.

Can Voltage Optimisation Harm My Electrical Appliances?

If anything, the opposite! One of the big advantages of installing voltage optimisation is that it helps to prevent damage to electrical equipment caused by power surges or blowouts. This means that your electrical equipment will last much longer and ensure the optimum lifespan.

Voltage Optimisation vs Power Factor Correction

The choice between a power factor correction (PFC) and a voltage optimisation system depends on the specific needs of your electrical system. In general, PFC is more suitable for applications with a high proportion of inductive loads, such as motors and transformers.

Voltage optimisation is more suitable for applications with a high proportion of resistive loads, such as lighting and heating. In some cases, it may be beneficial to use both systems. This combined approach can provide the most comprehensive energy savings and power quality improvements.

Voltage optimisation can be important in driving down your business costs, but it can get extremely complicated. At Switchpal, we can help! Contact us today, and we can discuss all your options to make your energy bills more affordable while boosting your green credentials. By making the switch today, the savings that you could make could be significant indeed.

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